o l . 8, Is s u E 2, Ma y - o 2018 ISSN : 2249-5762 ... · These composites are fabricated using...

IJRMET Vol. 8, IssuE 2, May - ocTobER 2018 ISSN : 2249-5762 (Online) | ISSN : 2249-5770 (Print)

w w w . i j r m e t . c o m 20 INterNatIONal JOurNal Of reSearch IN MechaNIcal eNgINeerINg & techNOlOgy

Mechanical and Hygroscopic Properties of Hybrid Short Natural Fiber Composite Materials

1Ch. Krishnamohan, 2Ch. Venkateswara Rao, 3T.N.Charyulu1,2,3Dept. of Mechanical Engg., Sree Vahini Institute of Science & Tech., Tiruvuru, AP, India

AbtractIn recent years, natural fibers are under active consideration due to their abundant availability, low cost, ecofriendly, biodegradability, etc., for making various domestic and industrial products. Different natural fiber composites made of fibers from kenaf, sisal, hemp, etc., plants are being used extensively for making various non-structural parts like, automobile interiors, equipment casings, sports goods, toys, etc. In the present work, hybrid composites are made using short Hibiscus lampas and Borassus flabellifier fibers of different lengths and polyester resin. Mechanical properties like, tensile strength, impact strength, bending strength, hardness and water absorption properties are reported in this paper. The tensile strength is found to increase with the increase in length of the fibers whereas less water is absorbed for composites with longer fibers. We found that Hardness is increased with the increase of fiber length.

KeywordsHybrid Composites, Short Fiber Composites, Natural Fiber, Epoxy Resin Composites, Mechanical Properties, Hygroscopic Properties

I. Introduction

A. Preliminary RemarksFiber-reinforced composite materials are an important class of engineering materials that offer outstanding mechanical properties with flexibility in design and ease of fabrication. The advanced composites have the advantages of light weight, corrosion resistance, impact resistance and excellent fatigue strength. Today fiber composites are widely used in diverse applications such as automobiles, aircraft, containers and piping, sporting goods, electronics and appliances. These composites are fabricated using various reinforcing materials like glass fiber, carbon fibers, graphite, Kevlar fibers, etc. These fibers are non-biodegradable and offer environmental problems in disposing the scrap. The present trend of development of any technology should comply with the sustainable development and preserve the biodiversity. In view of this global concern, natural fiber reinforced composites are being envisaged that offer least problems to the environment and at the same time offer new and better materials to the society.The materials and products developed using natural fibers will not only have enhanced properties compared to the conventional thermoplastics or complete wood based products but also will be cost effective. The use of green composite materials is predicted to have tremendous market potential because of the increasing awareness of environmental issues such as biodegradation, renewable resources, and CO2 emission reduction through promotion of plantations. The researchers are exploring the application of various natural fibers like sisal, jute, kenaf, palmyra, etc., with matrix materials, epoxy resin.

B. Aim and Scope of the WorkIn the present work is aimed to prepare the laminates using the

fibers of Hibiscus lampas and Borassus flabellifier fibers of different lengths and polyester resin. Telugu vernacular name: Toddy palm fiber and General purpose ortho resin, unsaturated epoxy resin (ECMAS 4413& 8816). Mechanical properties like tensile, flexural strengths are evaluated as per ASTM standards.

C. Objectives and Justification of the PaperThe objective of the present proposal is to develop biodegradable composite products using natural fibers from hibiscus lampas, borasuss flabellifier that belongs to the MALVACEAE family and its Telugu vernacular name is adavibenda and thati.

The aim of this Project is to project the potential of natural • fiber composites and promote their production on commercial basis.It is aimed to encourage more plantations that yield fibers • and to provide employment in the agriculture and handloom weaving sectors and develop cottage industries in the rural areas.The entire activity is aimed to develop new materials for • enhanced performance and for the sustainability of the environment for the generations to come.

The Hibiscus lampas trees and borasuss flabellifier are abundantly found in the forest areas of A.P. the stem yield strong fibers that are traditionally used by the farmers in domestic and agricultural applications. Observing these features, the Hibiscus lampas and borasuss flabellifier fibers have been chosen to produce green composite products that can be used for several applications such as panels in construction, casings for various domestic products, packaging applications, sport goods etc.

II. Theoretical Background

A. Definition of Composite MaterialA composite is a structural material which consists of two or more constituents. These constituents are combined at a macroscopic level and are not soluble in each other. One constituent is called the reinforcing phase and the other is called the matrix. For a material to be composite conditions to be satisfied are: both constituents have to be present in reasonable proportions, composite properties are noticeably different from the properties of the constituents.

1. FibersA large variety of fibers are available as reinforced for the composite. The desirable characteristics of most reinforcing fibers are high strength, high stiffness and relatively low density. A great majority of materials are strong and stiffer in the fibrous form than as the bulk material. Therefore, fibers are very effective and attractive reinforcement materials. Different reinforcing fibers are glass fibers, carbon and graphite fibers, aramid fibers and natural fibers like jute, sisal, flax, screw pine etc.

2. MatrixThe matrix serves to bind the fibers together and transfer loads to the fibers and protects them against environmental attack and damage

IJRMET Vol. 8, IssuE 2, May - ocTobER 2018

w w w . i j r m e t . c o m INterNatIONal JOurNal Of reSearch IN MechaNIcal eNgINeerINg & techNOlOgy 21

ISSN : 2249-5762 (Online) | ISSN : 2249-5770 (Print)

due to handling. Matrix has strong influence on the mechanical properties as well as on the selection of fabrication process. Polyester and epoxy resins are the most common polymeric matrix materials used with high performance reinforcing fibers.

B. Classification of CompositesThe composites materials are classified based on the type of matrix material and the type of reinforcement used.

1. Based on type of Matrix Material

(i). Polymer Matrix Composites (PMC)The most common advanced composites are PMC. These composites consists of a polymer (e.g., epoxy, polyester, urethane) reinforced by thin diameter fibers (e.g., graphite, aramids, boron). The advantages are: low cost, high strength, and simple manufacturing principles and the drawbacks are: Low operating temperature, high coefficients of thermal and moisture expansion and low elastic properties.

(ii). Metal Matrix Composites (MMC)The matrix materials are: Aluminum, Magnesium, Titanium and the fibers are: Carbon, Silicon carbide. Metals are mainly reinforced to increase elastic stiffness and strength, decrease large coefficient of thermal expansion and electrical conductivities. The disadvantages are: higher processing temperatures and densities.

(iii). Ceramic Matrix Composites (CMC)The matrix materials are: Alumina (Al2O3), Calcium aluminosilicate and the fibers are: Carbon, Silicon carbide (SIC). The advantages are: high strength, hardness and high service temperate.

2. Based on Type of Reinforcement

(i). Particle Reinforced CompositesThese composites consist of particles immersed in matrices such as alloy and ceramics as shown in fig. 1. The shape of reinforcing particles may be spherical, cubic or any regular or irregular geometry. They are usually Isotropic, since particles are added randomly. These composites have improved strength, increased operating temperature and oxidation resistance.

Fig. 1: Particle Reinforced Composites

(ii). Fiber Reinforced CompositesThese composites consist of matrices reinforced by short (discontinuous) or long (continuous) fibers as shown in Fig. 2. Generally these are anisotropic.

Fig. 2: Fiber Reinforced Composites

C. Advantages and Disadvantages of Synthetic Fiber CompositesThe advantages are:

Composites are having high strength to weight and stiffness • to weight ratios.Composites can also have other attractive properties, such • as fatigue and impactResistance, corrosion resistance, high thermal or electrical • conductivity, and a low coefficient of thermal expansion etc.We can lower the overall mass of material without losing its • strength and stiffness.Another key factor for using the composites is metals and • alloys can’t always Meet the required demands.Even if we increase the strength by alloying, but they can’t • withstand at higher temperatures as compared to composites because of their high coefficient of thermal expansion.

The disadvantages are:Difficult to recycle.• High production cost.• Environmentally not safe.•

The life cycle diagram of glass fiber reinforced composites is shown in fig. 3.

Fig. 3: Life Cycle Diagram of Glass Fiber Reinforced Plastics

D. Natural Fiber CompositesWith the increased knowledge about the nature and its resources, the humans have developed more and more skills in its exploitation. They started creating faster machines, bigger toys, without due consideration to the effects on the environment or on the people. Some worried scientists and engineers have realized that they need to take responsibility for the outcome of their work. Their concern for the future generations has led to the concepts and terms



such as: green, eco, sustainable and environmentally friendly etc. This article reiterates the historical applications and the present day need for their renewed usage for sustainable development, the development that meets the needs of the present without compromising the ability of the future generations to meet their own needs. The life cycle diagram of natural fibre reinforced composites is shown in fig. 4.

Fig. 4: Life Cycle Diagram of Natural Fiber Reinforced Plastics

E. Advantages and Applications of Natural Fiber Composites

1. Advantages of Natural FibersThese are environmentally superior• Low cost• Less weight• Availability from renewable sources• Low density• Enhanced energy recovery• Can be thermally recycled (posses a good calorific value)•

2. ApplicationsApplications of natural fiber composites are shown in Figs. 3.6 to 3.10.

Railings• Fencings• Window door profiles• Computer monitor, mobile phone covers• Seat backs•

III. Specimen Preparation and Testing

A. Preparation of SpecimensSpecimens for tensile test, flexure test, impact test and water absorption test as per ASTM standards are prepared. The laminates are of 2mm thick. The dimensional details for each type of specimen are presented in respective diagrams.

B. Flexural Test SpecimenSpecimens for flexural test are cut from laminates as per ASTM D792 standards [6]. The standard dimensions for test specimen are shown in the fig. 5.

Fig. 5: Flexure Test Specimen Specimen for 5mm

ASTMD790 Flexural 5mm Specmen Before and After the Flexural Test

1. Flexural Graphs For 5 mm Specimen




2. Flexural Graphs for 7 mm Specimen



3. Flexural Graphs For 10 mm Specimen




C. Tensile Test SpecimenSpecimens are cut from laminates on a jig saw machine as per ASTM D 638 Standards [7]. The dimensions of the tensile test specimens are shown in the Fig.

ASTMD Standard 638 Tensile Specimen of 5 mm Lenth Before And After Test



1. Tensile Specimens Graphs For 5 mm




2. Tensile Graphs For 7 mm Specimen



3. Tensile Graphs for 10 mm Specimen




D. Water Absorption Test SpecimenSpecimens for Water absorption test are cut from laminates as per ASTM D 570 standards [9]. The standard dimensions for test specimen are shown in the fig. 6.

Fig. 6: Water Absorption Test Specimen

ASTMD Standard 570 Specimen of 5 mm Lenth Before and After Test



For 5mm specimenOriginal weight (w) = 0.007Change in weight (Δw) = 0.05Percentage of water absorption = (Δw-w) x 100/w =(0.05-0.007)x 100/0.007 = 86%For 7mm specimenOriginal weight (w) = 0.004Change in weight (Δw) = 0.05Percentage of water absorption = (Δw-w) x 100/w = (0.05-0.004) x 100/0.004 = 79%For 10mm specimenOriginal weight (w) = 0.006Change in weight (Δw) = 0.010Percentage of water absorption = (Δw-w) x 100/w = (0.010-0.006) x 100/0.006 = 52%

E. TestingTension and flexural tests are conducted on the specimens to compare the strengths between Hardwickia binata and glass fiber composites.

1. Flexural TestFlexural strength is the theoretical value of stress on the surface of the specimen at failure. It is calculated from the maximum bending moment by assuming a straight line stress- strain relation up to failure. When a beam of homogeneous, elastic material is tested in flexure as a simple beam supported at two points and loaded at the mid point, the maximum stress in the outer fiber occurs at mid span. This stress may be calculated for any point on the load deflection curve by the following equation S = (3 PL) / (2bd2)Where, S = Stress in the outer fiber at mid span in Kg/in2 P = Load at a given point in Kg L = Span in inches b = Width of beam tested in inches d = Depth of beam tested in inchesThe standard deviation can be calculated with the help of following formula s = Sqrt ( (Σ X2 – nXm2) / (n-1) ) s = Estimated standard deviation X = value of single observation n = number of observations Xm=arithmetic mean of the set of observations

IV. Results and Discussion

S.No fiber length (mm)

Tensile strength (MPa)

Flexural strength (MPa)

1 5 14.77 99.492 7 14.74 123.503 10 16.67 106.97

Results for Water Absorption TestIt is observed that the specimen has absorbed and the specimen has undergone. Warping and found a slight change in appearance of the specimen. It is also observed that the matrix has not absorbed any water but swelling has taken place only among the fibers through absorption of water from the edges of the specimen.

By increasing the fiber length and the mechanical properties are also increases up to certain limit. The maximum mechanical properties, tensile strength and flexural strength are found as 16.67MPa and 123.50MPa respectively. These mechanical properties are for the fiber length of 10mm and 7mm on further looking the water absorption was decreased by increasing the fiber length.

V. Conclusions and Scope For Future WorkIn this investigation, the effect of hybridization of hibiscus lamps fiber on the mechanical properties and the water absorption properties was studied. Conclusion from this study is as fallows

Marginal increase in mechanical properties is due to poor 1. interfacial bonding between the matrix and the fiber.Interfacial bonding between fiber and matrix will be improved 2. by chemical treatment [16-17].Hybridization of natural fiber composite by another natural 3. fiber does not yield superior mechanical properties as hybridization by glass fiber [6-7] and carbon fiber[16] hence this kind of hybrid composite are suitable for low cost applications.Moisture absorption study of hybrid composite shows the 4. minimum moisture uptake is by 50:50 hybrid composite.By observing the results, we may suggest that by changing 5. the resins and doing chemical treatment we can improve the results. Hibiscus lampas and Borassus flabellifer fibers plants may be encouraged for plantations.

However, it can be suggested that higher values of the strength parameters can be obtained by taking a randomly oriented hybrid laminate of two or more layers instead of a single lamina with more strands of fibers. Further, it can be suggested to use ECMALON Grade 4414 General purpose resin to achieve superior mechanical properties and water resistance.

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Publishing Limited, Cambridge, England, 2004.[2] Wambua P. Jan Ivens, Ignaas Verpoest, Natural Fibers:

cabn they replace glace glass fiber reinforced plastics?, Composites Science and Technolgy, vol. 63, No. 9, 2003, pp.1259-1264.

[3] Akesson D., Mikael Skrifvars, Jukka V.Seppala and Pernilla WalkenstrÖm, Preparation of Natural Fiber Composites from Biobased Thermoset Resins, Proceedings of the 27th Riso International Symposium on Materials Science, Denmark, 2006

[4] Joffe R., L. WallstrÖm and L.A. Berglund, Natural Fiber Composites Based on Flax-Matrix Effects, International Scientific colloquium: Modelling for Saving Resources, Riga, May 17-19, 2001.

[5] Khalid M., Salmiton, A. Chuah, T.G. Ratnam, C.T. Choong,




S.Y. Thomas, Effect of MAPP and TMPTA and Compatibilizer on the Mechnaical Properties of Cellulose and Oil Palm Fiber Empty Fruit Bunch-Polypropylene Biocomposites, Composite Interfaces, vol.15, Nos.2-3, 2008, pp.251-262.

[6] George J., I. Van De Weyenberg, J. Ivens and I. Verpoest, Mchanical Properties of Flax Fiber Reinforced EpoxyComposites, 2nd International Wood and Natural Fiber Composites Symposium, June 28-29, 1999 in Kassel /Germany.

[7] Karmakar A.C. and J.A. Youngquist, Injection Molding of Polypropylene Reinforced with Short Jute Fibers, Journal of Applied Polymer Science, vol. 62, 1996, pp.1147-1151.

[8] Santos P.A., Marcia A.S.Spinace, Karen K.G.Fermoselli, Marco-A.De Paoli, Polyamide-6/vegetal fiber composite prepared by extrusion and injection molding, Composites:Part A, vol.38, 2007, pp.2404-2411.

[9] Doan T.T.L., Hanna Brodowsky, Edith Mäder, Jute fiber/polypropylene composites II. Thermal, hydrothermal and dynamic mechanical behaviour, Composites Science and Technology, vol. 67, 2007, pp.2707-2714.

[10] T. Ramu, Development and Characterization of Biodegradable Hardwvikiya Bineta Rexb(Yepi) and Bauchinia Racemosa(Are) Natural fiber Composites, MTech. Dissertation, KITS, Kakatiya Univ. Warangal, 2008.

[11] [Online] Available: http://www.forest.nic.ap.in[12] Elinton S.de Medeiros, Jose A.M. Agnelli, Kuruvilla Joseph,

Laura H. de Carvalho, Luiz H.C. Mattoso, Mechanical Properties of Phenolic Composites Reinforced with Jute/Cotton Hybrid Fabrics, Polymer Composites, vol. 26, No.1, 2005, pp 1 – 11.

Channamal lu Kr i shnamohan Studying M.Tech (Machine Design) in Sree Vahini Institute of Science & Technology, Tiruvuru, Krishna (Dist), A.P., India.

Chitturi Venkateswararao Studied M.Tech in Nova College of Engg. & Technology, Janga Reddy Gudem, West Godawari (Dist). Working as a Asst. Professor in Sree Vahini Institute of Science & Technology, Tiruvuru, Krishna (Dist), A.P., India.

T. N. Charyulu Pursuing Ph.D from Bharath University. Working as a Associate Professor in Sree Vahini Institute of Science & Technology, Tiruvuru, Krishna (Dist), A.P, India.

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