Vol. 2 Issue 4 6 March - August 2016oec.ac.in/journals/ASAMI_V2_I46.pdf · Applied Science and...

Vol. 2 Issue 4-6 March - August 2016

Applied Science and Advanced Materials International ISSN: 2394-3173 (Print); 2395-3225 (Online)

Editorial Advisory Board

Prof. Madhab Ranjan Panigrahi Orissa Engineering College Bhubaneswar 751 007 Dr Prakash P. Wadgaonkar National Chemical Laboratory Dr Homi Bhabha Road Pune 411 008

Dr. Sabbu Thomas Mahatma Gandhi University Priyadarshini Hills, Kottayam-686560 Kerala, India Dr. Amulya Kumar Panda National Institute of Immunology JNU Complex New Delhi – 110 067

Editorial Board

Dr. Pulickel Ajayan Rice University Houston, Texas,USA Dr. Ganesh Chandra Sahoo Central Glass and Ceramic Research Institute Kolkata Dr. Dipul Kalita CSIR-North Eastern Institute of Science and Technology Jorhat, Assam Dr. Gerhard Eder Institute of Polymer Science 4040 Linz, Austria Dr. Maya Nayak Orissa Engineering College Bhubaneswar

Dr. Balbir Singh Kaith National Institute of Technology Jalandhar Dr. Niva Nayak Orissa Engineering College Bhubaneswar, India Dr. Sridhara Acharya Hydro- & Electro-Metallurgy Department CSIR-Institute of Minerals and Materials Technology Bhubaneswar, India M Behera Silicon Institute of Technology Bhubaneswar, India

Editor-in-Chief

Dr. Subhendu Kumar PaniE.mail: [email protected] Fax: 0091-06758-239723 Phone: 239737; 9776503280

Website: www.oec.ac.in

Published by Dr. Subhendu Kumar Pani on behalf of Hiranya Kumar Centre for Research & Development, Orissa Engineering College,

Bhubaneswar 751 007 Applied Science and Advanced Materials International is issued bimonthly by HKCR&D – OEC and assumes no responsibility for the statements and opinions advanced by the contributors. The editorial staff in the work of examining papers received for publication is assisted, in an honorary capacity, by a large number of distinguished scientists and engineers. Communications regarding contributions for publication in the journal should be addressed to the Editor, Applied Science and Advanced Materials International, Hiranya Kumar Centre for Research and Development, Orissa Engineering College, Bhubaneswar 751 007 Correspondence regarding subscriptions and advertisements should be addressed to the Sales & Distribution Officer, Hiranya Kumar Centre for Research and Development, Orissa Engineering College, Bhubaneswar 751 007 Annual Subscription: Rs 1600.00 $ 300.00* Single Copy: Rs 320.00 $ 60.00* (*Inclusive of first class mail) For inland outstation cheques, please add Rs 50.00 and for foreign cheques, please add $ 10.00. Payments in respect of subscriptions and advertisements may be sent by cheque/bank draft, payable to Hiranya Kumar Centre for Research and Development, Orissa Engineering College, Bhubaneswar 751 007. Bank charges shall be borne by subscriber. Claims for missing numbers of the journal will be allowed only if received within 3 months of the date of issue of the journal plus the time normally required for postal delivery of the journals and the claim. © 2016 Hiranya Kumar Centre for Research and Development, Orissa Engineering College, Bhubaneswar 751 007

http://www.oec.ac.in/

Applied Science and Advanced Materials International ISSN: 2394 – 3173 (Print); 2395 – 3225 (Online)

Vol. 2 Issue 4 – 6 (March - August, 2016)

CONTENTS

Editorial 78

Papers

Poly (methyl methacrylate) Coated Polyurea Microcapsules Containing DEET 81 Sagar S Kulkarni, Siddheshwar B Jagtap, Vishal D Patil & Parshuram G Shukla Comparative Study of Properties between Nanoclay and Soy Pulp Reinforced 85

Thermoplastic Starch Composites

Ajaya Kumar Behera

High Performance Material by e-Beam Irradiation of Nylon6 6 Modified by ABS

Polymer in Presence of Triallylisocyanurate 90

Khushboo Kapoor, Nilay Kanti Pramanik, Ramsankar Haldar

Heat Transfer Enhancement of Three Sides Artificially Roughened Solar Air Heater 96 Arun Kumar Behura, Ashwini Kumar , Ravi Kumar & Souren Mishra

Speaker ID recognition using Quasi-Stationary speech Signal Processing 101

Madhusmita Mohanty, Kaushik Mohanty, M Dash & G Pradhan

Erosion wear behavior of Aluminum-1Magnesium-5Silicon Carbide 106 Composite produced by Modified Stir Casting Method

Birajendu Prasad Samal

The Role of Big Data in Inclusive Growth: An Overview 109 Tapas Ranjan Baitharu & Subhendu Kumar Pani

Performance Analysis of three sided Artificially Roughened Solar Air Heaters 112 Ashwini Kumar, Arun Kumar Behura & Ravi Kumar

The Effect Of Roughness And Flow Parameters For Heat Transfer Enhancement In 117 Artificially Roughened Solar Air Heaters: - A Review

Ravi Kumar, Arun Kumar Behura, Ashwini Kumar & Salila Ranjan Dixit

Design, Synthesis and Fluorescence Study of 2-Phenyl-3-Nitro Chromene Derivatives 124 for H2S Detection

Sabita Nayak Journal Subscription Form 128 Author Index 129 Keyword Index 130

Applied Science and Advanced Materials International ISSN: 2394 – 3173 (Print); 2395 – 3225 (Online)


Microencapsulation of N, N-Diethyl-meta-toluamide (DEET) was carried out by preparing double wall microcapsules of polyurea (PU) and poly (methyl methacrylate) (PMMA). Initially PU microcapsules were prepared by interfacial polymerization technique and subsequently coated with PMMA by solvent evaporation method. Effect of the double wall on morphological and release behaviour of microcapsules was investigated. Surface morphology, size and shape of microcapsules were obtained by an optical microscope and scanning electron microscope (SEM). The release study of DEET from microcapsules was conducted under perfect sink condition and the amount of release was determined by UV-VIS spectroscopy.The paper “Poly (methyl methacrylate) Coated Polyurea Microcapsules Containing DEET” by Sagar S Kulkarni, Siddheshwar B Jagtap, Vishal D Patil & Parshuram G Shukla presents a comparative study for reduction in DEET release.

Nanoclay and soy pulp are two different reinforcement fillers used for developing bio-composites. Different weight percentages of nanoclay and soy pulp were used along with biodegradable thermoplastic starch to develop starch-nanoclay and starch-soy pulp composites respectively. Composites were optimized through mechanical testing. Biodegradation of the composites were studied using soil burial degradation method. The most advantageous value of these composites is the biodegradation property of its constituents, and can be a revolutionary replacement for conventional non biodegradable polymer and polymer based composites. The probable end applications of these composites are in automotive sector, office cuboids, cutlery, packaging, computer cabinets etc. The paper “Comparative Study of Properties between Nanoclay and Soy Pulp Reinforced Thermoplastic Starch Composites” by Ajaya Kumar Behera describes the comparison between Nanoclay and Soy Pulp Reinforced Thermoplastic Starch Composites.

Percent water absorption of all nylon 6,6/ABS blends in presence of tribally lisocyanurate has fallen down significantly with the increasing percentage of ABS and also with the increasing dose of e-beam. The blend of nylon 6,6 with ABS developed a superior material with the novelties of both nylon 6,6 and ABS, while e-beam irradiation of the blend developed cross-linked structures responsible for enhanced physico-mechanical properties of the blend. Morphological studies of the irradiated nylon 6,6/ABS blends were done by Differential Scanning Calorimetry, Scanning Electron Microscopy and Gel Study in order to correlate its reduced water absorption, increased stiffness and improved mechanical strength. The paper “High Performance Material by e-Beam Irradiation of Nylon6 6 Modified by ABS Polymer in Presence of Triallylisocyanurate” by Khushboo Kapoor, Nilay Kanti Pramanik, Ramsankar Haldar analyzes the work relates to the modification of nylon 6,6 by blending with Acrylonitrile Butadiene Styrene (ABS) terpolymer in presence of triallyl isocyanurate (TAIC) followed by irradiating the resulting blend by e-beam.

The rate of heat transfer enhances by providing artificial roughness underside of the absorber plate is considered to be an effective technique and leading to higher collector performance. Under the same operating conditions three sides artificially roughened solar air heaters perform better than those of existing one side artificially roughened solar air heaters. Provision of artificial roughness results in a higher friction factor and consequently a higher pumping power is required. Solar air heater duct with three sides artificially roughened has been analysed by the authors for fully developed turbulent flow and found to perform better both quantitatively and qualitatively as compared to the one side artificially roughened solar air heater under the same operating conditions. Top side (one side) roughened solar air heaters are found to have higher values of heat transfer characteristics from the plate as compared to smooth solar air heaters. Three sides roughened and glass covered solar air heaters have been reported to have even better heat transfer characteristics compared to

Editorial…….

top side roughened ones. Relative roughness pitch, relative roughness height, flow Reynolds number, hydraulic diameter of the solar air heater duct and intensity of solar radiation are the parameters. Air temperature and heat transfer coefficient have been found to increase in the range of 1-9% and 10-40%, over those of one side roughened solar air heaters for the range of parameters investigated whereas, 30-50% and 100-140%, over those of smooth ones. The paper “Heat Transfer Enhancement of Three Sides Artificially Roughened Solar Air Heater “ by Arun Kumar Behura, Ashwini Kumar , Ravi Kumar & Souren Mishra describes the effect of various parameters on temperature and heat transfer characteristics in three sides artificially roughened solar air heaters.

Usually, a few seconds of speech are sufficient to identify a familiar voice. Automatic speaker recognition works on the premise that a person‟s speech exhibits characteristics that are unique to the speaker. The idea to assist the machine, to recognize humans from their voices is quite evident. Speaker recognition is the process of automatically recognizing who is speaking on the basis of individual information included in speech signal. However this task has been challenged by the highly variant of input speech signals. In this e-world, it may be possible to use it for speaker identification and authentic accession in various fields like banking by telephone, telephone shopping, database access services, voice dialing, security control for confidential information areas, and remote access to computers. Another important application of this technology is for forensic purposes, where the voice of the criminal and the voice of the suspect need to be verified as the same from a recorded message. The purpose of this paper is to convert the speech waveform, using digital signal processing tools in matlab, to a set of features (at a considerably lower information rate) for further analysis. When examined over a sufficiently short period of time, its characteristics are fairly stationary. However, over long periods of time the signal characteristic change to reflect the different speech sounds being spoken. Therefore, short-time spectral analysis is the most common way to characterize the speech signal. A wide range of possibilities exist for parametrically representing the speech signal for the speaker recognition task, such as mel frequency cepstral coefficient (MFCC) is the best known and most popular, and will be described in this paper which shows the result of speaker ID matching. The paper “Speaker ID recognition using Quasi-Stationary speech Signal Processing” by Madhusmita Mohanty, Kaushik Mohanty, M Dash & G Pradhan discusses the speaker recognition task. The main purpose of this paper is to select slowly time varying speech sample (it is called quasi stationary) to identify a speaker.

Particle reinforced metal matrix composites (MMCs) are now recognized as important structural materials. Therefore, in the present study a new approach to aluminum metal matrix composites (AMMC) production has been proposed. Aim of the present work was to modify the stir casting method by introducing silicon carbide particles at the bottom of liquid melt (Al) so that its effectiveness would be improved as well as to introduce magnesium chips to the aluminum melt with high recovery of magnesium. The Al-1Mg-5SiC MMC prepared by modified stir casting method was tested for erosion wear in the present work. An erosion apparatus of the „sand blast‟ type is used where particles under desired pressure are impinged onto a stationary target. Erosion wear can be conducted over a wide range of particle sizes, velocities, particles fluxes and incidence angles, in order to generate quantitative data on materials and to study the mechanisms of damage. The test was conducted as per ASTM G76 standards. Statistical methods have commonly been used for analysis, prediction and/or optimization of a number of engineering processes.. The paper “ Erosion wear behavior of Aluminum-1Magnesium-5Silicon Carbide Composite produced by Modified Stir Casting Method “ by Birajendu Prasad Samal addresses to adopt a systematic statistical approach called Taguchi method to optimize the process parameters.

Big data rupture upon the scene in the initial decade of the 21st century, and the first associations to embrace it were online and startup firms. Arguably, firms like Google, eBay, LinkedIn, and Face book were built around big data from the beginning. They didn‟t have to integrate big data with more traditional sources of data and the analytics executed upon them, because they didn‟t have those traditional forms. They didn‟t have to

merge big data technologies with their traditional IT infrastructures because those infrastructures didn‟t exist. Institutions, governments, donors, and NGOs are rapidly talking about „inclusive growth‟. This point is in some ways an attempt to address the deficiencies of prioritizing solely economic growth, and an effort to ensure instead that the benefits of growth are more broadly experienced.The paper” The Role of Big Data in Inclusive Growth: An Overview” by Tapas Ranjan Baitharu & Subhendu Kumar Pani discusses an overview of the inclusive growth introducing the idea that while attempts to tackle inequality and poverty and promote growth can be mutually reinforcing, this link is not automatic.

Provision of artificial roughness on the absorber plate enhances heat transfer rate in solar air heaters, which also results in higher value of friction factor and more pumping power required. Artificially roughened solar air heaters have been analyzed1 and investigated2 for fully developed turbulent flow and have been found to have a better performance, both quantitatively and qualitatively as compared to those of the solar air heaters having smooth solar air heater under the similar operating conditions. A novel solar air heater with three sides artificially roughened has been analyzed3, which result in more increase in heat transfer and friction factor than those of one side artificially roughened solar air heater. Thermal performance of three sides artificially roughened solar air heater has been analyzed4, whereas, one side artificially roughened solar air heater has been optimized5 and investigated6 for the maximum heat transfer, friction factor and the minimum pumping power.. The paper “ Performance Analysis of three sided Artificially Roughened Solar Air Heaters” by Ashwini Kumar, Arun Kumar Behura & Ravi Kumar represents an investigation for the various performance characteristics of three sides artificially roughened solar air heaters with three sides glass covers under actual outdoor conditions and compare well with smooth ones, also having three sides glass covers.

Provision of artificial roughness is made to enhance heat transfer rate in solar air heaters. Information regarding different configurations and geometries of roughness elements producing different quality and quantity of heat transfer is available in literature. This paper reviews the comparative rate of heat transfer quantitatively and qualitatively in artificially roughened solar air heaters of various configurations.. The experimental values of average Nusselt number in the case of multi V-roughness has been found to be the highest. However, the analytical values of average Nusselt number in the end of side roughened solar air heaters are the maximum.The paper “ The Effect Of Roughness And Flow Parameters For Heat Transfer Enhancement In Artificially Roughened Solar Air Heaters: - A Review” by Ravi Kumar, Arun Kumar Behura, Ashwini Kumar & Salila Ranjan Dixit represents Analytical and experimental result as well as worked out values of result with respect to heat transfer data (Average Nusselt number), utilizing the equation/correlations developed by various authors with respect to the roughness and flow parameters (p/e, e/D and Re), for comparison in rate of heat transfer.

The last paper “ Design, Synthesis and Fluorescence Study of 2-Phenyl-3-Nitro Chromene Derivatives for H2S Detection” by Sabita Nayak presents the Fluoregenic properties of different compounds showing good fluorescence in polar solvents. Intracellular reactive sulfur species (RSS) is a general term for sulfur-containing biomolecules. These molecules play critical roles in physiological and pathological processes. Glutathione (GSH), the most abundant intracellular nonprotein thiol, can control intracellular redox activity, intracellular signal transduction, and gene regulation.Fluoregenic α,β unsaturated nitro compounds are used as fluorescent probe for H2S detection in biological system. Here with 2-Phenyl-3-nitro-chromene derivatives were synthesized and its fluoregenic properties were studied with an expectation to use further as new fluorescent probe for H2S. Two nitrochromene named as 7-methoxy-3-nitro-2-phenyl-2H-chromene and 2-(4-methoxyphenyl)-3-nitro-2H-chromen-6-ol were synthesized following Michael aldol reaction of substituted salicylaldehyde and β-nitrostyrene using DABCO in neat condition heating at 40 oC with good yield. Synthesized compounds were well characterised by 1H, 13C NMR and MP study. Both the compounds show good fluorescence in polar solvents.

S K Pani

Editor

ISSN: 2394-3173 (Print)

2395-3225 (Online) Applied Science and Advanced Materials International Vol. 2 (4-6), March - August 2016, pp. 81 - 84

Poly (methyl methacrylate) Coated Polyurea Microcapsules Containing DEET

Sagar S Kulkarni, Siddheshwar B Jagtap, Vishal D Patil & Parshuram G Shukla*

Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road,

Pune-411008, India

Paper Presented in the Second Energy & Materials Science Congress: ENMAT-II

Orissa Engineering College, Bhubaneswar, India, 04-05March, 2016

Abstract Microencapsulation of N, N-Diethyl-meta-toluamide (DEET) was carried out by preparing double wall microcapsules of polyurea (PU) and poly (methyl methacrylate) (PMMA). Initially PU microcapsules were prepared by interfacial polymerization technique and subsequently coated with PMMA by solvent evaporation method. Effect of the double wall on morphological and release behaviour of microcapsules was investigated. Surface morphology, size and shape of microcapsules were obtained by an optical microscope and scanning electron microscope (SEM). The release study of DEET from microcapsules was conducted under perfect sink condition and the amount of release was determined by UV-VIS spectroscopy. Release study shows a reduction in DEET release for double wall microcapsules as compared to neat PU microcapsules.

Keywords Microencapsulation, Double wall, Release study, DEET Microencapsulation has drawn tremendous attention to the research showing to its extensive applications in agrochemicals, pharmaceuticals, electronic ink, coatings, catalysis, dyes, insect repellents, self-healing materials and household products1,2. The sustained/slow release of core materials from microcapsules (MICs) is an essential factor to achieve good efficiency towards desired applications which is mainly affected by leakage and/or fast release of core materials from MICs. To overcome this problem, various attempts such as encapsulation by multi-layered polymeric wall3,4, varying the core loading, nature and composition of monomer(s)5,6 have been reported in the literature. MICs with multi-layered polymeric wall have attracted great interest to the research community due to improvement in thermal stability and strength of wall materials3,4,7-10. The multi layer MICs can also overcome the problem of leakage and/or fast release of core material to some extent. There are numerous reports available in the literature describing double or multiple layered MICs containing various core materials3,4,7-10.

N, N-Diethyl-meta-toluamide(DEET) is an effective synthetic mosquito repellent. However, performance of DEET cannot be maintained for longer period due to volatility and migration rate11,12. Microencapsulation of DEET is effective way to maintain its effect for a longer period. MICs containing DEET with a suitable polymeric wall can hinder the migration and evaporation rate of DEET. Several reports have been published on DEET formulation and encapsulation by various polymeric wall materials with different polymerization techniques13-20. However, all above reports describe the encapsulation of DEET by single polymeric wall material. In our recent article6

we have prepared MICs containing DEET using polyurea and polyurethane as wall materials by in-situ polymerization techniques. The effect of polyurea and polyurethane microcapsule wall on release behaviour of DEET was studied. We observed the slow release of DEET from polyurethane MICs than that from polyurea MICs. In this paper, we have made an attempt to encapsulate DEET by preparing double wall MICs. Firstly MICs prepared with polyurea (PU) wall material by interfacial polymerization technique, are further coated with poly (methyl methacrylate) (PMMA) by solvent evaporation method. Effects of MICs with two polymeric walls on yield, size, morphology and release behaviour of MICs are discussed in this paper.

Corresponding Author: Parshuram G Shukla e-mail: [email protected] Ph: +92 20 2590 2332

82 Appl Sci Adv Mater Int, March - August 2016

Materials and Methods N, N-Diethyl-meta-toluamide (97%) (DEET), toluene 2, 4 diisocyanate (80%) (TDI), poly (methyl methacrylate) (Mw= 3, 50,000), poly (vinyl alcohol), 98% hydrolysed (average Mw = 13,000-23,000) (PVA) and fumed silica (0.007 µm) were purchased from Sigma-Aldrich, USA. Acetic acid glacial (99-100%), ethylene diamine (EDA) and dichloromethane (DCM) were purchased from Merck, India. Distilled water was used as a continuous medium. All chemicals were used as received. Preparation of Polyurea (PU) MICs

Double wall (DWL) MICs containing DEET were prepared by interfacial polymerization technique followed by solvent evaporation. A typical procedure for preparation of DWLMICs containing DEET (50%) is described as follows. 25 mL of 3 wt% of PVA aqueous surfactant solution was taken in a 100 mL glass beaker. To this surfactant solution, a mixture of 1.95 g of DEET and 1.45 g of TDI was added while stirring the mixture at 1000 rpm (revolutions per minute). Then 0.5 g of EDA was diluted in 3mL of distilled water and added dropwise to the reaction mixture over the period of 5 minutes. pH of the reaction mixture was set at 6.5-7.5 by adding few drops of glacial acetic acid. The reaction was continued at room temperature for 3 hours followed by 50oC for 2 hours. Then reaction temperature was brought to room temperature and the stirring speed was reduced to 500 rpm. Then 0.2 g of PMMA was dissolved in 15 g of DCM and added drop wise to the reaction mixture over the period of 20 min. The reaction was continued for further 15 hours. The MICs were isolated by filtration and dried in the oven at 80oC for 4 hours. MICs prepared with 50% of DEET are designated as DWL-MIC (50%) in subsequent discussion. Similarly, using same procedure DWLMICs with 60% and 70% of DEET loading were prepared and are designated as DWL-MIC (60%) and DWL-MIC (70%) respectively in subsequent discussion. MICs were also prepared with 50% and 60% loading without PMMA coating and are designated as PU (50%) and PU (60%), respectively in subsequent discussion. Characterization of MICs

Olympus BX-60, USA optical microscope fitted with Olympus SC30 digital camera was used to measure the emulsion and MICs size. Scanning electron microscope (SEM, Leica 440) was used to study the morphology of MICs. The MICs were sputter coated with the gold before the SEM imaging to avoid the charging. UV-visible

spectrophotometer (Hitachi model 220) was used to study the release of the DEET from PU and DWLMICs. Release Study

A perfect sink condition was followed to carry out release study of DEET from MICs21-23. A sufficient quantity of MICs sample was taken in a 500 mL beaker to which 400 mL of distilled water was added with a steady stirring speed of 200 rpm in a thermostatic bath maintained at 27 ± 0.1 oC. At a particular time interval, 10 mL aliquots were taken out using graduated 10 mL pipette having a cotton plug at the tip to avoid entering of capsules in the aliquot. 10 mL of eluting solvent (water) was added back to make a total volume of 400 mL. The amount of DEET release from MICs was determined by UV spectroscopy at 251 nm (λmax of DEET). The release rate experiments for each sample were carried out in duplicate and average of cumulative release obtained from two sets of experiments was noted. Results and Discussion

Effects of Loading

Table 1 represents yield, size and shape of PU (60%), DWL-MIC (50%), DWL-MIC (60%) and DWL-MIC (70%). All the DWL-MICs show yield around 60-68%. This indicates an increase of DEET loading does not affect the yield of MICs. DEET loading does not show any significant effect on yield and size of MICs.

Table 1 Yield, size and shape of PU (60%), DWL-MIC (50%), DWL-MIC (60%) and DWL-MIC (70%). Experiment Yield

(%) Size

Range (µ)

Shape

PU (60%) 67 2-300 Spherical DWL-MIC (50%) 62 2-300 Spherical DWL-MIC (60%) 60 2-300 Spherical DWL-MIC (70%) 68 2- 300 Spherical

Morphology of MICs

SEM analysis was carried out to study the surface morphology of PU and DWLMICs. SEM photographs of PU (50%) (Prepared for comparison) and DWL-MIC (50%) are shown in Fig. 1. We can see that the PU (50%) shows spherical shaped MICs with a smooth surface [Fig. 1(a-c)]; whereas DWL-MIC (50%) shows spherical shaped MICs with a rough surface [Fig. 1(d-h)]. The rough surface of DWLMICs is due to the formation of PMMA coating over poly urea MICs (Fig. 1f). We can also see that MICs prepared with PU and DWL show no difference in the final size of

83

Kulkarni S S, Jagtap S B, Patil V D & Shukla P G: Poly (methyl methacrylate) Coated Polyurea Microcapsules Containing DEET

MICs. All MICs are found to be in the size range of 2-300 µm and majority of capsules are in the range of 80-150 µm. This observation is in good agreement with the size of MICs observed by an optical microscope (not discussed here). Fig. 1(g) and 1(h) represent SEM photographs of broken MICs. From Fig. 1(g) we can see that the prepared MICs are typical reservoir-type which is in good agreement with our previous results21. The formation of two layers of MICs in which upper layers is PMMA and lower is polyurea can be easily seen from Fig. 1h.

Fig. 1 SEM photographs of PU (50%) ( a, b, c) and

DWL-MIC (50%) (d, e, f, g, h). Release Study of MICs

A systematic release study of DEET from MICs was carried out in water under perfect sink conditions as per literature procedure21-23. Fig. 2 shows percentage (%) release vs. time plots of PU (60%), DWL-MIC (50%), DWL-MIC (60%) and DWL-MIC (70%). All MICs exhibit initial burst (effect) around (17- 25%) within first 5 minutes followed by a sustained release. This burst effect is observed in most of the MICs and is attributed to different factors21,24. We can see that the release of DEET is faster as loading increases (Fig. 2) which can be attributed to the formation of thinner wall at higher loading. Among all MICs, DWL-MIC (50%) shows the slowest release of DEET. After a period of 1440 minutes, DWL-MIC (50%) shows around 45% of DEET release whereas DWL-MIC (60%) and DWL-MIC (70%) show around 55% and 67% of DEET release respectively. For comparison, we have also prepared MICs using only polyurea as wall material (without double wall) with 60% DEET loading. The release of DEET from these MICs was compared with the release of DEET from DWL-MIC (60%). From Fig. 2 we can see that DWL-MIC (60%) shows slow release of DEET

than PU (60% DEET). This indicates PMMA coating on polyurea MICs can effectively decrease the release of DEET.

0 200 400 600 800 1000 1200 1400 1600

20

30

40

50

60

70

DWL-MIC (50%)

DWL-MIC (60%)

DWL-MIC (70%)

PU (60%)

% R

ele

ase

Time (Minute)

Fig. 2 Percentage release vs. time plots of PU (60%), DWL-MIC (50%), DWL-MIC (60%) and DWL-MIC (70%) samples. Table 2 Type of release mechanism n, release rate constant k, time for 40% DEET release and r square values of the PU (60%) and DWL-MICs samples. Experiment n k(min)-n Time

for 40%

DEET release (min)

r2

PU (60%) 0.2052 0.1229 274 0.9834 DWL-MIC (50%) 0.1687 0.1330 1200 0.9799 DWL-MIC (60%) 0.2585 0.0825 754 0.9900 DWL-MIC (70% ) 0.2397 0.1401 91 0.9933

Further release data was analyzed by using following equation and release parameters were obtained21-23.

Mt / M∞ = k t n(1)

Where, Mt and M∞ are amount of active released at time t and at infinite time respectively. M∞ is taken as amount of active loading present in MICs at t = 0. k is release rate constant and n describes the type of release mechanism. For a slab type geometry if n = 0.5 indicates Fickian release (i.e. by diffusion), 1.0 indicates Case II or zero order (by polymer relaxation) and 0.5 < n < 1.0 indicates non-Fickian where diffusion and polymer relaxation both mechanisms are operative. Ritger and Peppas25 have shown that for a hypothetical mixture of 20% 20 µm, 60% 100 µm and 20% 500 µm particles for the Fickian diffusion and Case II transport n value can be 0.30 ± 0.01 and 0.45 ± 0.02, respectively. Considering above stated finding by Ritger and Peppas though the exact release mechanism cannot


be confirmed for population of polydispersed MICs, based on n value approximate release mechanism and/or any change in release mechanism due to change in capsule architecture can be predicted.

Table 2 shows the values of release rate constant (k) and types of release mechanism (n) of all MICs. All MICs show values for n are in the range of 0.1687 to 0.258. It can be seen that release rate constant k values for all capsules are in the range of 0.082 to 0.14 (min)-n. This observation is in good agreement with results obtained in our previous article6. As n values for PU (60%) and DWL-MIC (60%) are close their k value can be considered to assess the release rate. k value for neat PU MICs is 0.1229 which is higher than that of DWL MICs (0.0825). Further, time required to release 40% of DEET from all MICs was also determined from the Fig. 2 and results are summarized in Table 2. For DWL MICs we can see that time required to release 40% of DEET from MICs increases with decreasing DEET loading in MICs. DWL-MIC (50%) shows 40% DEET release in about 1200 minutes whereas DWL-MIC (70%) releases 40% DEET in about 91 minutes. The faster release of DEET in case of DWL-MIC (70%) can be attributed to the formation of thinner wall due to higher loading. We have also compared the time required to release 40% of DEET from PU (60%) and DWL-MIC (60%) samples. From Table 2 it can be seen that PU (60%) releases 40% of DEET around 274 minutes whereas DWL-MIC (60%) takes around 754 minutes to release same amount of DEET from MICs. This indicates PMMA coating on polyurea MICs can effectively decrease release of DEET which supports the results discussed above.

Conclusions

Double wall MICs containing DEET were prepared by interfacial polymerization followed by solvent evaporation method. Polyurea and PMMA were used as wall forming materials in which polyurea wall is prepared by interfacial polymerization techniques and PMMA coat by solvent evaporation method. The morphological analysis obtained by SEM clearly showed the formation of PMMA layer over the polyurea microcapsule wall. DWL MICs show spherical shape with rough surface morphology. No change was seen in the size and yield of MICs after PMMA coatings. Release study showed a reduction in DEET release for DWL MICs as compared to neat PU MICs.

References 1. Arshady R, in Microcapsule Patents and Products,

edited by R Arshady & B Boh (The MML Series, 6), 2003.

2. Shukla P G, in Functional Coatings, Ch 5, edited by S K Ghosh (WILEY-VCH Weinheim, Germany), 2006.

3. Caruso M M, Blaiszik B J, Jin H, Schelkopf S R, Stradley D S, Sottos N R, White S R & Moore J S, ACS Appl Mater Interfaces, 2 (2010) 1195.

4. Tian R, Xiaoli F, Zheng Y, Liang X, Wang Q, Ling Y & Baoshun H, J Mater Chem, 22 (2012) 25437.

5. Liu R, Huang S S, Wan Y H, Ma G H& Su Z G,Colloids Surfaces B: Biointerfaces, 51 (2006) 30.

6. Kulkarni S S, Muthu S M, Jagtap S B, Dandage R G, Jadhav A S & Shukla P G, Appl Sci Adv Mater Int, 2 (2015) 7.

7. Yang Y, Wei Z, Wang C & Tong Z, ACS Appl Mater

Interfaces, 5 (2013) 2495. 8. Chia S M, Wan A C A, Quek C H, Mao H Q, Xu

X, Shen L, Ng M L, Leong K W & Yu H, Biomater, 23 (2002) 849.

9. Li G, Feng Y, Gao P & Li X, Polym Bull, 60(5) (2008) 725.

10. Mookhoek S D, Blaiszik B J, Fischer H R, Sottos N R, White S R & Zwaag S vander, J Mater Chem, 18(44) (2008) 5390.

11. Abiy E, Michael T G, Balkew M & Medhin G, Malaria J, 14 (2015) 187.

12. Patel E K, Gupta A & Oswal R J, Int J

Pharmaceutical Chemical Biol Sci, 2 (2012) 310. 13. Fei B & Xin J H, Am J Trop Med Hyg, 77 (2007) 52. 14. Kasting G B, Bhatt V D & Speaker T J, Toxicol in

Vitro, 2 (2008) 548. 15. Karr J I, Speaker T J & Kasting G B, J Control

Release, 3 (2012) 502. 16. Speaker T J, US Pat 8,685,425 B2, 2014. 17. Salafsky B, He Y X, Li J, Shibuya T & Ramaswamy

A, Am J Trop Med Hyg, 62 (2000) 169. 18. Domb A J, Marlinsky A, Maniar M & Teomim L, J

Am Mosq Cont Assoc, 11(1995) 29. 19. Kitau J, Oxborough R, Matowo J, Mosha F, Magesa

S M &Rowland M, Parasites Vectors, 7 (2014) 446. 20. Baker R W & Ninomiya Y, US Pat 4,808,408 A,

1989. 21. Jagtap S B, Muthu S M & Shukla P G, Polym, 83

(2016) 27. 22. Shukla P G, Rajgopalan N, Bhaskar C & Sivaram S, J

Control Release, 15 (1991) 153. 23. Shukla P G, Rajagopalan N & Sivaram S, J Appl

Polym Sci, 48 (1993) 1209. 24. Ruben M, Racheal A, David Y, Preece J A, Goodwin

T E& Zhang Z, J Microencapsulation, 29 (2012) 463. 25. Ritger P L & Peppas N A, J Control Release, 5

(1987) 37.

http://www.sciencedirect.com/science/article/pii/S0142961201001910








http://www.google.com/search?tbo=p&tbm=pts&hl=en&q=ininventor:%22Tycho+J.+Speaker%22

ISSN: 2394-3173 (Print)

2395-3225 (Online)

Applied Science and Advanced Materials International Vol. 2 (4-6), March - August 2016, pp. 85 - 89

Comparative Study of Properties between Nanoclay and Soy Pulp Reinforced

Thermoplastic Starch Composites

Ajaya Kumar Behera1,2

1Materials Science Centre, Indian Institute of Technology, Kharagpur 721302, India

2Department of Chemistry, Utkal University, Bhubaneswar 751004, India


Orissa Engineering College, Bhubaneswar, India, 04-05 March, 2016 Abstract In this work, nanoclay and soy pulp are two different reinforcement fillers used for developing bio-composites. Different weight percentages of nanoclay and soy pulp were used along with biodegradable thermoplastic starch to develop starch-nanoclay and starch-soy pulp composites respectively. Composites were optimized through mechanical testing. Biodegradation of the composites were studied using soil burial degradation method. The most advantageous value of these composites is the biodegradation property of its constituents, and can be a revolutionary replacement for conventional non biodegradable polymer and polymer based composites. The probable end applications of these composites are in automotive sector, office cuboids, cutlery, packaging, computer cabinets etc. Keywords Nanoclay, Soy pulp, Thermoplastic Starch, Bio-composite, Mechanical Testing

The commercial importance and extreme demand of polymer in micro to macro scale has derived intense applications in the form of composites in various fields viz. automotive, transportation, household, marine, aerospace, infrastructure, military etc. In almost all fields, materials are replaced by polymer and their derived composite due to their light weight, low cost and easy form of application. But most of the commercialized synthetic polymers are not biodegradable in nature. Approximately 4-5% of synthetic polymers are degradable while major synthetic polymers are non-degradable in soil making a great challenge to mankind by triggering soil, water and environment pollution1-3. Synthetic polymers derived from crude petroleum are also being costlier from day to day due to political instability in Organization of the Petroleum Exporting Countries (OPEC).

In order to replace/reduce synthetic polymer based composites, biodegradable polymer like starch, cellulose play important role to fabricate bio-composites. When these materials are plasticized with thermoplastic like polyester, both physical and mechanical properties of composites enhance.

Hence, biodegradable thermoplastic starch (TPS) reinforced nano or bio-composites are the new class of hybrid engineering compounds which provides better mechanical properties, dimensional stability, thermal stability and biodegradability over non-degradable synthetic polymer4,5. Earlier traditional filler reinforced thermoplastic composites like lignin, cellulose, wood flour (WF), rice husk flour (RHF), agro-fibers etc are being utilized as reinforcing material along with thermoplastic / thermoset resin to produce sustainable fiber reinforced as well as particle reinforced composites. These fibers or bio-fillers in composite offer a number of beneficial advantages of low cost, low density, high specific strength and stiffness, eco- friendliness, and biodegradability6,7. Soy pulp, a by product in soy milk industry is rich of protein and carbohydrate. It is composed of soy protein, soy fibers (polysaccharides), and some fats. Polysaccharides include cellulose, arabinan, arabinogalactan, and an acidic polysaccharide complex8. Different active functional groups present in amino acids in soy pulp can interact with that of thermoplastic/thermoset matrix to result in making a strong composite which is not studied well. In this work it was used as reinforcing filler to develop bio-composite.

Nano fillers are the widely used reinforcing material, significantly improve or adjust the different properties of the composite into which they are incorporated, such as mechanical, optical, electrical, thermal or fire-retardant properties. There are two methods by which nanofiller can exhibit

Corresponding Author: Ajaya Kumar Behera e-mail: [email protected]

86 Appl Sci Adv Mater Int, March – August 2016

maximum potentiality viz (i) Surface treatment of nanofillers is essential to increase the filler/matrix adhesion, otherwise there is no change in the properties of the nano-composite (ii) Dispersion of nanofillers is another parameter. It requires considerable energy: vigorous mixing or ultrasonic dispersion. Montmorillonite (MMT) (Na, Ca)0,3(Al, Mg)2Si4O10(OH)2, n(H2O) and the organically modified MMT are the most commonly used natural layered silicates for preparation of nano-biocomposites9,10. Numerous investigations on nanoclay modified thermoplastic have reported that the exfoliation of nanoclay improved the physical and mechanical properties of nano-bio composites than the intercalation morphology11,12. Chiou et al. developed wheat starch-Cloisite nanocomposites and found exfoliation nature of nanoclay reduced water uptake of composites. The extent of intercalation or exfoliation in the starch–nanoclay samples did not affect the temperature at maximum degradation, hence nanoclay has little effect on thermal stability of nanocomposites13. Rhim et al. fabricated poly (lactic acid) (PLA) / nanoclay composite films using the casting method and studied the effect of the type of the nanoclay and its concentration on mechanical properties. They observe composite films without good clay dispersion in the polymeric matrix exhibited lower value of tensile strength and elongation at break than that of pure PLA films14. Melo et al. prepared cassava starch based nanoclay composites using extrusion methods and the starch films demonstrated the better combination of mechanical properties, with high stress and strain at break values. Nanoclays addition at 2.5 wt% was sufficient to decrease water sorption capacity15.

In this work biodegradable polyester blended thermoplastic starch-soy pulp (TPSS) and thermoplastic starch-nanoclay (TPSN) composites were developed and characterized. Soy pulp, a completely biodegradable by product and MMT nanoclay of different weight percentages were utilized separately for fabrication of TPS-bio and TPS-nano composites. Fabricated composites composed of low cost, and biodegradable soy pulp are expected to be a good value added bio-products which can be utilized in packaging and disposable items.

Materials and Methods Thermo plastic starch (TPS) (derived from corn starch and blended with polyester) was supplied by Bio-grade (Nanjing) Pty Ltd., China. Southern Clay Co. USA supplied natural nanoclay montmorillonite (MMT), Glycerol (Merck, India) and soy seeds were procured from local market.

Fabrications of nanoclay reinforced TPS

composites

Blends with various amounts (0, 1, 2, 3, 4, and 5 wt%) of MMT, glycerol (5 wt%) and TPS were prepared by melt mixing at 100 ºC and 60 rpm for 5 min using an internal mixer having double screw extruder (Brabender mixing chamber). These different sets of TPS-nanoclay blends were collected and then compressed in a hot press at the temperature of 105 ºC for 10 min under 6 MPa pressures to prepare TPS-natural nanoclay (TPSN) composites. Fabricated composites comprising 0-5 wt% of MMT are coded as TPSN0-5 respectively.

Fabrications of Soy pulp reinforced TPS

composites

Various amounts (1, 5, 10, 15, 20, and 25 wt%) of soy pulp, glycerol (5 wt%) and TPS were prepared by melt mixing method at 100 ºC with 60 rpm for 5 min using an internal mixer having double screw extruder (Brabender mixing chamber). These different sets of TPS-soy pulp blends were collected and then compressed in a hot press at the temperature of 105 ºC for 10 min under 6 MPa pressures to prepare TPS-soy pulp (TPSS) composites. Fabricated composites comprising 1-25 wt% of soy pulps were coded as TPSS1-6 respectively.

Characterization

Tensile and flexural properties of TPSN and TPSS were characterized according to standard ASTM D638 with cross head speed of 5 mm/min and D790 with cross head speed of 2 mm/min respectively using HOUNSFIELD H10K UTM instrument. From each of the composite eight specimens were tested and average value was reported. From both the sets, highest tensile strength shown composite was considered as mechanically optimized.

X-ray diffraction (XRD) study of optimized TPSN and MMT was performed using a X-ray diffractometer (WAXD, ULTIMA-III, Rigaku, Japan) with nickel filtered Cu-Kα radiation (λ= 0.154nm) operated at 40 kV and 100 mA, at a scanning rate of 1 ˚/min.

Transmission electron microscope (TEM) analysis for bulk morphology study of optimized TPSN composites were characterized using a transmission electron microscope, model JEM-1230, JEOL with an acceleration voltage of 100 kV.

Water absorption and contact angle measurement of optimized TPSN and TPSS were carried out according to ASTM D570 and ASTM D5946 respectively.

Biodegradation analysis of optimized TPSN and TPSS were carried out under soil burial condition in accordance to the method specified in standard BIS

87

Behera A K: Comparative Study of Properties between Nanoclay and Soy Pulp Reinforced Thermoplastic Starch Composites

1623-1992. Field emission scanning electron micrograph (FE-SEM) analysis of optimized composites before and after degradation was taken by using a scanning electron microscope (SUPRA-40, Germany) instrument operated at an accelerating voltage of 5 kV.

Results and Discussion

Mechanical strength analysis

Tensile and flexural strength of TPSN and TPSS composites are given in Table 1. With increase in natural nanoclay content from 0 to 5 wt%, tensile strength and tensile modulus of TPSN composites increased due to reinforcement of nano filler. TPSN3 showed tensile strength and tensile modulus

of 2.94 MPa and 76.8 MPa as compared to that of 1.57 MPa and 56.2 MPa of virgin TPS respectively. Similar trend in result obtained for flexural strength of TPSN composites. Elongation at break value of TPSN composites decreased with increase in nanoclay amount due to improvement in brittleness property. The tensile strength and modulus of TPSS composites increased with the increase in filler loading from 1 to 10 wt%. There is 112% increment in tensile strength and 98% in flexural strength of the composite containing 10 wt% soy pulp16. This increment in tensile properties of TPSS3 composite is due to the better interfacial bonding between soy pulp and the starch. Interfacial bonding obtained might be due to possible formation of chemical bonding between the hydroxyl group of filler and that of the matrix.

The composites exhibited brittle properties when the amount of soy pulp exceeds 10 wt% resulting in catastrophic decrease of the tensile strength and modulus values of composites. In case of TPSS1, the EB value is highest and monotonically decreased with increment in filler content explaining increasing brittleness among composites.

Both TPSS3 and TPSN3 were considered as optimum among their respective composite batches.

XRD and TEM analysis of optimized TPSN

composite

XRD graphs of natural nanoclay (MMT), and TPSN3 is shown in Fig. 1(a). MMT showed its characteristics peak at around 7.17° (2θ) which corresponds to interlayer clay spacing (d spacing) of 7.6 Å17. In its concerned composite i.e., TPSN3, no peak obtained suggested exfoliation nature of nanoclay at the interphase. TEM photographs of TPSN0 and TPSN3 and selected area electron diffraction (SAED) micrographs of TPSN3 are given in Fig. 1. In TPSN0, smooth surface of thermoplastic starch is shown while in TPSN3

individual clay layers are separated from each other (marked by arrow) showing exfoliation nature of nanoclay in TPS. Exfoliation of nanoclay helped to improve the physical and mechanical properties of TPS-nanoclay composite as explained above18.

Fig. 1(a) XRD graphs of MMT, TPSN3 composites; TEM micrographs of (b) TPSN0, (c) TPSN3, and (d) SAED photographs of TPSN3

Table 1 Tensile and Flexural properties of TPSN and TPSS composites Composite Tensile strength Tensile modulus Elongation at break Flexural strength Flexural modulus

(MPa) (MPa) (%) (MPa) (MPa) TPSN0 1.57 ± 0.09 56.2 ± 4.31 6.54 ± 0.22 1.72 ± 0.12 52.4 ± 4.31 TPSN1 2.43 ± 0.13 64.4 ± 4.54 6.26 ± 0.18 2.59 ± 0.11 62.2 ± 4.54 TPSN2 2.67 ± 0.12 71.3 ± 4.60 6.08 ± 0.24 2.87 ± 0.10 72.3 ± 4.20 TPSN3 2.94 ± 0.12 76.8 ± 4.24 5.86 ± 0.18 3.14 ± 0.14 74.5 ± 4.25 TPSN4 2.29 ± 0.11 65.7 ± 4.38 5.58 ± 0.26 2.78 ± 0.11 62.7 ± 4.48 TPSN5 1.91 ± 0.10 58.8 ± 4.32 5.42 ± 0.16 2.51 ± 0.12 56.8 ± 4.12 TPSS1 3.31 ± 0.04 53.5 ± 4.31 8.78 ± 0.18 3.24 ± 0.03 54.2 ± 4.36 TPSS2 4.26 ± 0.03 67.9 ± 4.52 7.24 ± 0.22 4.02 ± 0.03 66.8 ± 4.43 TPSS3 7.02 ± 0.04 82.7 ± 4.78 6.82 ± 0.25 6.41 ± 0.04 76.5 ± 4.61 TPSS4 4.92 ± 0.04 60.2 ± 4.30 5.89 ± 0.24 3.79 ± 0.04 58.2 ± 4.37 TPSS5 3.68 ± 0.05 49.7 ± 4.51 5.32 ± 0.22 2.58 ± 0.03 46.9 ± 4.33 TPSS6 2.04 ± 0.06 44.8 ± 4.60 4.98 ± 0.12 1.86 ± 0.05 42.7 ± 4.28

88 Appl Sci Adv Mater Int, March – August 2016

Contact angle and Water absorption study of

optimized TPSN and TPSS

Water sensitivity is an important criterion for many practical eco-friendly applications of TPS-soy pulp and TPS-nanoclay products. Contact angle and water absorption values after 24 h immersion in water of mechanically optimized composite with respect to TPSN0 are given in Table 2. It was found TPSS composites have lowest contact angle value indicating highest water uptake property among the samples. More the contact angle value of the composite more will be the hydrophobic nature. Water absorption of TPSN0, TPSN3, TPSS3 are 5.8%, 15.8%, and 22.7% respectively after immersing in distilled water at RT for 24. Due to the presence of polyester, the water sorption by TPSN0 was found only 5.8%, while presence of nanoclay hindered the path of water penetration, resulting only 15.8% of water sorption. But due to

the presence of soy pulp (which is hydrophilic in nature) the TPSS6 composite absorbed maximum i.e. 30.6%. Water absorption and thickness swelling of composites revealed that both TPS-nano and TPS-bio composites are water stable in nature19. Soil-burial degradation analysis of optimized

TPSC and TPSM

Weight loss after different periods in soil burial of TPSN and TPSS are reported in Table 2. It was found TPSN0 without any nanoclay is lost less weight as compared to TPSN3 and TPSS3. After 60 days under soil burial TPSN0, TPSN3, and TPSS3 lost 30.2%, 41.4% and 48.6% in weight respectively. Weight loss of TPSS exhibited the highest weight loss after 60 days of biodegradation as compared to that of the other samples. It has lost 54.9% of its original weight (TPSS6), while TPSN1 lost only 43.5%. That might be due to hydrophilic soy pulp (25 wt%) facilitated the entrance of water in composite and helped micro-organisms for degradation. Generally, the reinforcement of higher percentage of soy pulp to TPS enhanced the

degradation rate of starch-soy composite, while small percentage loading of nanoclay lost less weight due to the presence of nanoclay which prevents microbe attack20.

FE-SEM analysis of biodegraded sample

Field-emission SEM photographs of biodegraded samples are given in Fig. 2. TPSN0 [Fig. 2(a)] and TPSS3 [Fig. 2(c)] shows smooth surface before biodegradation. After 60 days of degradation it was found degraded TPSS3 [Fig. 2(f)] and degraded TPSN3 [Fig. 2(e)] has many cavities on its surface (marked by circle and arrow). Both composite surfaces were found roughened, degraded, and in maximum places matrix has been uprooted by microbes. This explains the TPSN0 composite degraded less [Fig. 2(d)] while TPSS3 composite surface degraded maximum due to presence of soy pulp.

Fig. 2 SEM micrographs of (a) thermoplastic starch (TPSN0), (b) TPSN3 (c) TPSS3, and after 60 days of biodegradation (d) TPSN0, (e) TPSN3, and (f) TPSS3.

As soy pulp filler is highly moisture sensitive in nature it produced strong starch-soy pulp composite [Fig. 2(c)] but due to presence of protein and carbohydrate easily attacked by microbes resulting

Table 2 Water sensitivity and weight loss (after 60days) of TPSN and TPSS composites Composite Contact angle Water absorption Thickness swelling Weight loss

(°) (%) (%) (%) TPSN0 97 ± 0.5 5.8 ± 0.2 6.2 ± 0.2 30.2 ± 0.5 TPSN1 94 ± 0.5 7.2 ± 0.2 10.8 ± 0.2 43.5 ± 0.6 TPSN2 92 ± 0.5 10.5 ± 0.2 12.5 ± 0.2 42.7 ± 0.5 TPSN3 90 ± 0.5 15.8 ± 0.2 16.8 ± 0.2 41.4 ± 0.6 TPSN4 88 ± 0.5 18.1 ± 0.2 19.6 ± 0.2 38.8 ± 0.5 TPSN5 85 ± 0.5 22.3 ± 0.2 26.3 ± 0.2 37.1 ± 0.5 TPSS1 88 ± 0.5 18.8 ± 0.2 20.2 ± 0.2 42.2 ± 0.5 TPSS2 85 ± 0.5 20.9 ± 0.2 22.4 ± 0.2 45.6 ± 0.6 TPSS3 84 ± 0.5 22.7 ± 0.2 24.7 ± 0.2 48.6 ± 0.5 TPSS4 82 ± 0.5 25.2 ± 0.2 26.2 ± 0.2 50.2 ± 0.6 TPSS5 79 ± 0.5 27.7 ± 0.2 28.6 ± 0.2 52.1 ± 0.5 TPSS6 76 ± 0.5 30.6 ± 0.2 32.4 ± 0.2 54.9 ± 0.5

89

almost lost of smooth surface after 60 days of degradation20.

Conclusions The objective of this work was to develop and characterize biodegradable TPS- nanoclay and TPS-soy pulp composites. It was found with reinforcement of natural nanoclay tensile strength of composites increased up to 88%. Similarly 10wt% soy pulp loaded composite (TPSS3) showed maximum tensile strength of 7.02 MPa which is nearly 350% enhancement. Both XRD and TEM analysis of optimized TPS-nanoclay composites proved formation of exfoliation structure in concerned composite. Contact angle and water absorption values of composites indicated slow decrease in hydrophobic nature among TPSN composites while rapid change in such properties in case of TPSS composite obtained due to presence hydrophilic soy pulp. Weight loss and FE-SEM photographs of degraded sample proved developed composites are biodegradable in nature. Hence these composites are eco-friendly unlike synthetic plastic and can be utilized in different sectors like packaging, decorating and automobile, etc. References 1. Behera A K, Adhikari B & Kar P, Polym Sci Ser B,

57(2015) 159. 2. Paiva L B, Morales A R & Guimaraes T R, Mat Sci

Eng: A, 447 (2007)261.

3. Magniez K, Voda A, Kafi A, Fichini A, Guo Q & Fox B, Appl Mater Int, 5 (2013) 276.

4. Zhang Y, Liu Q, Hrymak A & Han J H, J Polym

Environ, 21 (2013) 122. 5. Zhang J & Sun X, Biomacromol, 5 (2004) 1446. 6. Zhang J & Sun X, Macromol Biosci, 4 (2004) 1053. 7. Yang H S, Kim H J, Son J, Park H J, Lee B J &

Hwang T S, Compos Struct, 63 (2004) 305. 8. Carvalho A F, Curvelo A S & Agnelli J M,

Carbohydr Polym, 45 (2001) 189. 9. Behera A K, Avancha S, Manna S, Sen R & Adhikari

B, Polym Eng Sci, 54 (2014) 345. 10. Behera A K, Avancha S, Sen R & Adhikari B, Polym

Plast Technol Eng, 52 (2013) 833. 11. Huang X & Netravali A, Compos Sci Technol, 67

(2007) 2005. 12. Nanda P K, Rao K K & Nayak P L (2007) Polym

Plast Technol Eng, 46 (2007) 207. 13. Chiou B, Wood D, Yee E, Imam S, Glenn G M &

Orts W J, Polym Eng Sci, 47 (2007) 1898. 14. Rhim J W, Song S, Ha C S, LWT- Food Sci Technol,

42 (2009) 612. 15. Melo C, Garcia P S, Grossmann M V, Yamashita F,

Antonia L H & Mali S, Braz Arch Bio Technol, 54 (2011) 1223.

16. Behera A K, Avancha S, Sen R & Adhikari B,J Appl

Polym Sci, 127 (2013) 4681. 17. Behera A K, Appl Sci Adv Mat Int, 1 (2015) 160. 18. Behera A K & Adhikari B, Appl Sci Adv Mat Int, 2

(2015) 11. 19. Avancha S, Behera A K, Sen R & Adhikari B, J Reinf

Plast Comp, 32 (2013) 1380. 20. Behera A K, Avancha S, Basak R K, Sen R &

Adhikari B, Carbohydr Polym, 88 (2012) 329.

Behera A K: Comparative Study of Properties between Nanoclay and Soy Pulp Reinforced Thermoplastic Starch Composites

http://www.ncbi.nlm.nih.gov/pubmed/15244463

Applied Science and Advanced Materials International Vol. 2 (4-6), March – August 2016, pp. 90 - 95

High Performance Material by e-Beam Irradiation of Nylon 6,6 Modified by

ABS Polymer in Presence of Triallylisocyanurate.

Khushboo Kapoor, Nilay Kanti Pramanik, Ramsankar Haldar*

Material Science Division, Shriram Institute for Industrial Research,19 University Road,

Delhi- 110 007, India


Orissa Engineering College, Bhubaneswar, India, 04-05 March, 2016

Abstract The present work relates to the modification of nylon 6,6 by blending with Acrylonitrile Butadiene Styrene (ABS) terpolymer in presence of triallyl isocyanurate (TAIC) followed by irradiating the resulting blend by e-beam. Percent water absorption of all nylon 6,6/ABS blends in presence of triallyl isocyanurate has fallen down significantly with the increasing percentage of ABS and also with the increasing dose of e-beam. The blend of nylon 6,6 with ABS developed a superior material with the novelties of both nylon 6,6 and ABS, while e-beam irradiation of the blend developed cross-linked structures responsible for enhanced physico-mechanical properties of the blend. Morphological studies of the irradiated nylon 6,6/ABS blends were done by Differential Scanning Calorimetry, Scanning Electron Microscopy and Gel Study in order to correlate its reduced water absorption, increased stiffness and improved mechanical strength. Keywords ABS, Cross linking, e-beam irradiation, nylon 6,6, TAIC, Water absorption

Nylon 6,6 being a versatile engineering polymer is widely used in various engineering applications. But due to its hygroscopic nature nylon 6,6 is not very successful material in outdoor engineering applications, especially in the places where humidity, high temperature and repeated impact are encountered1. Due to hygroscopic nature it absorbs moisture from atmosphere which affects badly on a range of properties of nylon 6,6 resulting in poor processibility, dimensional unstability, weaker mechanical and chemical properties and finally on the performance of products made out of it2. Because of its sharp melting and rapid crystallization properties processing of nylon 6,6 are also difficult. Apart from these drawbacks nylon 6,6 possesses some superior physico-mechanical properties and could be a potential applicant in critical engineering field if the above shortcomings are overcome.

Several efforts have been put forth to minimize the drawbacks of nylon 6,6. The most convenient

way is to introduce crosslink structure into the way is to introduce crosslink structure into the polymer. Cross linking among the polymer chain can be brought either by chemical means or by using high energy ionizing radiation like gamma rays or electron beam. Radiation based processing for cross linking of polymer is an established technology and has many advantages over the conventional chemical methods3,4. First of all, it is energy efficient as it consumes less energy compare to thermal or chemical means to bring the same degree of modification. Secondly, better handling of materials as the modification can be brought out in the solid state and it can be applied directly to finished product. Thirdly, the radiation induced cross linked product remained contamination free as there is no use of initiator, catalyst or other chemicals to initiate the cross linking reaction. Lastly, it is very much reliable, environmental friendly and controllable.

The possibility of cross linking on nylon 6,6 have been studied by number of researchers starting from Charles by, who for the first time successfully cross linked nylon 6,6 with high energy radiation coming from an atomic piles5. Latter, Lawton et al, Zimmerman and Deeley on irradiation of Nylon 6,6 using high-energy pile radiation showed that the primary effect was cross-linking accompanied by considerable degradation and loss of crystallinity6-8.

Corresponding Author: Ramsankar Haldar e-mail: [email protected] Ph: 9810810037

ISSN: 2394-3173 (Print)

2395-3225 (Online)

mailto:[email protected]

91

Radiation cross linking of nylons also reported recently by several researchers9-11 but most of the cases they used extruded films, yarns or fibers. Only a few works report the effect of e-beam radiation on injection molded specimens12,13.

Another approach to overcome the limitations of nylon 6,6 and widening its application areas is the modification by blending ABS with it through appropriate compatibilization. Interest in blends of nylon 6,6 with ABS generates from the possibility of synergistic combination of the desirable characteristics of both of these materials. Blends of nylon 6,6 with ABS are expected to have significant commercial interest, as nylon 6,6 provides its good strength, stiffness and resistance to non-polar solvents to the resulting blend, while ABS contributes toughness and good electrical properties. The properties of the resulting blends can be further greatly improved through cross linking of the nylon 6,6 component, when the products derived from the blends are irradiated suitably by electron beam. In this communication we have reported the detailed investigation of the effect of e-beam irradiation on nylon 6,6/ ABS blends in presence of TAIC as crosslinker towards the improvement of physico-mechanical properties.

Materials and Methods

Injection molding grade nylon 6,6 granules, Zytel 101L, from DuPont, USA was used in this study.ABS used in this study was Absolac 380 procured from INEOS ABS India Ltd. Vadodra, Gujrat. LR grade Triallylisocyanurate (TAIC) from Acros Organics, Belgium, was used as cross linker. The LR grade formic acid (85%) used as solvent in this study obtained from SD Fine- Chem limited, India. Specimen preparation

Extrusion- melt blending of nylon 6,6 with varying percentages of ABS was done. Nylon 6,6 granules were extruded with ABS at different percentages (10 % to 50 %, with an interval of 10%). Molds for test specimens to be operated in the microprocessor based injection moulding machine, Ferromatic Milacron have been fabricated. The different blend compositions were mixed with (2%) triallylisocyanurate (TAIC) as cross linker and injection molded into the test specimens. The test specimens were treated with e-beam irradiation at varying doses.

E- beam irradiation of the molded specimens

Nylon 6,6 specimens of different composition were irradiated by e- beam at Bhabha Atomic Research Center, India using 2 MeV E-Beam Accelerators in

air at ambient temperature (303 K). The specimens were arranged in array on stainless steel trays and attached to the conveyor system which carried the trays at a speed of 3 cm/s and was received 10 kGy e-beam dose per pass. The penetrability of the electrons in the nylon 6,6 molded specimens was ensured by the optimization of the beam energy. For all the test specimens, single-side irradiation was enough for complete penetration. The values of radiation doses were 50,100,150, 200, 250 and 300 kGy. As soon as the irradiation was over, the specimens were repacked in zipper polyethylene bags to minimize the moisture absorption.

Characterization

The specimens irradiated at various dose levels from 0 kGy to 300 kGy with an interval of 50 kGy were evaluated for various physico-mechanical properties as described below: Tensile Properties

Tensile strength, tensile modulus and elongation at break were determined according to ASTM D 638-94b using 10 mm dumbbell on a Tinius Olsen Universal Testing Machine, keeping the grip distance 100 mm and speed 50 mm/ min.

Flexural properties

Flexural strength and flexural modulus were determined as per ASTM D790-92 on the same Universal Testing Machine at cross head speed 1.33 mm/min and support span distance 48 mm. Izod impact strength

Izod impact strength was measured at room temperature on notched specimens according to ASTM D256-93a on the Ceast Universal Pendulum 6545 in the Izod mode.

Rockwell hardness “R”

Rockwell ‘R’ hardness was determined as per ASTM D785-93 by Rockwell hardness tester, Model TSM-DM 2011/40 of Saroj Pvt Ltd, India.

Percent water absorption

Water absorption was determined following ASTM D570-81 on unnotched izod impact samples at 23 ± 2 0C using a Mettler balance, Model AG 204 with four decimal accuracy. Final weight – Initial Weight

Water absorption = x100

Initial weight The values obtained are the average of three reading.

Gel content

Percent gel was determined by using about 0.5 g sample collected from the specimens and dipped in 85% formic acid. After extraction at room

Kapoor K, Pramanik N K & Haldar R: High Performance Material by e-Beam Irradiation of Nylon 6,6 Modified by ABS Polymer in Presence of Triallylisocyanurate.

92

temperature for three days the insoluble gels were collected by filtering through a fritted glass crucible and weighed followed by determining their percentages in the respective samples. Three samples were extracted to determine gel/sol content and the average was reported. Weight of unextractable material

Gel Content = x 100

Initial weight of sample

Radiation chemical yield of cross linking and chain scission were calculated by using Charlesby-Pinner equation14: S + S1/2 = (p0 / q0) + 1/(q0 UD)

Where S is the sol fraction, p0 and q0 are the chain scission and cross linking density per unit dose (kGy–1) respectively, U is the number-average degree of polymerization of the polymer before irradiation, and D is the dose (kGy) of radiation.

The values of p0 and q0 were obtained graphically from the experimental curve of S + S1/2 versus 1/D. The number of polymer chain scission per 100 ev energy absorbed G(S) and the number of polymer crosslink site per 100 ev energy absorbed G(X) are related to p0 and q0 by the relation9,13: G(S) / G(X) = 2 (p0 /q0) Differential scanning calorimetry (DSC)

DSC was carried out on the samples under nitrogen atmosphere with a differential scanning calorimeter, model Q200, of TA instruments, USA. About 8 mg of samples were weighed in aluminum DSC pan for these experiments. The samples were heated from room temperature to 300°C at a heating rate of 10°C/min, kept at 300°C for five minute and then cooled down to room temperature at a cooling rate of 10°C/min. Percent crystallinity was calculated using the following equation: Crystallinity (%) = (∆H Exp X 100 ) / ∆HF

Where H Exp = Heat of fusion of the sample under study; HF= Heat of fusion of the 100% crystalline nylon 66

Heat of fusion of the 100% crystalline nylon 6,6 was taken as 196 J / g in the calculation of percent crystallinity15.

Scanning electron microscopy (SEM)

The Scanning Electron Microscope used in this study was EVO-18, ZEISS make from Amity University, India. The sample was cut into smaller pieces having diameter ½ inches approx and mounted on a circular metallic sample holder. The conductive coating or spattering of Gold and Palladium was done in the ratio of 90:10 for about 15 mins respectively. The sample was then placed inside the SEM chamber followed by morphological analysis. Different images were recorded at varying

magnifications: 1000KX, 5000 KX, 10,000 KX, 20,000 KX, 50,000 KX.

All the test specimens before testing were sealed in dry polyethylene pouches and stored in a fresh silica gel filled desiccators as soon as they were released either from the mold after injection molding or from the accelerator after irradiation by e-beam. Ten specimens were tested for tensile properties and impact strength, five specimens for flexural properties and hardness, and three specimens for water absorption, while the average of all the values was reported as the result. We have considered the minimum thickness of a test specimen in the calculation of mechanical strengths and this is because the weakest point in a specimen lies in its thinnest section. Standard deviation was determined over the entire range of data and in every case the error was calculated to less than1% of the value reported.

Results and discussion Tensile properties were studied on different compositions of nylon 6,6/ ABS blends, injection molded and irradiated by electron beam at various doses. The results obtained for tensile strength for different materials have been shown in Fig. 1. It may be noted that the tensile strength of virgin nylon 66 has fallen gradually with increasing ABS concentration as well as increasing radiation dose. On the other hand, at 200 kGy e-beam and with 5% ABS concentration there is 10% increase in tensile strength as compared with virgin Nylon 6,6. Mode of deformation in tensile testing of virgin nylon 6,6 was of yielding type indicative of ductile failure at lower doses of e-beam and the extent of yielding decreased with the increasing dose of e-beam showing brittle failure. However, when cross linkers were added into the formulation, the deformation of nylon 6,6 remained ductile through-out the entire range of dose applied.

Fig. 1 Variation of tensile strength of various nylon 6,6/ ABS blends with ABS concentration at different doses of e- beam

Flexural modulus increased at lower ABS concentration till 10%, after which there was a

Appl Sci Adv Mater Int, March - August 2016

93

decrease to a constant value at higher concentrations of ABS. The above observation is true with the increasing dose of irradiation and as the dose of e-beam was increased both flexural strength and flexural modulus were found to decrease. At 300 kGy radiation for 10% ABS concentration, there was a 22% increase in flexural modulus as observed in Fig. 2. Mode of deformation in the flexure of blends of virgin nylon 66 was yielding-type indicative of ductile failure at lower doses of e-beam, and the extent of yielding decreased with the increasing dose of e-beam showing brittle failure. However, when cross linkers were added, the deformation remained ductile throughout the entire range of doses applied.

Fig. 2 Variation of flexural modulus of various nylon 6,6/ABS materials with ABS concentration at different doses of e- beam

As shown in Fig. 3, Surface hardness of nylon 6,6/ ABS blends was increased at the initial concentration of ABS till 10% and thereafter to constant values at the higher concentrations of ABS. On the other hand, increase of 16% Rockwell Hardness was observed at 300 kGy e-beam dose with 10% ABS concentration. The rise in hardness clearly indicates that the polymer turns more rigid at 10% ABS on irradiation by 300 kGy e-beam. Increased rigidity improves the machinability of nylon 6,6/ ABS, which is one of the most desirable characteristics for a plastic material to be used successfully in engineering applications.

Fig. 3 Variation of Rockwell hardness of nylon 6,6/ ABS with ABS concentration at different doses of e- beam.

The results of Izod impact strength for various nylon 6,6 as shown in Fig. 4 revealed that all irradiated blends showed higher impact strength as compared to corresponding unirradiated material. Interestingly, at 10% ABS concentration impact strength increased maximum at all doses of e- beam when compared with unirradiated virgin material. There was an increase of 36% impact strength of nylon 66 when it was blended with 10% ABS and irradiated at 150 kGy e-beam. The improved impact strength at lower percentages of ABS may be due to the presence of an immiscible phase of nylon 6,6 and ABS in the matrix of nylon 6,6. The increase of impact strength on irradiation may be attributed to the cross linking of polyamide chains through iso cyanurate cross linker. At higher doses of e-beam however chain scission might have played an important role in the deterioration of impact strength of all nylon 6,6/ ABS blends.

Fig. 4 Variation of Izod impact strength of nylon 66/ ABS with ABS concentration at different doses of e-beam

The most significant achievement in this study is the decrease of water absorption of nylon 6,6 with increasing percentage of ABS and dose of e-beam and this is much desired as far as the performance property of nylon 6,6 is concerned. Percent water absorption of all nylon 6,6/ABS samples in presence of cross linker TAIC has gradually fallen down with increasing ABS concentration as well as dose of e- beam. Percent water absorption of virgin nylon 66 was reduced by 13% at 300 kGy, whereas there was a maximum of 47% reduction at same radiation dose for 50% ABS blended nylon 6,6. In the study of e- beam irradiation of nylon 6,6 film, Sengupta and co-workers also found that water uptake was less for the films that received a radiation dose of 200 and 500 kGy than the un-irradiated film. Reduction of water absorption may be attributed to the cross linking of polyamide molecules in nylon 6,6. This is further clear from the fact that melt mixing of cross linkers with nylon 6,6 leads to its thermal cross linking resulting in substantial reduction of water absorption even when it was not irradiated with e-beam. The decreasing trend of water absorption with increasing ABS concentration and also with increasing dose of e-


94 :

beam for various nylon 6,6/ ABS compositions is shown in Fig. 5.

Fig. 5 Variation of percent water absorption of nylon 6,6/ ABS blend with ABS concentration at different doses of e-beam

Improvement of mechanical properties and reduction of water absorption of nylon 6,6/ ABS when irradiated by e-beam radiation are due to the cross linking of polyamide molecules in presence of high energy e- beam radiation. Increase of cross linking of nylon 6,6 with increasing e-beam dose may be verified by the increase of gel content. In case of virgin Nylon 6,6, there is no gel formation till 100 kGy, followed by 60% gel formation at 300 kGy as seen in Fig. 6.

Fig. 6 Gel content of nylon 6,6/ ABS blend with ABS concentration at different doses of e- beam

G(s)/G(x) value of virgin Nylon 6,6 was determined from Charles by – Pinner plot as 2.32 while it was decreased to 1.32 for 50 % ABS composition as observed in Fig. 7. This is indicative of the occurrence of more cross linking while cross linkers are incorporated into nylon 6,6. Cross linkers played very important role by accelerating the process of cross linking through the generation of free radicals during irradiation by e-beam. The more the decrease of G(s) / G(x) value, the better is the efficiency of the cross linker to enhance the properties of nylon 6,6 through intermolecular cross linking of the polyamide chains. The change in mechanical properties and water absorption of nylon 6,6 at zero irradiation when cross linker was incorporated into it by melt mixing may be attributed to the thermal cross linking and/or post polymerization of poly-amide molecules occurred during melt mixing. Occurrence of cross linking /

post polymerization has been verified in this study by the increase of gel content in nylon 6,6 with increasing dose of e-beam. This is because the extent of thermal cross linking/ post polymerization of polyamide molecules during melt mixing is not enough to form n soluble and infusible mass of nylon 6,6 gel. This is, however, advantageous as far as the processability of nylon 6,6 is concerned as its processing is not affected by the thermal cross linking / post polymerization during its melt mixing with cross linker. It has been observed in this study that the improvement of most of the properties up to 150 kGy e-beam dose is much significant than that observed beyond 150 kGy. The major improvement of properties and performance of nylon 6,6 at lower doses of e-beam will undoubtedly emphasis more industrial acceptance of radiation processing of this polymer over its conventional processing techniques.

Fig. 7 Variation of G(s)/G (X) of nylon 6,6 system with ABS concentration.

Fig. 8 DSC Thermograms for Nylon 6,6/300KGy at 0, 10, 20 and 50 % ABS concentration

DSC thermograms of nylon 6,6/ABS as presented in Fig. 8 reveal that crystalline melting temperature (Tm) and crystallization temperature (Tc) of nylon 66 at 300 KGy have decreased gradually with the increase of ABS concentration. Tm of nylon 6,6 for (0 ABS) has been reduced from 258 0 C to 253 0 C for 20% ABS while its Tc has been decreased from 229 0C for (0ABS) to 224 0C 20% ABS, when irradiated at 300 kGy dose. The decrease of melting and crystallization temperatures with increasing ABS concentration is due to the reduction of crystallinity of nylon 6,6 in presence of high energy e- beam radiation. The reduction of crystallinity in nylon 6,6/ ABS blends has been verified by the plot of percent crystallinity vs ABS


95

concentration dose as shown in Fig. 9. The decrease of percent crystallinity is indicative of the development of more amorphous nature in nylon 6,6 when irradiated by e-beam.

Fig. 9 Percent crystallinity with dose of e-beam

Morphological changes are observed in nylon 6,6/ABS (50%) blend before and after 300 kGy e- beam when scanned at magnification of 5 K X. Micrographs of unirradiatednylon 6,6/ ABS (50 %) exhibits poor miscibility between nylon 6,6 and ABS leading to a partially miscible & immiscible blend composition. On irradiation by e- beam at higher dose of 300 kGy there occurs cross linking between the polyamide chains through tri allyliso cyanurate cross linker forming an interpenetrating network (IPN) of nylon 6,6 and ABS polymer. SEM micrograph of nylon 6,6/ABS (50%) at 300 kGy verifies a uniform phase distribution of IPN i.ehexa methyl eneadipamide- tri allyliso cyanurate-acrylonitrile butadiene styrene.

(a) 0 kGy (b) 300 kGy

Fig. 10 SEM micrographs of nylon 6,6/ ABS (50 %) before and after 300 kGy e-beam irradiation

Conclusions High energy ionizing electron beam radiation was found to be a unique and powerful means of improving the mechanical properties and overcoming the inherent drawbacks of nylon 6,6. Most importantly the radiation processing technique is highly beneficial since all the changes are brought about in solid-state, as opposed to alternative chemical and thermal reactions carried out in hot, molten polymer.

Physical and mechanical properties improved significantly when nylon 6,6/ ABS irradiated by electron beam in presence of cross linker. This is because of development of cross linked structure in nylon 6,6 induced by e-beam. The cross linked nylon 6,6/ ABS may be useful for resulting in

dimensionally stable articles with superior mechanical properties and improved serviceability.

Decrease of water absorption by e-beam irradiation of nylon 6,6/ ABS blends in presence of cross linker is another important achievement as it helps to reduce the inherent hygroscopic nature of nylon66 resulting in improved dimensional stability and shelf life of the components made from it.

Development of cross-linked structure in irradiated nylon 6,6 was evidenced by the formation of infusible and insoluble gel. It is further verified by the increase of gel content in irradiated nylon 6,6/ ABS with increasing dose of e-beam & ABS concentration. Presence of cross linker has decreased G(S)/G(X) value in irradiated nylon 6,6 indicating more cross-linking than chain scission in irradiated sample than that occurred in virgin nylon 6,6.

Interpenetrating network of Nylon 6,6- TAIC- ABS was formed when nylon 6,6 was blended with ABS in presence of TAIC and irradiated by e- beam. Acknowledgements The authors would like to acknowledge the financial assistance provided by Board of Research in Nuclear Sciences (BRNS), Mumbai for carrying out this research. Authors also acknowledge Shriram Institute for Industrial Research, New Delhi for their support and guidance in conducting this research work. References 1. Kohan M, in Nylon Plastics Handbook, (Gardner

Publications, Inc,New York) Hanser, 1995, 631. 2. Engineering Materials Handbook, Vol. 2,

Engineering Plastics, (ASM International) 1988,883. 3. Sakurada I, Radiat Phys Chem, 14 (1979)23. 4. Bhattacharya A, Prog Polym Sci, 25 (2000) 371. 5. Charlesby A, Nature, 171 (1953) 167. 6. Lawton E J, Bueche A M & Balwit J S, Nature,

172(1953) 76. 7. Zimmerman J, J Polym Sci, 46(1960) 151. 8. Deeley C W, Woodward A E & Sauer J A, J Appl

Phys, 28 (1957)1124. 9. Sengupta R, Tikku V K, Somani A K, Chaki T K &

Bhowmick A K, Radiat Phys Chem, 72(2005) 751. 10. Sengupta R, Sabharwal S, Tikku V K, Chaki T K &

Bhowmick A K, J Appl Polym Sci, 99(2006)1633. 11. Jung C H, Choi J H, Lim Y M, Jeum J P, Kang P H &

Nho Y C, Appl Chem, 10(2006) 421. 12. Dadbin S, Frounchi M & Goudarzi D, Polym Degrad

Stab, 89(2005) 436. 13. Pramanik N K, Haldar R S, Bhardwaj Y K,

Sabharwal S, Niyogi U K & Khandal R K, Radiat

Phys Chem, 78 (2009) 199. 14. Charlesby A & Pinner S H, Pro Roy SocA, 249(1959)

367. 15. Brandrup J, Immergut E H & Grulke E A, in Polymer

Handbook, Vol. 126, 4thedn (Wiley, New York), 1999.



Heat Transfer Enhancement of Three Sides Artificially Roughened

Solar Air Heater

Arun Kumar Behura1, Ashwini Kumar

2, Ravi Kumar

2 & Souren Mishra

3

1Department of Mechanical Engineering, Poornima College of Engineering, Jaipur-302033, India

2Research Scholar, National Institute of Technology, Jamshedpur, India

3Asst. Prof. Department of Mechanical Engineering, NIST, Berhampur, India



Abstract The rate of heat transfer enhances by providing artificial roughness underside of the absorber plate is considered to be an effective technique and leading to higher collector performance. Under the same operating conditions three sides artificially roughened solar air heaters perform better than those of existing one side artificially roughened solar air heaters. Provision of artificial roughness results in a higher friction factor and consequently a higher pumping power is required. Solar air heater duct with three sides artificially roughened has been analysed by the authors for fully developed turbulent flow and found to perform better both quantitatively and qualitatively as compared to the one side artificially roughened solar air heater under the same operating conditions. Top side (one side) roughened solar air heaters are found to have higher values of heat transfer characteristics from the plate as compared to smooth solar air heaters. Three sides roughened and glass covered solar air heaters have been reported to have even better heat transfer characteristics compared to top side roughened ones. This paper deals with the effect of various parameters on temperature and heat transfer characteristics in three sides artificially roughened solar air heaters. Relative roughness pitch, relative roughness height, flow Reynolds number, hydraulic diameter of the solar air heater duct and intensity of solar radiation are the parameters. Air temperature and heat transfer coefficient have been found to increase in the range of 1-9% and 10-40%, over those of one side roughened solar air heaters for the range of parameters investigated whereas, 30-50% and 100-140%, over those of smooth ones. Keywords Relative roughness pitch (p/e), Relative roughness height (e/D), Flow Reynolds number (Re), Average Nusselt number

Artificial roughness is a well-known method to increase the heat transfer by use of regular geometric roughness elements on the surfaces. Use of artificial roughness of different geometries to enhance heat transfer in solar air heaters is widely available. Prasad and Saini1 analyzed for heat transfer enhancement for fully developed turbulent flow in a solar air heater duct with small diameter wires on the absorber plate. Gupta et al.2 used continuous ribs at an inclination of 600 to the air flow direction. Karwa et al.3 used chamfered rib roughness on the absorber plate and found that at low flow rate, higher relative roughness height yields a better performance. Transverse ribs have been used4 to enhance heat transfer coefficient. Wire

mesh roughness5, transverse protrusion wire roughness6, wedge shape ribs7, V-shape ribs8, arc shape roughness9, dimple shape roughness10, combined inclined and transverse ribs11, multi V-rib roughness12, w-shaped ribs13 are the works on analysis and investigations, where appreciable enhancement in heat transfer coefficient has been found quantitatively and qualitatively both. All the above works including reviews of 14-18 and 19-20 have remained limited to only one top side roughened collector having artificial roughness which acts as the absorber plate. The recent works of 21-22 for fully developed turbulent flow in three sides artificially roughened solar air heater for heat transfer and friction factor are available. Three sides artificially roughened solar air heaters with three sides glass covers22 with a large aspect ratio (W >> B) is a novel one, where correlations predict the effect of roughness and flow parameters (p/e, e/D, Re) on heat transfer for fully developed turbulent flow, and

Corresponding Author: Arun Kumar Behura e-mail: [email protected]

ISSN: 2394-3173 (Print)

2395-3225 (Online)

results are found to be even better than one side roughened solar air heaters. The enhancement of heat transfer coefficient attempted by providing artificially roughness, always results in an increment of pressure drop and the requirement of pumping power is increased. However, it results in higher value of thermal performance. This paper deals with the results on temperature and heat transfer characteristics in three sides roughened and glass covered solar air heaters with respect to existing one side roughened solar air heaters.


Three sides artificially roughened solar air heater duct with three sides glass cover and one side artificially roughened duct with top side glass cover only have been developed. The two ducts have been provided with similar roughness parameters, connected with a single blower to run simultaneously under actual outdoor conditions. Fig. 1 shows the schematic of the experimental set up with solar air heater ducts A and B which are one side roughened and three sides roughened respectively. The two ducts are similar in dimensions as those of 21 which are 2000 mm long, 200 mm wide and 25 mm height. In both of one side and three sides artificially roughened solar air heater ducts, only 1500 mm of the duct length acts as the test section and remaining 500 mm as the flow stabilization bell-mounted entry section. The solar collector of the entry section was prevented from the solar radiations. Artificial roughness have been provided on the fluid flow side of the absorber plate normal to the fluid flow direction at varying values of relative roughness pitch, p/e, in the range of 10-20, relative roughness height, e/D, in the range of 0.0315-0.0247. Flow Reynolds number, Re, varied in the range of 5000-13000 and intensity of solar radiation, , varied in the range of 740-920. Artificial wire roughness provision transverse to the fluid flow direction is shown in Fig. 2 and 3 at pitch diameter of p, whereas e is the diameter of the wire.

A-One side roughened duct B-Three sides roughened duct

1. Hydraulic entry length 2. Test section 3. Orifice-meter 4. Blower

Fig. 1 Schematic of experimental set-up

Fig. 2 Top absorber plate for both one side and

three sides artificially roughened duct

Fig. 3 Side absorber plates for three sides artificially

roughened duct

Results and discussion

Studies of artificially roughened solar air heater duct predominantly concerned with the effect of shape and arrangement of roughness elements on heat transfer requirement comparative assessment. The raw experimental data were collected for the three sides artificially roughened solar air heater duct and one side artificially roughened solar air heater duct simultaneously. The value of the hydraulic diameter, D, of the similar size solar air heater ducts for both three sides and one side artificially roughened solar air heater duct has been worked out to be 44.4 mm. Fig. 4 shows the variation in the plate, fluid and inlet air temperature in three sides roughened and one side roughened solar air heaters along the collector flow length. Fig. 5 shows that the variation of the average plate temperature and average fluid temperature with respect to the intensity of solar radiation, both are higher in three sides roughened collector than those in one side roughened collector.

0 10 20 30 40 50

28

30

32

34

36

38

40

it

ft

pt

L/D

Inlet temperature of fluid for one side and three side roughened duct

Plate temperature for three sides roughened duct

Plate temperature for one side roughened duct

Fluid tempearature for three sides roughened duct

Fluid tempearature for one side roughened duct

Fig. 4 Variation of plate, fluid and inlet

temperature

97 Behura A K, Kumar A, Kumar R & Mishra S: Heat Transfer Enhancement of Three Sides Artificially Roughened Solar Air Heater

740 760 780 800 820 840 860 880 900 920

32

34

36

38

40

42

44

ft

Average plate temperature for three side rough

Average plate temperature for one side rough

Average fluid temperature for three side rough

Average fluid temperature for one side rough

I

pt

Fig. 5 Variation of average temperature of plate and fluid

Heat Transfer data

Raw experimental data have been reduced using relevant equations to obtain the values of resulting parameters. The analytical values of Nusselt number, , for one side roughened collector have been worked out using Eqn. (1) of (Prasad and Saini, 1988), written under:

(√ )*

+

(1)

whereas, the analytical values of Nusselt number, , for three sides roughened solar air heater have been found out by Eqn. (2) of (Prasad et al. , 2014), written under:

(

)

(2)

The experimental values of heat transfer coefficient for one side and three sides artificially roughened collectors have been worked out using Eqn. (3) written under: (3) which have further been used for calculating the values of Nusselt number for one side and three sides roughened collector using Eqn. (4) written under:

(4)

Fig. 6, 7 and 8 represent the values of respective Nusselt number for the present case and those of (Prasad, 2013; Prasad et al., 2014) and shows the comparison of heat transfer data for given value of relative roughness pitch, p/e, equal to 10, 15 and 20 respectively and relative roughness height, e/D, equal to 0.0247, for the range of flow Reynolds

number. Since, the values of heat transfer compare well within the range of parameters investigated, results have been further represented to see the effect of various parameters on heat transfer. Fig. 9 has been shown to see the effect of roughness and flow parameters on heat transfer enhancement in three sides roughened solar air heater in comparison to one side roughened solar air heater and also compared with existing smooth solar air heater. Fig. 9 shows the effect of relative roughness height, e/D, on

, for three sides roughened collector, , for one side roughened collector, and , for smooth solar air heater, for a given value of relative roughness pitch, p/e, equal to 10 at varying values of flow Reynolds number. The values of Nusselt number,

, for three sides roughened collector enhance by an amount of 20-50% over those of , for one side roughened collector and enhances by an amount of 110-160% over those of , for smooth collector.

2000 4000 6000 8000 10000 12000

10

20

30

40

50

60

70

80

p/e=10 and e/D=0.0247

(2)

(1)

rNu

Nu

Re

(1) (Prasad et al., 2014)

(2) (Prasad and Saini,1988)

(Prasad, 2013) Expt. Work for one side rough

Present Expt. Work(three side rough)

Present Expt. Work (one side rough)

Expt. work for smooth duct (Prasad, 2013)

sNu

Fig. 6 Comparisons of heat transfer data at p/e =10

2000 4000 6000 8000 10000 12000

10

20

30

40

50

60

70

80

rNu

Nu

p/e=15 and e/D=0.0247

(1)

(2)

Re


Present Expt. work (three side rough)

Present Expt. work (one side rough)

(2) Analytical values of smooth duct (Prasad, 2013)

sNu

Fig. 7 Comparisons of heat transfer data p/e =15


2000 4000 6000 8000 10000 12000

10

20

30

40

50

60

70

80p/e=20 and e/D=0.0247

sNu

rNu

Nu

(2)

(1) (1)

Re


(2) (Prasad and Saini, 1988)

Prasad(2013) Expt.Work

Present Expt. work (three side rough)

Present Expt. work (one side rough)


Fig. 8 Comparisons of heat transfer data p/e =20

2000 4000 6000 8000 10000 12000

10

20

30

40

50

60

70

80

p/e=10(constant) for different e/D

Re

e/D=0.0247

e/D=0.0225 Present Expt. work (three sides rough)

e/D=0.0135

e/D=0.0247

e/D=0.0225 Present Expt. work (one side rough)

e/D=0.0135


sNu

rNu

Nu

Fig. 9 Effect of e/D on heat transfer data Conclusions

Results on heat transfer for three sides artificially roughened solar air heater duct, one side artificially roughened solar air heater duct and smooth solar air heater duct compare well with the analytical values. Nusselt number for three sides artificially roughened solar air heater enhance under the same operating conditions of mass flow rate and intensity of solar radiations with the increasing values of flow Reynolds number, relative roughness pitch, p/e and relative roughness height, e/D over those of one side roughened solar air heaters and smooth solar air heaters. The values of Nusselt number for three sides roughened collector have been found to increase by an amount 20-50% in comparison to one side roughened collector whereas, 110-160% in comparison to the smooth collector within the same range of the values of the roughness and flow parameters investigated.

Nomenclature

collector area, m2 Cp specific heat at constant pressure of air,

KJ/Kgk hydraulic diameter of solar air heater duct, m e artificial roughness height, m

e/D relative roughness height

roughness Reynolds number √(

)

friction factor in four sided smooth duct average friction factor in three sides

roughened duct average friction factor= , in one

side roughened collector friction factor in four sided rough duct convective heat transfer coefficient, W/m2 K intensity of solar radiation, W/m2

k thermal conductivity of collector material, W/m K

mass flow rate of air, Kg/s average Nusselt number for three sides

roughened collector average Nusselt number for one side

roughened collector Nusselt number Nusselt number for four sided smooth

collector roughness pitch, m

relative roughness pitch Prandtl number

Flow Reynolds number inlet temperature of air, K outlet temperature of air, K average temperature of fluid, K average temperature of plate, K

References 1. Prasad B N & Saini J S, Solar Energy, 41 (1988) 555. 2. Gupta D, Solanki S C & Saini J S, Solar Energy, 61

(1997) 33. 3. Karwa R, Solanki S C &Saini J S, Int J Heat Mass

Transf, 42 (1999) 1597. 4. Gupta D, Solanki S C & Saini J S, Solar energy, 51

(1993) 31. 5. Saini R P & Saini J S, Int J Heat Mass Transf,

40(1997) 973. 6. Verma S K & Prasad B N, Renewable Energy, 20

(2000) 19. 7. Bhagoria J S, Saini J S & Solanki S C, Renewable

Energy, 25 (2002) 341. 8. Momin A M E, Saini J S, Solanki S C, Int J Heat

Mass Transf, 45(2002) 3383. 9. Saini S K & Saini R P, Solar Energy, 82(2008) 1118. 10. Saini R P & Verma J, Energy, 33 (2008) 1277. 11. Varun, Saini R P & Singal S K, Renewable Energy,

33(2008) 1398. 12. Hans V S, Saini R P & Saini J S, Solar Energy, 84

(2010) 898. 13. Lanjewar A M, Bhagoria J L & Sarviya R M,

Journal of Experimental Thermal and Fluid Science, 35(2011) 986.

99 Behura A K, Kumar A, Kumar R & Mishra S: Heat Transfer Enhancement of Three Sides Artificially Roughened

Solar Air Heater

14. Chamoli S, Chauhan R, Thakur N S & Saini J S, Int Journal of Renewable and Sustainable Energy Reviews, 16 (10)(2012) 481.

15. Gawande V B, Dhoble A S & Zodpe D B,. Renewable and Sustainable Energy Reviews, 32(2014)347.

16. Saurav S & Sahu M M, Int. J Renewable Energy

Research, 3(3) (2013) 498. 17. Shakya U, Saini R P & Singhal M K, Int J Emerg

Technol and Adv Engg, 3(6) (2013) 279.

18. Bhushan B & Singh R, Energy, 35(2010) 202. 19. Bhushan B & Singh R, Int Journal of Solar Energy,

86 (11) (2012) 3388. 20. Yadav A S & Bhagoria J L, Int J Heat Mass Transf,

70(2014) 1016. 21. Prasad B N, Solar Energy, 91(2013) 59. 22. Prasad B N, Behura A K & Prasad L, Solar Energy,

105 (2014) 27.


Applied Science and Advanced Materials International Vol. 2 (4-6), March - August 2016, pp. 101 – 105

Speaker ID recognition using Quasi-Stationary speech Signal Processing

Madhusmita Mohanty

1*, Kaushik Mohanty

1, Madhumita Dash

2, Gayadhar Pradhan

3

1Department of ETC, Orissa Engineering College, Bhubaneswar

2 Department of ETC, Spintronic Technology & Advance Research, Bhubaneswar

3 Department of ECE, NIT, Patna, Bihar


Orissa Engineering College, Bhubaneswar, India, 04-05March, 2016

Abstract The purpose of this paper is to select slowly time varying speech sample (it is called quasi stationary) to identify a speaker. Usually, a few seconds of speech are sufficient to identify a familiar voice. Automatic speaker recognition works on the premise that a person‟s speech exhibits characteristics that are unique to the speaker. The idea to assist the machine, to recognize humans from their voices is quite evident. Speaker recognition is the process of automatically recognizing who is speaking on the basis of individual information included in speech signal. However this task has been challenged by the highly variant of input speech signals. In this e-world, it may be possible to use it for speaker identification and authentic accession in various fields like banking by telephone, telephone shopping, database access services, voice dialing, security control for confidential information areas, and remote access to computers. Another important application of this technology is for forensic purposes, where the voice of the criminal and the voice of the suspect need to be verified as the same from a recorded message. The purpose of this paper is to convert the speech waveform, using digital signal processing tools in matlab, to a set of features (at a considerably lower information rate) for further analysis. When examined over a sufficiently short period of time, its characteristics are fairly stationary. However, over long periods of time the signal characteristic change to reflect the different speech sounds being spoken. Therefore, short-time spectral analysis is the most common way to characterize the speech signal. A wide range of possibilities exist for parametrically representing the speech signal for the speaker recognition task, such as mel frequency cepstral coefficient (MFCC) is the best known and most popular, and will be described in this paper which shows the result of speaker ID matching. Keywords Speech analysis, Cepstral coefficient, Feature extraction, Performance evaluation, Speaker ID matching Speech communication is one of the natural forms of voice signal i.e. recent developments had made it possible to use this in security systems. Calculation of mel frequency cepstral coefficient (MFCC) is based on the human auditory system aiming for artificial implementation of the ear physiology. Assuming that the human ear can be a good speaker recognizer too. Computation of MFCC involves averaging the low frequency region of the energy spectrum by closely spaced overlapping triangular filters while smaller number of less closely spaced filters with similar shape are used to average the high frequency zone1. In speaker identification, the task is to use a speech sample to select the identity of the person that produced the speech from among a population of speakers. When examined over a sufficiently short period of time (in few msec), of speech signal Corresponding Author: Madhusmita Mohanty email:[email protected] Ph: 9861048047

Fig. 1 Plot of speech signal sound(s1.wav) in matlab, its characteristics are fairly stationary as shown in Fig. 1. However, over long periods of time (on the order of 1/5 seconds or more) the signal characteristic change to reflect the different speech sounds being spoken1. Therefore, short-time spectral analysis is the most common way to characterize the speech signal. MFCC‟s are based on the known variation of the

ISSN: 2394-3173 (Print)

2395-3225 (Online)


human ear‟s critical bandwidths with frequency; filters spaced linearly at low frequencies and logarithmically at high frequencies have been used to capture the phonetically important characteristics of speech. This is expressed in the mel-frequency scale, which is a linear frequency spacing below 1000 Hz and a logarithmic spacing above 1000 Hz2,3. Experimental

Analysis Stage

Since speech is a non-stationary signal, it is processed in frames to perform short term analysis. It is processed by the following blocks shown in Fig. 2.

Fig. 2 Block diagram of MFCCs Computation In this step the continuous speech signal is blocked into frames of N samples, with adjacent frames being separated by M (M < N)4. The first frame consists of the first N samples as shown in Fig. 3. The second frame begins M samples after the first frame, and overlaps it by N - M samples and so on. This process continues until all the speech is accounted for within one or more frames. Typical values for N and M are N = 256 (which is equivalent to ~ 30 msec windowing and facilitate the fast radix-2 FFT) and M = 100. For this work, we are using hamming window.

---------------------(1) Using equation (1) Hamming Window coefficients are generated with which corresponding speech of frame is scaled5. But due to hamming windowing, samples present at the verge of window are weighted with lower values. In order to compensate this, generally frames are overlapped by 50%. For the present work a windowed speech frame of size 15 ms(160 samples for 8 kHz Signal) with a shift of 10 ms (80 samples for 8 kHz Signal)is taken to extract vocal tract information.

-----------------------(2) Using equation (2), the square of the response of the signal is extracted where N is the no of samples & k is the no of points.

Fig. 3 DFT spectrum for one frame of speech signal. (a) hamming windowed speech signal, (b) DFT spectrum

Mel frequency spectrum

A mel is a unit of measure of frequency of a tone. Since the human auditory system perceives on a nonlinear scale, the Mel frequency scale can be used to extract the spectral information and is related to linear frequency by the following relation

------------------------(3) Using above equation (3) a spectrum is constructed with critical bands which are overlapped triangular filter banks, the linear spaced frequency spectrum (fHz) is mapped into nonlinearly spaced frequency spectrum (fMel). Since the spectrum is symmetric about half of sampling frequency, the spectrum up to 4 kHz for present case is considered and other half is replica of this. The energy spectrum is then mel-frequency warped to mimic human ear. For the present case the spectrum is symmetric about 4 kHz which is equivalent to 2146 mel in this mel scale. This mel scale is divided into Q (22 for present case) equally spaced unit height triangular filters and is shown in Fig. 4. The center frequency of each filter is calculated in mel scale6. The linear frequency corresponding to each mel center frequency is computed and the filters are constructed in linear frequency domain as is shown in Fig. 3. The frequency response of mth triangular filters are shown in a Fig. 4.

102

Mohanty M, Mohanty K, Dash M, Pradhan G: Speaker ID recognition using Quasi-Stationary speech Signal Processing

Fig. 4 Critical band filters for mel-frequency warping in mel scale.

Fig. 5 Frequency response of triangular filter For any point “K” lies in the left half of the triangle (Fig.5) the filter response is calculated as follows. The slope of the left side arm of the triangle is given by,

-------------------------------------(4) The point “K” whose co-ordinate with respect to origin (K, 0) and is (k − Cm, 0) with respect to starting point of triangle is mentioned in equation (4). The filter response at K is the corresponding Y co-ordinate, which lies on the line having slope m.

---------------------------------------(5) Hence the frequency response is calculated by using the following equation (6) y = m × x -------------------------------------------(6) This filter bank is imposed on the spectrum calculated in equation (7). The outputs e(i) for i=1 to Q of the Mel-scaled band pass filters can be calculated by a weighted summation between respective filter response i(k) and the energy spectrum |X(k)|2.The energy spectrum of e(i) is

-------------------------------(7) Log magnitude spectrum of equation (7) is taken to satisfy the concept of cepstral analysis as follows

-----------------------------------(8) Where „Q‟ is the no of filter banks. Finally, IDCT is taken on the log filter bank energies of equation (8) and the final MFCC coefficients C(m, n) is calculated as follows.

(n- -------------(9)

Therefore if we denote those mel power spectrum coefficients that are the result of the calculation of Mel frequency coefficients in equation (9). The first component is excluded from the DCT since, it represents the mean value of the input signal, which carried little speaker specific information. After this session, the acoustic vectors extracted from input speech of each speaker provide a set of training vectors for that speaker7.

Generation of codebook As described above, the next important step is to build a speaker-specific vector quantization (VQ) codebook for each speaker using those training vectors. There is a well-know algorithm, namely Linde-Buzo-Gray (LBG) algorithm for clustering a set of training vectors into a set of M codebook vectors. The algorithm is formally implemented by the following recursive procedure: (i). Design a 1-vector codebook; this is the centroid of the entire set of training vectors (hence, no iteration is required here). (ii). Double the size of the codebook by splitting each current codebook according to the rule

)1(

nn yy , )1(

nn yy where n varies from 1 to the current size of the codebook, and is a splitting parameter (we choose =0.01) Intuitively, the LBG algorithm designs an M-vector codebook in stages. It starts first by designing a 1-vector codebook, then uses a splitting technique on the code words to initialize the search for a 2-vector codebook, and continues the splitting process until the desired M-vector codebook is obtained8,9. In this project, the VQ approach will be used, due to ease of implementation and high accuracy. VQ is a process of mapping vectors from a large vector space to a finite number of regions in that space. Each region is called a cluster and can be represented by its center called a codeword. The collection of all code words is called a codebook.

103

Fig. 6 Code book of speaker 1& speaker 2 Result in matlab The system initially requires the pre-recorded speech file. In latter stages, the system will use recorded audio from multiple users. This will require a microphone for input which will store the signal temporarily while the system analyses it against stored users. In the final stages of the project, the system will wait for a prompt to start recording10,11. The system will then wait for audio silence to stop analyzing. This audio silence will then be removed from the signal and then be analysed as usual. A codebook vector of speaker1 & speaker2 is generated after processing the signal through matlab is shown in Fig. 6. The goal of pattern recognition is to classify objects of interest into one of a number of categories or classes8. The objects of interest are generically called patterns and in our case are sequences of acoustic vectors that are extracted from an input speech. The classes here refer to individual speakers4.

Fig. 7 Sound added for speaker1

Fig. 8 Sound added for speaker2

Fig. 9 Speaker ID matching Since the classification procedure in our case is applied on extracted features, it can be also referred to as feature matching. A speaker-specific threshold is also computed from the training samples. After adding sound to the speaker1 the resulting figure window shows the database with sound as shown in Fig. 7. In the testing phase, the input speech is matched with stored reference model(s) and a recognition decision is made as shown in Fig. 8 & 9. However this task has been challenged by the highly variant of input speech signals. The principle source of variance is the speaker himself/herself.


Mohanty M, Mohanty K, Dash M, Pradhan G: Speaker ID recognition using Quasi-Stationary speech Signal Processing

Conclusions The speech signal is passed into the front end processor (FEP), and matlab reads the input speech from a binary format file, or other audio file formats depending on what functions are used in matlab to open such file next. The frame length, sampling frequency, and number of channels which are required are passed into a function to compute a matrix of mel filters which will be used with the input signal to analyse the data. The characteristics of such speech signals are relatively stationary over short periods of time. Over longer periods of time an overflow of speech input makes extracting data more difficult. The first step in the testing stage is to extract features from the input speech and compare the input speech to all other stored templates. Then select the most accurately matching template and ID of the speaker.

Acknowledgement The Authors are very thankful to NIT, Patna & R&D centre of OEC for their help during the process in Matlab to improve the manuscript.

References 1. Saeed K & Nammous M K, ieee trans industrial

electronics, 54(2) (2007) 887.

2. Kawahara H, Katsuse I M & Cheveign A, Speech Comm, 27(3) (1999) 187.

3. Stylianou Y, ieee Trans Speech Audio Process, 9(1) (2001) 21.

4. Degottex G, Lachantin P, Roebel A & Rodet X, Speech Comm, 55(2) (2013) 278.

5. Wang D L & Brown G J, ieee tr neural networks, 10(3) (1999) 684.

6. Wang Y & Gales M J F, ieee Trans on Audio,

Speech, and Language Processing 20(7) (2012) 2149.

7. Zhang S X & Gales M J F, ieee Transactions

Audio Speech and Language Processing, 21(3) (2013) 544.

8. Dehak N, Kenny P, Dehak R, Ouellet P & Dumouchel P, ieee Trans Acoust Speech Signal

Processing, 19(4) (2011) 788. 9. Zen H, Braunschweiler N, Buchholz S, Gales M

J F, Knill K., Krstulovic S & Latorre J, ieee

Trans on Audio, Speech, and Language

Processing, 20(6) (2012) 1713. 10. Lippmann R P, Speech Comm, 22(1) (1997) 1. 11. Cooke M & Ellis D P W, Speech Comm, 35(3)

(2001) 141.

105


Erosion wear behavior of Aluminum-1Magnesium-5Silicon Carbide Composite

produced by Modified Stir Casting Method

Birajendu Prasad Samal*

Mechanical Engineering Department, Orissa Engineering College, Bhubaneswar.



Abstract Particle reinforced metal matrix composites (MMCs) are now recognized as important structural materials. Therefore, in the present study a new approach to aluminum metal matrix composites (AMMC) production has been proposed. Aim of the present work was to modify the stir casting method by introducing silicon carbide particles at the bottom of liquid melt (Al) so that its effectiveness would be improved as well as to introduce magnesium chips to the aluminum melt with high recovery of magnesium. The Al-1Mg-5SiC MMC prepared by modified stir casting method was tested for erosion wear in the present work. An erosion apparatus of the „sand blast‟ type is used where particles under desired pressure are impinged onto a stationary target. Erosion wear can be conducted over a wide range of particle sizes, velocities, particles fluxes and incidence angles, in order to generate quantitative data on materials and to study the mechanisms of damage. The test was conducted as per ASTM G76 standards. Statistical methods have commonly been used for analysis, prediction and/or optimization of a number of engineering processes. The present work addresses to this aspect by adopting a systematic statistical approach called Taguchi method to optimize the process parameters.

Keywords Erosion wear, Metal matrix composites, Taguchi method

Aluminum metal matrix composites (AMMCs) refer to the class of light weight high performance aluminum centric material systems. The reinforcement in AMMCs could be in the form of fibers, whisker or particulates, in volume fractions ranging from a few percent to 70%. Properties of AMMCs can be tailored to the demands of different industrial applications by suitable combinations of matrix, reinforcement and processing route1. The aim of the present work is to investigate the erosion wear behavior of Aluminum-1wt% Magnesium reinforced with 5wt% Silicon Carbide developed by modified stir casting method. Solid particle erosion on Al-1Mg-5SiC is conducted using sand particles. Implementation of statistical techniques (through Taguchi and statistical techniques) in analyzing the erosion behavior of composites is made. The objectives of the present

investigation are to determine the solid particle erosion wear rate by calculating the cumulative mass loss of the Al-1Mg-5SiC composite. Erosive wear can be defined as metal removal due to impingement of solid particles on the material surface. The erosion wear rate is said to be dependent on certain parameters which control the erosion wear process of the material surface. These process parameters are: (1) Angle of impingement, (2) Impingement velocity, (3) Standoff distance, (4) Nature of Erodent, (5) Material properties. The Taguchi method is a powerful tool for designing high quality systems based on orthogonal array (OA) for designing the experiments with an optimum setting of process control parameters2-6.


The Al-1Mg-5SiC composite has been fabricated by stir casting technique which has been published else where7. A modified stir casting technique for preparation of the Al-Mg alloy is designed using low cost scrap Mg, using a plunger for making the alloy addition. Then the reinforcement SiC particles

Corresponding author: Birajendu Prasad Samal, e-mail: [email protected] Phone: 9861040013

ISSN: 2394-3173 (Print)

2395-3225 (Online)


are added in the similar manner. The melt is poured into molds and cooled. Then samples of the required dimensions are cut for the erosion wear test. An erosion apparatus of the „sand blast‟ type is used where particles under desired pressure are impinged onto a stationary target. The test was conducted as per ASTM G76 standards. Samples of size 25mmX 25mm X 3mm were cut and polished for erosion wear test. A systematic statistical approach called Taguchi method was used to optimize the process parameters and save time. The erosion wear tests on the composites are carried out under different operating conditions considering three parameters, viz., impact velocity, standoff distance and impingement angle each at four levels as listed below in accordance with Taguchi‟s L16 orthogonal array. The impacts of these three parameters are studied using this L16 array and the tests are conducted as per this experimental design. The experimental observations are further transformed into signal-to-noise (S/N) ratios. The S/N ratio for minimum wear rate can be expressed as “smaller is better” characteristic. This aims to minimize the erosion of Al-1%Mg-5%SiC by optimizing the tribological testing parameters with the help of Taguchi method. The influence of testing parameters like angle of impingement, velocity of impingement and stand-off distance together with their interactions on the erosion behavior of Al-Mg-10% SiC is studied.

The conditions under which erosion tests were carried out are given below Erodent - Silica sand Erodent size (μm) - 150–250 Impingement angle α (0) - 30, 45, 60, 90 Impact velocity (m/ s) - 15, 45, 60, 75 Erodent feed rate (g/min) - 12.5 Test temperature - Room Temp. Nozzle to sample distance (SOD) (mm.) - 10, 20, 30, 40 Erosion wear rate was calculated as Wear rate = Mass loss from sample due

to erosion/Mass of erodent used


The erosion rates for different process parameters combination with different levels were measured and the results were given in Table 1. The optimization of process parameters was done using MINITAB software. The effect of the angle of impingement (300,450,600,900) on the erosion rate of the Al-1Mg-

5SiC metal matrix composite when subjected to solid particle (sand) erosion are illustrated in Table 1.

Table 1 Erosion Rate(ER) for L16 (OA)

Impact Angle

(degree)

SOD (mm)

Impact Velocity

(m/s)

Erosion Rate

(mg/Kg) 30 10 15 76.428 30 20 45 170.667 30 30 60 185.476 30 40 75 286.587 45 10 45 100.238 45 20 15 51.619 45 30 75 186.476 45 40 60 115.793 60 10 60 135.793 60 20 75 137.875 60 30 15 50.492 60 40 45 85.238 90 10 75 168.222 90 20 60 106.111 90 30 45 60.428 90 40 15 37.476

It can be observed from the table that the erosion rate increases with increase in the angle of impact irrespective of the impingement velocities. The erosion wear rate is higher at 900 angle of impact and minimum at 30o angle. As the maximum erosion occurs at higher angles, it can be said that the erosion occurs by ductile mechanism. The study of the relationship of the impingement angle on the mechanism of erosion wear was stated that the normal and tangential components of velocity of the erodent particles can be separated and separately control the wear mechanism. It has been said that when particles strike the sample surface at a particular angle, the tangential component of particle velocity results in plastic deformation of the composite8,9. It can be seen from the table that erosion rate is higher at greater velocities. Because greater the velocity, greater is the kinetic energy of the particles10. It can also be seen from table 1 that the erosion rate decreases with the increase in the standoff distance. This can be attributed to the fact that increasing the standoff distance increases the path traveled by the erodent particles before striking the surface. Thus, the particles lose much energy before striking the surface. As the striking velocity is lowered, the erosion rate is also reduced. It can also be observed that the change in the erosion rate with the SOD is not very significant 9,10,11.

107 2016

Samal B P: Erosion Wear Behavior of Aluminum-1Magnesium-5Silicon Carbide Composite Produced by Modified Stir Casting Method

108

Fig. 1 Relative Effect of process parameters on erosion wear with smaller is better Table 2 Analysis of Variance for ER, using

Adjusted SS for Tests Source DF Seq SS Adj SS Adj MS F P Angle 3 18539.6 18539.6 6179.9 7.94 0.016 SOD 3 481.5 481.5 160.5 0.21 0.889 V 3 41723.4 41723.4 13907.8 17.86 0.002 Error 6 4672.4 4672.4 778.7 Total 15 65416.9 S = 27.9057 R-Sq = 92.86% R-Sq(adj) = 82.14%

Fig. 2 Optimization curve Using Taguchi experimental design for L 16 model and referring Table 1&2 as well as Figure 1&2

gives the optimum result for minimum erosion rate. Conclusions

It is well known that Taguchi method is one most accepted tool for minimizing the experimental conditions, which gives the idea of the rating of operating factors. In our study we found that for minimum erosion rate the process parameters are angle-64.940, SOD-40mm, and velocity-15 m/s (Fig. 2). All the above observations imply that the material can be a suitable for some mechanical components used in automobiles applications.

References

1. Surappa M K, Sadhana , 28 (2003) 319. 2. Peace G S, Taguchi Methods (Addison-Wesley

Publishing Company, USA) (1993) 52. 3. Lochner J H & Matar J E, Designing for Quality.

(ASQC Quality Press, USA) (1990) 71. 4. Fowlkes W Y & Creveling C M, Engineering

Methods for Robust Product Design (Addison-Wesley Publishing Company, USA) (1995) 23.

5. Park S H, Robust Design and Analysis for

Quality Engineering (Chapman & Hall, London) (1996) 54.

6. Phadke M S, Quality Engineering Using Robust

Design (Prentice-Hall, USA) (1989) 15. 7. Samal B P, Misra A K, Panigrahi S C, Sarangi

B & Mishra S, J of Materials and Metallurgical

Engineering, 3 (2013) 1. 8. Rattan R & Bijwe J, Wear, 262(5–6) (2007) 568. 9. Pool K V, Dharan C K & Finnie I, Wear,

107(1) (1986) 1. 10.Alahelisten A, Hollman P & Hogmark S, Wear,

117 (1994) 159. 11.Sahin Y, Wear, 25 (2005)1717.



The Role of Big Data in Inclusive Growth: An Overview

Tapas Ranjan Baitharu & Subhendu Kumar Pani*

Department of Computer Science and Engineering, Orissa EngineeringCollege, Bhubaneswar, Odisha



Abstract Big data rupture upon the scene in the initial decade of the 21st century, and the first associations to embrace it were online and startup firms. Arguably, firms like Google, eBay, LinkedIn, and Face book were built around big data from the beginning. They didn‟t have to integrate big data with more traditional sources of data and the analytics executed upon them, because they didn‟t have those traditional forms. They didn‟t have to merge big data technologies with their traditional IT infrastructures because those infrastructures didn‟t exist. Institutions, governments, donors, and NGOs are rapidly talking about „inclusive growth‟. This point is in some ways an attempt to address the deficiencies of prioritizing solely economic growth, and an effort to ensure instead that the benefits of growth are more broadly experienced. In this paper we discuss an overview of the inclusive growth introducing the idea that while attempts to tackle inequality and poverty and promote growth can be mutually reinforcing, this link is not automatic. Keywords Big data, Inclusive growth, eBay, LinkedIn, Face book Institutions, governments, donors, and NGOs are rapidly talking about „inclusive growth‟. This point is in some ways an attempt to address the deficiencies of prioritizing solely economic growth, and an effort to ensure instead that the benefits of growth are more broadly experienced. The inclusive growth discuss introduces the idea that while attempts to tackle inequality and poverty and promote growth can be mutually reinforcing, this link is not automatic1. The discuses are happening alongside parallel discussions on sustainability and the co-benefits and trade-offs of sustainable and inclusive growth2. The association between growth, inequality and poverty decline are long contested and therefore their tasks in “inclusive growth” are equally unsettled. Various institutions have traditionally adopted quite different stances.

With regards to growth and poverty, the World Bank, for example, focuses on a soaring pace of growth as a pre-requisite for achieving poverty reduction, whereas IPC-IG avoid presuming a connection between economic growth and levels of inclusion. The confluence of Internet-related movements including e-services (e.g. e-gov, social networks) and the increasing number of smart devices are guiding to a huge volume of data ("big data"). This exponential data development along with cloud computing and data analytics signal a shift towards a socio-economic model, in which data are an important asset driving innovation, inclusive growth and development3, 4. The new potential of data ranges from better informing decision-making to automating knowledge intensive methods and has wide policy implications, many of which are crucial to developing economies. These range from issues related to Internet infrastructure to the rights of the individuals. In particular the right to privacy and to data protection are amongst the major issues that need to be considered in the context of „big data‟ and a careful balance has to be achieved in fully enabling the socio-economic assistances while respecting the right to privacy of each and every individual who is behind the data.

Corresponding Author: Suvendu Kumar Pani e-mail: [email protected] Ph: 9776503280

ISSN: 2394-3173 (Print)

2395-3225 (Online)


110

Three main aspects of global data cooperation and collaborative knowledge creation for developing economies are discussed below: 1.) Global access to data for improved policy making. 2.) Access to data analytics capacities located in other countries. 3.) Privacy and protection. Inclusive Growth in the Digital Economy

The developing digital economy has primarily changed the way we live, work, govern, and express ourselves. Among the lots of outcomes of that change is our undeniable dependence for economic production and improvement on modern communications and everything it enables5. First period of 2011, the global digital economy‟s impact on GDP growth in G7 countries had already exceeded that of other global sectors, such as energy and agriculture, and it is quickly transforming the emerging markets that are the key to future growth and globally shared prosperity. Three billion people are attached to the Internet today. And trillions of devices are set up to connect them in the Internet of Things. Together, that connectivity holds the potential to lift people out of poverty, formalize the informal economy around the world, raise the efficiency of supply chains, increase the productivity of workers, and in turn raise wages and make possible activities that we have not even dreamed up yet6. But it will acquire open markets, the cooperation of leaders around the world, the sharing of a vibrant and diverse range of stakeholders, and strong trade agreements, with language preserving the free flow of information, to protect the Internet‟s potential as the world‟s engine for upcoming growth. And for it to truly succeed, these policy approaches will need the buy in of leaders from the rising economies we want to help in growing. We cannot impose these ideas on them; we have to encourage them of the merits. We believe that this new standard represents a tremendous chance to accelerate social and economic development, but it is incumbent upon all of us to ensure that it develops in a way that is inclusive and for the benefit of all. Wide-ranging approximate calculation suggest that more than half the world‟s population remains offline, and that offline population is focused among the poor populations who will not be reached purely by business expansion of digital offerings. We all have to work together to produce the right policy, legal, and regulatory space worldwide essential to bridge the digital divide and drive the benefits of the digital economy deeper into our societies.

A really inclusive digital economy will make sure that all populations have access to technology, and no singular group is excluded due to barriers such as prohibitively high costs, lack of network connectivity, or social or cultural hurdles. Achieving this inclusive digital economy is going to take a focused attempt of governments, both multilaterally and bilaterally, the ICT industry and the multi-stakeholder community all working together7,8. Important factors for achieving inclusive growth

Some recipes for inclusive growth include many familiar elements from standard growth strategies such as macroeconomic stability and economic openness. This is not astonishing when some institutions and government see achieving high growth rates as the major contributing factor and prerequisite for achieving inclusive growth. Investment in human capital

Investment in human capital is globally recognized as a key pillar of achieving inclusive growth. Investments in health and education have been statistically linked to better economic development outcomes and to how inclusive growth is in practice. As labor is their main asset, a good level of health and education enables poor men and women both to participate in and benefit from economic growth9. Investment in health is also a vital component of human capital. Inequality in health has a significant impact on economic growth, possibly through effects on labor productivity. The cost of poor health also has major impacts on a county‟s economy. Poor sanitation, for example, is estimated to cost Zambia 1.3% of its annual GDP44 - a significant amount when one considers that mining, the most important recipient of FDI in Zambia, contributes only 2.2% to GDP.

Job creation

In order to assist generate more and better jobs for development, job strategies would use extra tools such as fostering entrepreneurship, developing basic skills, strengthening labor institutions and mature approaches to industrial relations, as well as less conventional measures like protecting jobs when large numbers of these are at stake, and targeted support for sectors important for job creation to ensure that gains and spillovers are realized. Structural transformation and broad-based growth For most developing countries, the route to inclusive growth lies in shifting to more productive economic activities (structural transformation). This


111

decreases an over-reliance on a few sectors which in turn increases stability and can generate more and better jobs. Without economic transformation, the poor will remain locked into low-return activities, and any progress will be volatile. Whilst most commentators have the same opinion with the fact that structural transformation needs to happen, the debate on how best to achieve it and to ensure that it benefits the poorest is long-standing. There is very mixed proof for example that the conventional prescriptions of trade openness and investment liberalization achieve transformation or raise the incomes of poor households ,and there are a significant number of examples where these have disadvantaged poorer countries10. Social protection

Social protection is also a well-known policy area in the inclusive growth literature. Whilst also being a tool for promoting greater equality and poverty drop through direct transfers and redistribution, it also has a more dynamic role to play in achieving inclusive growth. In Brazil transfers to poor households, notably through the Bolsa Familia conditional cash transfer scheme, are credited with one third of the fall in inequality in the early 2000s of that country. This stimulated aggregate demand and consumption, creating a virtuous cycle of increased purchasing power – increased demand – higher labor demand – higher income.

Conclusions

Inclusive growth is a different concept from standard economic growth and is accompanied by a exclusive set of policy recommendations. It is often, however, included in donor approaches without much clarity about how an inclusive approach differs from the standard approaches. In mitigating against this risk, it is significant that we work towards a definition of inclusive growth and look at the important factors that would contribute towards growth being more inclusive. To this end, in this paper we have tried to discover the key elements of inclusive growth as a step towards a working definition of this concept. We have then considered in some detail the various significant aspects for making growth more inclusive.

References

1. ADB (2012) . ADB, Manila . 2. Acemoglu& Robinson (2012) . Profile Books,

London

3. Bass, Raworth, &Wykes (2014) . CAFOD & IIED, London. http://bit.ly/1q8j6Og

4. Berg &Ostry (2011) IMF Staff Discussion

Note, International Monetary Fund, Washington DC.

5. Cervantes-Godoy &Dewbre (2010) OECD

Food and Fisheries Working Paper 23, OECD, Paris

6. Chandy, Ledlie&Penciakova (2013). Brookings Institute, Washington DC

7. International Monetary Fund (2013) Statement

by the Managing Director on the Work

Program of the Executive Board Executive

Board Meeting. November 25, 2013. http://bit.ly/1lCzzIo

8. International Monetary Fund (2014) .IMF Staff

Discussion Paper by J. Ostry, A. Berg, and C. Tsangarides. February 2014. http://bit.ly/1dzoFjl

9. World Bank (2013c): The Foundation for

Shared Prosperity”. World Bank, Washington DC

10. World Bank (2013d) “The World Bank Group

Goals: End Extreme Poverty and Promote

Shared Prosperity”. World Bank, Washington DC

Baitharu T R & Pani S K: The Role of Big Data in Inclusive Growth: An Overview

http://bit.ly/1dzoFjl


Performance Analysis of three sided Artificially Roughened Solar Air Heaters

Ashwini Kumar1*, Ravi Kumar

1 & Arun Kumar Behura

2

1Research Scholar, National Institute of Technology, Jamshedpur

2Department of Mechanical Engineering Poornima College of Engineering, Jaipur, India



Abstract Provision of artificial roughness on the absorber plate enhances heat transfer rate in solar air heaters, which also results in higher value of friction factor and more pumping power required. Artificially roughened solar air heaters have been analyzed1 and investigated2 for fully developed turbulent flow and have been found to have a better performance, both quantitatively and qualitatively as compared to those of the solar air heaters having smooth solar air heater under the similar operating conditions. A novel solar air heater with three sides artificially roughened has been analyzed3, which result in more increase in heat transfer and friction factor than those of one side artificially roughened solar air heater. Thermal performance of three sides artificially roughened solar air heater has been analyzed4, whereas, one side artificially roughened solar air heater has been optimized5 and investigated6 for the maximum heat transfer, friction factor and the minimum pumping power. This paper represents an investigation for the various performance characteristics of three sides artificially roughened solar air heaters with three sides glass covers under actual outdoor conditions and compare well with smooth ones, also having three sides glass covers. Keywords Heat transfer coefficient, Thermo hydraulic performance, Heat transfer enhancement factor, Friction enhancement factor.

Artificial roughness is a well-known method to increase the heat transfer by use of regular geometric roughness elements on the surfaces. Fully developed turbulent flow heat transfer and friction factor for artificially roughened ducts, annuli and tubes have been widely studied7-10. A number of solar air heaters have been designed and developed over the years to refine their thermal enhancement. The thermal efficiency of solar air heaters is usually low due to low value of heat transfer coefficient between absorber plate and flowing air, which raises the absorber plate temperature, leading to higher heat losses. Heat transfer enhancement for fully developed turbulent flow in a solar air heater duct with small diameter wires on the absorber plate were analysed1. Continuous ribs at an inclination of 600 to the air flow direction have been used11. Chamfered rib roughness on the absorber plate was used12 and found that at low flow rate, higher

relative roughness height yields a better performance. Transverse ribs have been used13 to enhance heat transfer coefficient. Wire mesh roughness14 transverse protrusion wire roughness6, wedge shape ribs15, V-shape ribs16, arc shape roughness17, dimple shape roughness18, combined inclined and transverse ribs19, multi V-rib roughness20, w-shaped ribs21 are the works on analysis and investigations, where appreciable enhancement in heat transfer coefficient has been found quantitatively and qualitatively both. The enhancement of heat transfer coefficient attempted by providing artificially roughness, always results in an increment of pressure drop and the requirement of pumping power is increased. However, it results in higher value of thermal performance. Based on the analysis4 the experiments have been conducted for three sides artificially roughened solar air heaters under the actual outdoor conditions at varying values of roughness and flow parameters for an investigation for the various performance characteristics of three sides artificially roughened solar air heaters with three sides glass covers under actual outdoor conditions and compare well with smooth ones, also having three sides glass covers.

Corresponding Author: Ashwini Kumar e-mail: [email protected]

ISSN: 2394-3173 (Print)

2395-3225 (Online)

113

Experimental Procedure

The experimental set-up consists of two rectangular solar air heater ducts of similar size, three sides roughened and the smooth one. The experimental set-up for investigation consists of the two similar size rectangular solar air heater ducts of high aspect ratio (W>>B) as shown in Fig. 1. Both the ducts are having three sides glass covers. The total length of the ducts consists of bell-mounted entry sections for flow stabilization and test sections. Mass flow rate was varied by controlling the blower speed by means of a 3-phase auto variac. Flange-tape orifice-meters measured the flow rates in both the solar air heaters (roughened and smooth).

Fig. 1 Shematic of experimental set-up Since both the solar air heater ducts are similar in dimensions and are connected to a single blower to run simultaneously, mass flow rate for a particular run for both the solar air heaters measured by means of two separate flange tape orifice-meters happened to be the same. Intensity of solar radiation was measured by a pyranometer.


A wide range of experimental data for roughened absorber plates were collected simultaneously with the smooth ones. Table 1 shows the range of roughness and flow parameters investigated. The experimental data with respect to the relative roughness height, relative roughness pitch, flow Reynolds number, intensity of solar radiation, plate and air temperatures, pressure drops along the duct length and orifice-meter have been reduced to obtain the results, using the relevant expressions. The experimental values of heat transfer coefficient have been obtained using the following Eq. (1): ( ) ( ) (1)

which have been further used to find out the values of Nusselt number for smooth and roughened collectors by using the following equation:

(2)

Table 1 Range of parameters investigated

Sl. No

Parameters Range of parameters

1 Mass flow rate (Kg/s) 8.36 × 10-3 – 3.74 × 10-2

2 Reynolds number, Re 4000 – 20000 3 Roughness height 0.6 mm – 1.1

mm 4 Roughness pitch 6 mm – 30 mm 5 Relative roughness

pitch, p/e 10 – 30

6 Relative roughness height, e/D

0.0135 – 0.0247

Fig. 2 & 3 show the effect of the roughness parameters p/e and e/D respectively, on Nusselt number in three sides roughened collectors. The Nusselt number in those of the smooth ones at the same values of flow Reynolds number are also shown in these figures. Fig. 2 shows the effect of p/e on heat transfer for a given value of e/D, equal to 0.0247. It is clear from this figure that the values of Nusselt number increase with the decrease in the values of the relative roughness pitch p/e, and also the values of Nusselt number increase with increasing values of the flow Reynolds number, Re, but at a faster rate than that in the smooth collector. At a flow Reynolds number of 9806, the values of Nusselt number are about 58, 62 and 66 in three sides roughened collector for p/e equal to 20, 15 and 10, whereas, it is 32 in the smooth collector. Fig. 3 shows the effect of e/D on heat transfer for a given value of p/e, equal to 10. It could be seen from this figure that the values of Nusselt number increase with the increasing value of e/D, with increasing values of flow Reynolds number, also at a faster rate than that in smooth ones. At a flow Reynolds number of 9806, the values of Nusselt number in three sides roughened collector are about 56, 61and 64 for the respective values of e/D, equal to 0.0135, 0.0225 and 0.0247 at a given value of p/e, equal to 10, whereas, it is 30 in the case of smooth collector.

Kumar A, Kumar R & Behura A K: Performance analysis of three sided artificially roughened solar air heaters

114

2000 4000 6000 8000 10000 12000

20

30

40

50

60

70

80 p/e=10

p/e=15

p/e=20

smooth

e/D= 0.0247

Re

ruN

SNu

Fig. 2 Effect of p/e on heat transfer in three sides

artificially roughened solar air heater

2000 4000 6000 8000 10000 12000

10

20

30

40

50

60

70

80

e/D=0.0247

e/D=0.0225

e/D=0.0135

smooth

Re

ruN

SNu

p/e=10

Fig. 3 Effect of e/D on heat transfer in three sides


Fig. 4 &5 represent results w.r.t. friction factor for three sides roughened and the smooth one for given value of e/D and p/e, respectively. The values of has been taken from Moody chart to work out for values of by using Eq. (3) of Prasad et al (2015), written under as:

( )

[

{ ( )

( ) }

]

( ) (3)

Fig. 4 shows the effect of p/e on friction factor for a given value of e/D, equal to 0.0247. It could be seen from the figure that the values of friction factor increase with decrease in the value of the relative roughness pitch p/e, decrease with increasing values of the flow Reynolds number, Re for three sides roughened collector and the smooth ones.

2000 4000 6000 8000 10000 12000

0.024

0.028

0.032

0.036

0.040

0.044

Re

p/e=10

p/e=15

p/e=20

smooth

e/D=0.0247

rf

Sf

Fig. 4 Effect of p/e on friction factor in three sides


2000 4000 6000 8000 10000 12000

0.020

0.024

0.028

0.032

0.036

0.040

0.044

Re

e/D=0.0247

e/D=0.0225

e/D=0.0135

smooth

p/e=10

rf

Sf

Fig. 5 Effect of e/D on friction factor in three sides


Similarly, Fig. 5 shows the effect of e/D on friction factor for a given value of p/e, equal to 10. It is quite clear from the figure that the values of friction factor increase with the increase in the value of relative roughness height, e/D and the values of friction factor decrease with increasing values of flow Reynolds number, Re for three sides artificially roughened collector and the smooth ones. Inclusion of artificial roughness invariably increases friction factor, leading to more pumping power. The rate of heat transfer enhancement due to inclusion of artificial roughness and that of friction factor have not been found to be the same. The heat transfer enhancement factor, and friction enhancement factor, , defined by Eqs. 4 and 5 respectively have been considered to represent the thermo hydraulic results as shown in Fig. 5, for given value of e/D equal to 0.0247 and varying values of relative roughness pitch and flow Reynolds number. Fig. 5 shows the results of heat transfer enhancement factor, , and friction


115

enhancement factor, , with increasing values of Reynolds number for a given value of e/D, equal to 0.0247 at different values of p/e.

(4)

(5)

2000 4000 6000 8000 10000 12000

0.38

0.40

0.42

0.44

0.46

0.48

0.50

Re

p/e=10(NuF)

p/e=10(fF)

p/e=15(NuF)

p/e=15(fF)

p/e=20(NuF)

p/e=20(fF)

FNu

Ff

e/D=0.0247

Fig. 6 Heat transfer enhancement factor and friction

loss factor

It could be seen from this figure that the values of both heat transfer enhancement factor and friction enhancement factor increase with the increasing values of Reynolds number. Fig. 6 also shows that for a given value of e/D the rate of increment of is higher than that of at varying values of p/e. In the range of the parameters investigated, the value of heat transfer enhancement factor is in the range of 0.378 to 0.487, whereas, it is in the range of 0.384 to 0.491 for that of friction factor. It could be attributed from Fig. 6 that the rate of increase of the enhancement factor is more for the lower value of Reynolds number. At higher values of Reynolds number, the rate of increase of heat transfer enhancement factor appears to be monotonous. It can therefore, be concluded that performance of such solar air heater could be better at lower values of Reynolds number. In Fig. 2 to 5, slopes of the curves for and in thecase of three sides’ roughened collectors show more increase in heat transfer increasing values of Reynolds number at varying values of e/D and p/e, as compared to that of the smooth ones. Conclusions

Three sides artificially roughened solar air heaters have enhanced rate of heat transfer with the increasing values of flow Reynolds number and relative roughness height for a given value of relative roughness pitch and relative roughness

pitch for a given value of relative roughness height as compared to the smooth ones under the same operating conditions of mass flow rate. The values of heat transfer coefficient parameter, Nusselt number have been found to be in the range of 31.24 to 75.62 and heat transfer enhancement factor have been found to lie in between 0.378 to 0.487, for the range of parameters investigated.

Nomenclature

collector area, m2

B solar air heater duct height, m Cp specific heat of air at constant pressure, J/kg K D hydraulic diameter of solar air heater duct, m

e roughness height, m

e+ roughness Reynolds number, ⁄ √

e/D relative roughness height f friction factor fS friction factor for smooth duct fr friction factor for four sided rough duct average friction factor friction enhancement factor h convective heat transfer coefficient k thermal conductivity of air, W/m K L collector length, m mass flow rate of air, kg/s Nusselt number average Nusselt number Nusselt number for smooth duct Heat transfer enhancement factor, p pitch of roughness element, m p/e relative roughness pitch Pr Prandtl number Re flow Reynolds number T0 outlet temperature of air, 0C Ti inlet temperature of air, 0C average plate temperature, 0C average air temperature, 0C W width of solar air heater duct, m

References

1. Prasad B N & Saini J S, Sol. Energy, 41 (1988) 555.

2. Prasad B N, Sol. Energy, 91, (2013) 59. 3. Prasad B N, Behura A K & Prasad L, Sol.

Energy, 105 (2014)27. 4. Prasad B N, Kumar A & Singh K D P, Sol.

Energy, 111 (2015)313. 5. Prasad B N & Saini J S, Sol. Energy, 47

(1991)91. 6. Verma S K & Prasad B N, Renew Energy, 20

(2000)19.

Kumar A, Kumar R & Behura A K: Performance analysis of three sided artificially roughened solar air heaters

116

7. Webb R L, Eckert E R G & Goldstein R J, Int.

Journal of Heat Mass Transfer, 14 (1971)601. 8. Han J C, Trans. ASME J. of Heat Transfer, 106

(1984)774. 9. Sheriff N & Gumley P, Int. Journal of Heat

Mass Transfer, 9(1966) 1297. 10. Dalle Donne M & Meyer L, Int. Journal of Heat

Mass Transfer, 20 (1977)583. 11. Gupta D, Solanki S C, Saini J S, Sol. Energy 61

(1997)33. 12. Karwa R, Solanki S C & Saini J S, Int. Journal

of Heat Mass Transfer, 42 (1999)1597. 13. Gupta D, Solanki S C & Saini J S, Solar energy

51 (1993)31. 14. Saini R P & Saini J S, Int. journal of Heat mass

transfer, 40 (1997) 973.

15. Bhagoria J S, Saini J S & Solanki S C, Renewable Energy, 25, (2002)341.

16. Momin A M E, Saini J S, Solanki S C, Int. J

Heat Mass Transfer, 45 (2002)3383. 17. Saini S K & Saini R P, Sol. Energy, 82

(2008)1118. 18. Saini R P & Verma J, Energy, 33 (2008)1277. 19. Varun, Saini R P & Singal S K, Renewable

Energy, 33 (2008)1398. 20. Hans V S, Saini R P & Saini J S, Sol. Energy,

84(2010)898. 21. Lanjewar A M, Bhagoria J L & Sarviya R M,

Journal of Experimental Thermal and Fluid

Science, 35 (2011)986.



The Effect of Roughness and Flow Parameters for Heat Transfer Enhancement

in Artificially Roughened Solar Air Heaters: - A Review

1Ravi Kumar,

2Arun Kumar Behura,

1Ashwini Kumar,

3Salila Ranjan Dixit

1 Research Scholar, National Institute of Technology, Jamshedpur

2Department of Mechanical Engineering Poornima College of Engineering, Jaipur, India

3 Orissa Engineering College, Bhubaneswar



Abstract Provision of artificial roughness is made to enhance heat transfer rate in solar air heaters. Information regarding different configurations and geometries of roughness elements producing different quality and quantity of heat transfer is available in literature. This paper reviews the comparative rate of heat transfer quantitatively and qualitatively in artificially roughened solar air heaters of various configurations. Analytical and experimental result as well as worked out values of result with respect to heat transfer data (Average Nusselt number), utilizing the equation/correlations developed by various authors have been represented with respect to the roughness and flow parameters (p/e, e/D and Re), for comparison in rate of heat transfer. The experimental values of average Nusselt number in the case of multi V-roughness has been found to be the highest. However, the analytical values of average Nusselt number in the end of side roughened solar air heaters are the maximum. Keywords Relative roughness pitch (p/e), Relative roughness height (e/D), Flow Reynolds number (Re), Average Nusselt number ( ).

Now a days solar air heaters find their use to produce heated air at low to moderate temperature for several industrial and domestic purposes. As it is well known that the thermal efficiency is very low due to low convective heat transfer coefficient between the absorber plate and air, leading to high absorber plate temperature and massive amount of heat losses to the ambient. Thus to enhance the heat transfer, roughness on absorber plate were introduced. In this paper the literature shows the use of artificial roughness of different geometries to enhance heat transfer in solar air heaters is widely available. 1The analysis with respect to fluid flow and heat transfer in a novel solar air heater having artificial roughness on three sides (the two side walls and the top side) of the rectangular solar air heater duct, with three sides glass covers. Equations for friction factor and heat transfer parameter have been developed.

The analytical values of friction factor and heat transfer parameter have been found to be 2 to 40% more and 20 to 75% more than those of the respective values of2 for the same range of the values of operating parameters p/e, e/D and Re and fixed values of W and B. 3The small diameter wires on the top absorber plate were placed to provide roughness for fluid flow in duct to enhance the heat transfer in a solar air heater used. The effect of protrusions on absorber surface in the form of small diameter wires on heat transfer and friction factor for fully developed turbulent flow in a solar air heater duct was analyzed2. Investigations were carried out4 for the relative roughness pitch of 10, 15 and 20 and relative roughness height of 0.020, 0.027 and 0.033 to see the effect of height and pitch of the roughness elements on heat transfer and friction. Where, the maximum value of Nusselt number and friction factor were reported to be 2.38 and 4.25 respectively, for relative roughness pitch of 10.5The optimal thermo hydraulic performance of top side artificially roughened solar air heaters were analysed, covering a wide range of the values of relative roughness pitch (p/e), relative roughness height (e/D) and flow Reynolds

Corresponding Author: Ravi Kumar e-mail: [email protected]

ISSN: 2394-3173 (Print)

2395-3225 (Online)

118

number (Re), to arrive at the conclusion that the value of the parameter, roughness Reynolds number, e+ 24 gives the optimal value of thermo hydraulic performance. 6The effect of transverse and inclined wire roughness on fluid flow characteristics for solar air heater are examined. 7The heat transfer and friction characteristics for flow inside a solar air heater duct of large aspect ratio with roughness in the form of expanded metal mesh geometry. 8Heat transfer coefficient and friction factor correlations were developed for rib-roughened solar air heater duct for transitional flow. 9The optimal thermohydraulic performance experimentally verified for artificially roughened solar air heaters and concluded that the value of flow Reynolds number, e+ 24, gives the optimal thermohydraulic performance. 10Wedge shaped transverse repeated rib roughness used on one broad heated wall of solar air heater duct and generated data pertinent to friction and heat transfer. 11The performance of solar air heater duct roughened with arc shape roughness elements were explored. Experimentations were conducted to predict the effect of various roughness parameters such as relative roughness height, relative arc angle on heat transfer coefficient for the range of Reynolds number (Re), from 2000 and 17000, relative roughness height (e/D), 0.0213 to 0.0422 and relative arc angle (α/90), 0.3333 to 0.6666. 12Experimentally used a combination of transverse and inclined ribs

as roughness geometry and examined the thermal performance for the range of Reynolds number (Re), 2000-14000, pitch of ribs (p), 5-13 mm, roughness height (e), 1.6mm and aspect ratio (W/H), of 10. Table 1 represents various roughness geometries used in solar air heaters and their relevant correlations.13Flow through duct roughened with V-shape ribs attached to the underside of one broad wall of the duct, to collect data on heat transfer and fluid flow characteristics were investigated experimentally.14Reviewed on roughness geometries used in solar air heaters, 15Reviewed on performance of artificially roughened solar air heaters. 16Multiple V-rib roughness and performed extensive experimentation developed to collect data on heat transfer and fluid flow characteristics of a roughened duct. 17The author analysed that small diameter protrusion wires are better in the flow Reynolds number limited to 10000. 18Author predicted for effective efficiency of solar air heater using discrete type of ribs.19The types of roughness geometries and investigation techniques used in artificially roughened solar air heaters reviewed.20Regarding approach for further research reviewed on use of turbulence promoters for heat transfer enhancement in solar air heaters, as also the performance of double pass solar air heaters. 21The thermal and thermo hydraulic performance of protruded solar air heater developed.

Table 1 Representation of various roughness geometries used in solar air heaters

Sl.

No.

Reference Roughness Geometry Parameter

Investigated

Associated Equations / Correlations

1 Gupta et al., (1993)

Inclined ribs

e/D=0.020-0.053 p/e=7.5 & 10 =30-90 Re=5000-30000

( ⁄ )

( ⁄ )

0 ( ⁄ )

1

For ( ⁄ )

( ⁄ )

0 ( ⁄ )

1

For

( ⁄ )

( ⁄ )

( )

2

Saini and Saini (1997)

Wire mesh roughness

e/D=0.012-0.039 S/e=15.62-46.87 L/e=25.00-71.87 Re=1900-13000

( ⁄ )

( ⁄ )

0 { ( ⁄ )} 1. ⁄ /

[ { ( ⁄ )}

]

( ) ( ⁄ )

. ⁄ /


119 Kumar R, Behura A K, Kumar A & Dixit S R : The effect of roughness and flow parameters for heat transfer enhancement in artificially roughened solar air heaters: - A review

3 Prasad and

Saini (1988)

Small diameter protrusion wire

e/D=0.020-0.033 p/e=10-20 Re=5000-50000

⁄

√

0 ( ) (

⁄ )

1

( ) [

{ (

⁄ )

( ⁄ ) } ]

( )

4 Prasad et al., (2014)

Small diameter protrusion wire in three sides p e Fluid Flow W L Top wall p e Fluid B FlowL Side wall

e/D=0.020-0.033 p/e=10-20 Re=3000-12000

4√ 5 [ ( ) (

⁄ ) ]

( ) [

{ (

⁄ )

( ⁄ ) } ]

( )

5 Bhagoria et al., (2002)

Wedge shape ribs

e/D=0.015-0.033

=8,10,12,15 Re=3000-8000

( ⁄ )

(

⁄ )

[ { (

⁄ )}

](

⁄ )

[ 2 .

⁄ /3

]

( ⁄ )

(

⁄ )

(

⁄ )

6 Momin et

al., (2002) V-shape ribs

e/D=0.02-0.034 p/e=10 α=30-90 Re=2000-15500

( ⁄ )

( ⁄ )

0 { ( ⁄ )} 1

( ⁄ )

( ⁄ )

, (

⁄

) -

7 Saini and Saini (2008)

Arc shape roughness

e/D=0.0213-0.0422 p/e=10 Re=2000-17000 α/90=0.333-0.666 W/H=12

( ⁄ )

( ⁄ )

( ⁄ )

( ⁄ )

8 Varun et al., (2008)

Combined inclined and transverse ribs

e/D=0.030 p/e=8 W/H=10 Re=2000-14000

( ) (

⁄ ) ( ) (

⁄ )

120

9 Hans et al., (2010)

Multi V-rib roughness

e/D=0.019-0.043 p/e=6-12 Re=2000-20000 α=30-75 W/w=1-10

( ⁄ )

( ⁄ )

( ⁄ )

0 { ( ⁄ )} 1 0 { ( ⁄ )}

1(

⁄ )

[ { (

⁄ )}

]

( ⁄ )

( ⁄ )

( ⁄ )

[ . .

//

] (

⁄ )

0 ( (

⁄ )) 1

10 Prasad (2013)

Transverse rib roughness

e/D=0.0092-0.0279 p/e=10-40 Re=2959-12631

(

⁄ )

[

√(

⁄ ) 2 ( )

(

⁄ )

3]

, (

⁄ )

( ⁄ ) -

11 Saini et al., (2008)

Dimple shape roughness

e/D=0.0189-0.038 p/e=8-12 Re=2000-12000

(

⁄ )

0 ( ){ (

⁄ )} 1 ( ⁄ )

0 ( ){ ( ⁄ )} 1

( ) ( ⁄ )

(

⁄ )

0 {

⁄ }

1

[ * ⁄ + ]


121 Kumar R, Behura A K, Kumar A & Dixit S R : The effect of roughness and flow parameters for heat transfer enhancement in artificially roughened solar air heaters: - A review

2000 4000 6000 8000 10000 12000 14000

0

20

40

60

80

100

120

140

Re

(1) Prasad et al., (2014)

(2) Saini & Saini, (1997)

(3) Bhagoria et al., (2002)

(4) Prasad & Saini (1988)

(5) Gupta et al., (1993)

(1)

(2)

(3)

(4)

(5)

Nu

e/D=0.032

p/e=10

Fig. 1 Comparison of average values of Nusselt number

0.000005

0.000010

0.000015

0.000020

Re

(1) Prasad & Saini, (1988)(2) Prasad et al., (2014)(3) Bhagoria et al., (2002)(4) Gupta et al., (1993)

2000 4000 6000 8000 10000 12000 14000

(1)

(2)

(3)

(4)

e/D=0.032

p/e=10

rff ,

Fig. 2 Comparison of average values of friction

factor

2000 4000 6000 8000 10000 12000 14000

0

20

40

60

80

100

120

140

160

180

200

Re

(1) Han et al., (2010)(2) Momini et al., (2002)(3) Saini & Saini, (2008)(4) Saini et al., (2008)(5) Varun et al., (2008)

(1)

(2)(3)

(4)

(5)

Nu

e/D= 0.0315

p/e=10

Fig. 3 Comparison of experimental values of

average Nusselt number


Studies of artificially roughened solar air heater duct predominantly concerned with the effect of shape and arrangement of roughness elements on heat transfer requirement comparative assessment. It is therefore, reasonable to compare the performance of some distinct roughness geometries separately with respect to heat transfer. Fig. 1&2 have been drawn as such, with the help of worked out values of the heat transfer data, and respectively by substituting the values of roughness and flow parameters in the equations developed by the respective authors and the variation in average Nusselt number and average friction factor as a function of Reynolds number for different roughness geometries, analytically developed by different investigators. Considerable increase in Nusselt number and friction factor can be seen in all the cases. Fig. 1 reveals that the value of Nusselt number is highest in case of transverse rib in three sided (the two side walls and the top side) artificially roughened solar air heater duct and lowest in case of inclined ribs for all the values of Reynolds number. Transverse rib roughness in three sides shows discrete performance among all the roughness geometries and provides almost double increment in heat transfer rates in comparison to other roughness geometries. Fig. 3 has been drawn for the respective experimented values of heat transfer data, and the variation of average Nusselt number as a function of Reynolds number for roughness geometries tested experimentally by different authors. It can be seen that the value of Nusselt number is highest in case of multi V shape roughness and lowest in case of combination of transverse and inclined ribs for all the values of Reynolds number. Multi V shape roughness shows the maximum value of Nusselt number as compared to other roughness geometries. It can be seen that in case of V shape rib, multi V shape rib, inclined rib and transverse rib roughness, a step rise in Nusselt number and after that the increment rate of Nusselt number slightly diminishes. On the basis of this observation one can choose preferably wire mesh roughness or arc shape roughness for systems working at higher flow rate to achieve higher rate of heat transfer. But the system with low and moderate flow rates, multi V shape roughness is the best option as far as heat transfer enhancement is concerned. Therefore the geometries like V shape rib and multi V shape rib with gap at suitable location

122

could exhibit considerable enhancement in heat transfer rate as compared to continuous V or multi V ribs. It is believed that the secondary flow cells are responsible for higher heat transfer rates. Since inclined rib has only one secondary flow cell while V rib got two secondary flow cells and multi V rib roughness can generate multiple secondary flow cells and therefore multi V rib roughness shows maximum heat transfer augmentation.

Conclusions

Use of artificial roughened surfaces with different type of roughness geometries is found to be the most effective technique to enhance the heat transfer rates from the heated surface to flowing fluid at the cost of moderate rise in fluid friction. Multi V rib roughness is one of the most suitable form of roughness tested experimentally showed distinct performance in case of solar air heaters. In case of solar air heaters artificial roughness in three sides of the absorber plate(top side and two side walls) is one of the best form of roughness geometry developed analytically shows the higher rate of heat transfer. Experimentations on rib roughened duct employing roughened plates are to be prepared by either fixation of wires or machining on metallic plates. Both techniques seem to be obsolete as they involve tedious fabrication steps which involve higher cost and increase time duration.

Nomenclature

collector area, m2 solar air heater duct height, m hydraulic diameter of solar air heater duct, m e artificial roughness height, m

1 roughness Reynolds number √(

)

roughness Reynolds number √(

)

relative roughness height plate efficiency factor heat removal factor average friction factor ( ) ,in

roughened collector friction factor in four sided smooth duct friction factor in four sided rough duct average friction factor in three sided rough

duct solar air heater duct height, m

convective heat transfer coefficient, W/m2 K collector length, m

⁄ relative long way length of mesh

average Nusselt number for roughened duct average Nusselt number for roughened duct Nusselt number for four sided smooth duct roughness pitch, m

relative roughness pitch

Pr Prandlt number Reynolds number average Stanton number for roughened duct Stanton number for top side roughened duct Stanton number in a four sided rough duct s/e relative short way length of mesh solar air heater duct width, m width of single V-rib W/w relative roughness width W/H aspect ratio of duct UL overall heat transfer coefficient, W/m2 K fluid density, Kg/m3

angle of attack (o) chamfer/ wedge angle (o)

thermal efficiency References

1. Prasad B N, Behura A K & Prasad L, Sol.

Energy, 105 (2014)27. 2. Prasad B N, Saini J S, Sol. Energy, 41

(1988)555. 3. Prasad K, Mullick SC, Applied Energy,

13(1983) 83. 4. Prasad B N, Sol. Energy, 91(2013)59. 5. Prasad B N & Saini J S, Sol. Energy, 47(1991)

91 6. Gupta D, Solanki S C & Saini J S, Solar

energy, 51(1993)31. 7. Saini R P & Saini J S, Int. journal of Heat mass

transfer, 40(1997)973. 8. Karwa R, Solanki S C & Saini J S, Int. Journal

of Heat Mass Transfer, 42(1999)1597. 9. Verma S K & Prasad B N, Renew Energy,

20(2000)19. 10.Bhagoria, J S, Saini J S & Solanki S C,

Renewable Energy, 25(2002)341 11.Saini S K & Saini R P, Sol. Energy, 82(2008)

1118. 12.Varun, Saini R P & Singal S K, Renewable

Energy, 33(2008)1398. 13.Momin A M E, Saini J S & Solanki S C, Int. J

Heat Mass Transfer, 45(2002)3383. 14.Varun, Saini R P & Singal S K, Sol. Energy,

81(2007) 1340. 15.Hans V S, Saini R P & Saini J S, Renewable

and Sustainable Energy Reviews,13 (2009)1854.

16.Hans V S, Saini R P & Saini J S, Sol. Energy, 84(2010)898.


123Kumar R, Behura A K, Kumar A & Dixit S R : The effect of roughness and flow parameters for heat transfer enhancement in artificially roughened solar air heaters: - A review

17.Sharma M &Varun, Int. Journal of Energy and

Environment, 1(5)(2010)897. 18. Sethi M, Sharma M, Varun, Int. Journal of

Energy and Environment, 1(2)(2010)333. 19. Patil A K, Saini J S & Kumar K, Int. Journal

of Renewable Energy Research, 2(2012)1.

20. Chamoli S, Chauhan R, Thakur N S & Saini J S, Int. Journal of Renewable and Sustainable

Energy Reviews, 16 (10)(2012)481. 21. Bhushan B & Singh R, Int. Journal of Solar

Energy, 86 (11)(2012)3388.


Design, Synthesis and Fluorescence Study of 2-Phenyl-3-Nitro Chromene

Derivatives for H2S Detection

Sabita Nayak*

Department of Chemistry, Ravenshaw University, Cuttack – 753 003, Odisha

Received 15 March 2016; accepted 15 April 2016

Abstract Fluoregenic α,β unsaturated nitro compounds are used as fluorescent probe for H2S detection in biological system. Here with 2-Phenyl-3-nitro-chromene derivatives were synthesized and its fluoregenic properties were studied with an expectation to use further as new fluorescent probe for H2S. Two nitrochromene named as 7-methoxy-3-nitro-2-phenyl-2H-chromene and 2-(4-methoxyphenyl)-3-nitro-2H-chromen-6-ol were synthesized following Michael aldol reaction of substituted salicylaldehyde and β-nitrostyrene using DABCO in neat condition heating at 40 oC with good yield. Synthesized compounds were well characterised by 1H, 13C NMR and MP study. Absorbance and emittance of the compounds were studied in various solvents to understand the solvatochromic effect. Both the compounds show good fluorescence in polar solvents. Keywords Nitro chromene, Oxamichael addition reaction, Nitrostyrene, Fluorescence Intracellular reactive sulfur species (RSS) is a general term for sulfur-containing biomolecules. These molecules play critical roles in physiological and pathological processes. Glutathione (GSH), the most abundant intracellular nonprotein thiol, can control intracellular redox activity, intracellular signal transduction, and gene regulation. Cysteine (Cys) is implicated in slow growth in children, liver damage, skin lesions, and loss of muscle and fat. Homocysteine (Hcy) is a risk factor for Alzheimer’s disease and cobalamin (vitamin B12) deficiency. H2S has been identified as the third gasotransmitter following nitric oxide (NO) and carbon monoxide (CO). At physiological levels, H2S regulates the intracellular redox status and fundamental signalling processes, including regulation of vascular tone, myocardial contractility, neurotransmission, and insulin secretion. Abnormal levels of H2S in cells can induce many diseases, such as Alzheimer’s disease, liver cirrhosis, gastric mucosal injury and arterial and pulmonary hypertension1,2. Therefore, development of accurate tools for its detection and measurement becomes important. Traditional methods for H2S detection

reported3-5. As a result of its high activity, volatility and flammability, and fast catabolism, a technique able to spatially and temporally monitor H2S is more attractive. However, these above methods can not meet the demand. Recently several elegant fluorescent imaging probes for H2S detection have come into place. They are developed by taking advantage of the strong reduction power, 6-

12nucleophilicity and binding affinity with metals of H2S. For all these probes, the desired ‘‘off–on’’ in fluorescent intensity was obtained. However, some of them have drawbacks. The probe based on nucleophilic substitution has the possible interference from thiol-containing amino acids, such as cysteine and homocysteine; the probes based on affinity with Cu2+ displayed excellent kinetics, but cell permeability and toxicity of Cu2+ were not negligible13-18. Although the probes based on H2S reductive property are highly selective, currently available probes based on azide-reduction exhibit limited sensitivity and/or require high concentration (100–200 mM). The H2S concentration in blood is 10–100 mM and in living cells it is in an even lower submicromolar range. Therefore, highly sensitive fluorescent probes are still in demand. Towards this end, we would like to report a new fluorescent probe for H2S which allows for the detection of H2S at submicromolar concentrations in cells with improved sensitivity.

Corresponding Author: Sabita Nayak e-mail: [email protected]

ISSN: 2394-3173 (Print)

2395-3225 (Online)

125

N OO

NHOH

N

S

N3

N OO

O

NO2

O OHO

COOH

HN

ON

NHNH

HN

Cu2+

N

NO2

N

HSip-1

Cy-NO2

HSN11 23 4

5

O O

N3

R

R = -OH

R= NEt2

O

N

N3

O ON3 O O

N3

O

NC CN

N3

6 7 8

910

Fig. 1 Fluorophore used for H2S detection in Biological system19

A commonly used strategy in the development of fluorescent sensors exhibiting changes in the emission profile is the manipulation of electronic features of substituents of a fluorophore through either intramolecular charge transfer (ICT) or photoinduced electron transfer (PET) pathways. The PET strategy has been successfully used in the design of PET based fluorescent sensors because of predictable efficiency of the PET process. Nevertheless, the ICT type of fluorescent probes is relatively few, but it can afford high sensitivity since it has a very low intrinsic fluorescence. Suitably substituted azide derivatives are reported for H2S detection. Very few Nitro derivatives are reported for H2S detection. Fluorophore used for H2S detection is shown in Fig. 1.

There exists a major obstacle in the design of fluorescent probes by exploiting nitro fluorophores, because the nitro group has always been considered to be a strong quencher of fluorophores. However, the nitro group can be reduced by Na2S to produce the corresponding amino group under mild conditions, which opens a door to the design and synthesis of new types of fluorescent probe containing a nitro group for H2S detection. Taking advantage of this reductive reaction, and nontoxic nature of Nitrochromene we synthesized two nitrochromene to study it’s potentiality for H2S detection.

OH

O

H

NO2

O

NO2

DABCO

40 oC, heatingR2R

R1

R2R

R1

R= H, OMe

R1 = H, OHR2 = H, OMe

11a-b 12 13 a-b

Yield= 80-82%

Scheme 1 Synthesis of Nitrochromene13a-b Literature studies reveals that DABCO catalyzed

reactions are reported for synthesis of nitro chromene following Oxa-Michael-Aldol reaction20 -

21. Reaction of substituted salicylaldehyde 11a-b with β-nitrostyrene 12 in DABCO neat condition heating at 40-60 oC provided nitrochromene in very good yield. The structure of the product 13a-b was confirmed by spectroscopic analysis.

After synthesizing compound 13a and 13b, we have studied the absorbance in CHCl3, MeOH and emittance of the synthesized compounds in various solvents such as Hexane, CHCl3, EtOAc, THF, Acetone, ethanol, methanol, DMF, MeCN, DMSO, 50% MeOH in H2O and 80% EtOH in H2O. Absorbance and emittance spectra of compound 13a

and 13b shown in Fig. 5 and 6.

Materials and Methods All reagents and solvents were purchased from commercial suppliers. Dry solvent was obtained according to the standard procedure. Column chromatographic purifications were performed using Sigma-Aldrich silica gel 100-200 mesh. Progress of the reaction was monitored by TLC on silica gel 60 F254-coated TLC plates (Merck KGaA, Darmstadt, Germany) and visualized by Short-UV light at 254 nm.

Instruments

The proton nuclear magnetic resonance (1H &13C NMR) spectra were recorded on a Bruker Avance 400 MHz NMR spectrometer. Chemical shifts (δ) are reported in parts per million (ppm), downfield from the internal standard (TMS, δ = 0.00 ppm) relative to residual CHCl3 (1H: δ = 7.26 ppm, 13C: δ = 77.00 ppm) as an internal reference. Coupling constants (J) are reported in Hertz (Hz). Peak multiplicity is indicated as follows: s-singlet, d-doublet, t-triplet, q-quartet, m-multiplet and dd-doublet of doublet. The samples were prepared by dissolving 5 mg of each form in 600 μl of CDCl3. Melting points were recorded on an electro thermal digital melting point apparatus measured on a Stuart SPM10 melting point instrument in our laboratory.

General experimental procedure

Substituted salicylaldehydes (1.0 mmol), DABCO (0.2 mmol) and trans--nitrostyrenes (1.0 mmol) were added sequentially to a reaction vessel and stirred in room temerpature then heating at 40 oC for 2-3 h. Reaction was monitored by TLC, after completion of reaction, the reaction mixture was diluted with ethylacetate and extracted with water. The organic layer was separated, dried over anhydrous Na2SO4 and evaporated under reduced pressure. The crude product crystallised by isopropanol without further purification to furnish a crystalline solid compound in 80 & 82% yield. Compounds were characterized through 1H NMR,

Nayak S: Design, Synthesis and Fluorescence Study of 2-Phenyl-3-Nitro Chromene Derivatives for H2S Detection

126

13C NMR, CHN Mass spectral data, melting point and UV–Vis absorption and fluorescence spectroscopic analysis.

O

NO2

MeO

7-methoxy-3-nitro-2-phenyl-2H-chromene (13a): Camel yellow solid; mp 141oC. 1H NMR (400 MHz, CDCl3) δ (ppm) 8.08 (s, 1H), 7.42–7.34 (m, 5H), 7.26 (d,J=8.0 Hz, 1H), 6.59–6.57(m, 2H), 6.43–6.42 (m, 1H), 3.81 (s, 3H). Anal. Calcd for C16H13NO4: C, 67.84; H, 4.63; N, 4.94; Found: C, 67.80; H, 4.59; N, 4.89.

O

NO2HO

OCH3 2-(4-methoxyphenyl)-3-nitro-2H-chromen-6-ol

(13b):Orange solid; mp 131oC. 1H NMR (400 MHz, CDCl3) δ (ppm) 8.07 (s, 1H), 7.32–7.28 (m, 2H), 7.01–6.98 (m, 1H), 6.95–6.91 (m, 2H), 6.86-6.83 (m, 2H), 6.59 (s, 1H), 5.44 (s, 1H), 3.78 (s, 3H). 13C NMR (100 MHz, CDCl3) δ (ppm) 160.7, 144.9, 141.6, 139.8, 129.1, 128.6, 128.4, 122.9, 121.7, 120.2, 118.1, 114.4, 74.6, 55.3. Anal.Calcd for C16H13NO5: C, 64.21; H, 4.38; N, 4.68; Found: C, 64.23; H, 4.41; N, 4.70.

Fig. 2 1H NMR spectra of 7-methoxy-3-nitro-2-phenyl-2H-chromene (13a)

Fig. 3 1H NMR spectra of 2-(4-methoxyphenyl)-3-nitro-2H-chromen-6-ol (13b)

Fig. 4 13C NMR of 2-(4-methoxyphenyl)-3-nitro-2H-chromen-6-ol (13b)

UV–Vis Absorption Spectra We have measured the UV−Vis absorption spectra of compound X and Y. The absorbance of compound X and Y were performed in MeOH (a polar protic solvent) and Chloroform (a less polar aprotic solvent) at 1 × 10−4 M concentration. The results are shown in Fig. 5 and 6.

Compound 13a shows absorbance in 412 nm in CHCl3 and in MeOH405 nm. Compound 13b shows absorbance in 348 nm in CHCl3 and in MeOH.

Fluorescence Spectra

Emittance of compound 13a and 13b was studied at 1 × 10−4 M concentration in twelve different solvents such as Hexane, Chloroform, Ethyl Acetate, Tetrahydrofuran, Acetone, Ethanol, Methanol, N, N-dimethylformamide, Acetonitrile, Dimethyl Sulfoxide, 50% Ethanol (Ethanol:Water 1:1), 80% Methanol (Methanol:Water 4:1). The results are shown in Fig. 7 and 8.Compound 13a

O

NO2

H3CO

O

NO2HO

OCH3

O

NO2HO

OCH3


127

shows good fluorescence in 50% EtOH and 13b shows good fluorescence in CH3CN.

Conclusions

We have synthesized two nitrochromene 13a and 13b and characterised by 1H, 13C, MP study. Fluoregenic properties of these compounds are studied and showing good fluorescence in polar solvents. In further we will study the potentiality of these compounds for H2S detection inside biological system.

Acknowledgement

SN thanks DST India (SR/FT/CS-139/2011), UGC New Delhi (47-276/2013) and CSIR New Delhi (02(0134)/13/EMR-II) for providing research grant.

References 1. Wang R, Chen L, Liu P, Zhang Q & Wang Y, Chem

Eur J, 18 (2012) 11343. 2. Paul B D & Snyder S H, Nat Rev Mol Cell Biol, 13

(2012) 499. 3. Tangerman A, J Chromatogr. B, 877 (2009) 3366. 4. Olson K R, Biochim Biophys, Acta Bioenerg, 1787

(2009) 856. 5. Gemerden H V, Tughan C S, Wit R D & Herbert R

A, FEMS Microbiol Ecol, 62 (1989) 87. 6. Fukuto J M & Collins M D, Curr Pharm Des, 13

(2007) 2952. 7. Kazemi F, Kiasat A &Sayyahi S, Phosphorus Sulfur,

179 (2004) 1813.

8. Scriven E F V & Turnbull K, Chem Rev, 88 (1988) 297.

9. Wu S, Fu Y, Yan R, Wu Y, Lei X & Ye X S, Tetrahedron, 66 (2010) 3433.

10. Lippert A R, New E J & Chang C J, J Am Chem Soc, 133 (2011) 10078.

11. Montoya L A & Pluth M D, Chem Commun, 48 (2012) 4767.

12. Wang R, Yu F, Chen L, Chen H, Wang L & Zhang W, Chem Commun, 48 (2012) 11757.

13. Sasakura K, Hanaoka K, Shibuya N, Mikami Y, Kimura Y, Komatsu T, Ueno T, Terai T, Kimura H & Nagano T, J Am Chem Soc, 133 (2011) 10629.

14. Hou F, Cheng J, Xi P, Chen F, Huang L, Xie G, Shi Y, Liu H,Bai D & Zeng Z, Dalton Trans, 41 (2012) 5799.

15. Qu X, Li C, Chen H, Mack J, Guo Z & Shen Z, Chem

Commun, 49 (2013) 7510. 16. Zhang D & Jin W, Spectrochim Acta Part A, 90

(2012) 35. 17. Wang J, Long L, Xie D & Zhan Y, J Lumin, 139

(2013) 40. 18. Ida T, Sawa T, Ihara H, Tsuchiya Y, Watanabe Y,

Kumagai Y, Suematsu M, Motohashi H, Fujii S, Matsunaga T, Yamamoto M, Ono K, Devarie-Baez N O, Xian M, Fukuto J M &Akaike T, Proc Nat Acad

Sci USA, 111 (2014) 7606. 19. Yu F, Hanab X & Chen L, Chem Commun, 50 (2014)

12234. 20. Mohapatra S, Bhakta S, Chakroborty S, Tripathy M

& Nayak S, Res Chem Intermed, 41(10)(2015) 7799. 21. Bhanja C, Jena S, Nayak S & Mohapatra S, Beilstein

J Org Chem, 8 (2012) 1668.

Nayak S: Design, Synthesis and Fluorescence Study of 2-Phenyl-3-Nitro Chromene Derivatives for H2S Detection

https://www.infona.pl/resource/bwmeta1.element.springer-000000011164/tab/jContent

https://www.infona.pl/resource/bwmeta1.element.springer-000000011164/tab/jContent/facet?field=%5EjournalYear&value=%5E_02015

Hiranya Kumar Centre for Research & Development

Orissa Engineering College

Navajyoti Vihar, Nijigarh Kurki, Harirajpur, Jatni, Khurda – 752050

Administrative Office:

36 A, Sahid Nagar, Bhubaneswar – 751 007, Odisha, India

Journal Subscription Form

Name of the Institution/Individual: ………………………………………………………………………

Address for Correspondence: ………………………………………………………………………

………………………………………………………………………

………………………………………………………………………

………………………………………………………………………

International Journal of Energy, Sustainability & Environmental Engineering (ISSN: 2394-3165)

Applied Science and Advanced Materials International (ISSN: 2394-3173)

Type of Subscription: Institutional Individual

Annual Biannual

Rate of Subscription for each journal:

Type of Subscription 1 Year 2 Years

Institutional 1600.00 ($ 300.00*) 3000.00 ($ 500.00*)

Individual 1000.00 ($ 250.00*) 2000.00 ($ 450.00*)

(*Inclusive of first class mail)

For inland outstation cheques, please add Rs 50.00 and for foreign cheques, please add $ 10.00

Payments in respect of subscriptions may be sent by cheque/bank draft, payable to OEC Project

Account No. 1, and to Hiranya Kumar Centre for Research and Development, Orissa Engineering

College, 36 A sahid Nagar, Bhubaneswar 751 007. Bank charges shall be borne by subscriber.

Cheque/Bank Draft Details:

Name of the Bank Cheque/Draft Number Date Amount

Place: Signature with seal

Date:

Applied Science and Advanced Materials International

ISSN: 2394 – 3173 (Print); 2395 – 3225 (Online)


Author Index

Baitharu, T R 109

Behera , A K 85

Behura , A K 96, 112, 117

Dash, M 101

Dixit, S R 117

Haldar , R 90

Jagtap , S B 81

Kapoor, K 90

Kulkarn i, S S 81

Kumar , A 96, 112, 117

Kumar , R 96, 112, 117

Mishra , S 96

Mohant y, K 101

Mohant y, M 101

Nayak , S 124

Pani, S K 109

Patil , V D 81

Pradha n, G 101

Pramanik, N K 90

Samal, B P 106

Shukla, P G 81

Applied Science and Advanced Materials International

ISSN: 2394 – 3173 (Print); 2395 – 3225 (Online)


Keyword Index

ABS 90 Average Nusselt number 96, 117

Big data 109 Bio-composite 85

Cepstral coefficient 101 Cross linking 90

DEET 81 Double wall 81

eBay 109 e-beam irradiation 90 Erosion wear 106

Face book 109 Feature extraction 101 Flow Reynolds number (Re) 96, 117 Fluorescence 124 Friction enhancement factor 112

Heat transfer coefficient 112 Heat transfer enhancement factor 112

Inclusive growth 109

LinkedIn 109

Mechanical Testing 85 Metal matrix composites 106 Microencapsulation 81

Nanoclay 85 Nitro chromene 124 Nitrostyrene 124 nylon 6,6 90

Oxamichael addition reaction 124

Performance evaluation 101

Relative roughness height (e/D) 96, 117 Relative roughness pitch (p/e) 96, 117 Release study 81

Soy pulp 85 Speaker ID matching 101 Speech analysis 101

Taguchi method 106 TAIC 90 Thermo hydraulic performance 112 Thermoplastic Starch 85

Water absorption 90

Vol. 2 Issue 4 6 March - August 2016oec.ac.in/journals/ASAMI_V2_I46.pdf · Applied Science and...

Documents

Transcript of Vol. 2 Issue 4 6 March - August 2016oec.ac.in/journals/ASAMI_V2_I46.pdf · Applied Science and...