ISO 9001:2000 Certified

DESIGNAND DEVELOPMENT OF SUGARCANE BAGASSE BASED FABRIC AND COMPOSITES

A PROJECT WORK

Submitted by

DEEPAK KUMAR.V 0810202010

KARTHIK.V 0810202022

KARTHIKEYAN.M.C 0810202024

MITHUN CHAKARAVARTHI.P 0810202305

in partial fulfillment for the award of the degree

of

BACHELOR OF TECHNOLOGY

IN

TEXTILE TECHNOLOGY

KUMARAGURU COLLEGE OF TECHNOLOGY, COIMBATORE-49

(An Autonomous Institution Affiliated to Anna University of Technology, Coimbatore)

BONAFIDE CERTIFICATE

Certified that this project report “DESIGN AND DEVELOPMENT OF SUGARCANE BAGASSE

BASED FABRIC AND COMPOSITES” is the bonafide work of “V.DEEPAK KUMAR, V.KARTHIK,

M.C.KARTHIKEYAN, P.MITHUN CHAKARAVARTHI” who carried out the project work under my

supervision.

SIGNATURE SIGNATURE

Mr. R.SENTHIL KUMAR Dr.BHAARATHI DURAI

Supervisor Professor and Head

Assistant Professor (SRG),Department of Textile Technology, Department of Textile

Technology,Kumaraguru college of Technology, Kumaraguru College of Technology, Coimbatore–

641049. Coimbatore –641049.

Submitted for the examination held on:……………

Internal Examiner External Examiner

TABLE OF CONTENTS

CHAPTER

NO.

TITLE PAGE NO.

ABSTRACT

LIST OF TABLES

LIST OF FIGURES

1 INTRODUCTION

1.1 Background of the Project

1.2 Significance of the Project

1.3 Project at glance

2 OBJECTIVES

3 LITERATURE REVIEW

4 METHODOLOGY

4.1 Alkali treatment

4.2 Properties

4.3 Testing of strength

4.4 Oil spilling test

4.5 Flammable test

4.6 Absorption load test

5 CONCLUSION

6 REFERENCE

ABSTRACT

Recycling is a key component of modern waste reduction in the today’s industry scenario. Recycling is

processing used materials (waste) into new products to prevent waste of potentially useful materials, reduce

the consumption of fresh raw materials, reduce energy usage, reduce air pollution (from incineration) and

water pollution (from landfilling) by reducing the need for "conventional" waste disposal, and lower

greenhouse gas emissions as compared to virgin production. Sugarcane is not only annually renewable

resources, but can also be turned into products normally made from plastic or paper. Bagasse is the sugarcane

fiber remaining after extraction of juice from sugarcane. Bagasse draws more and more attention because of

the increasing concern for disposal of agricultural residues and the need for enhancing the sugar cane

industry’s profitability. The appearance and handle of sugarcane bagasse is similar to bastfibre. Nonwovens

and Composites are the two product development techniques which find use in many applications in various

technical fields. There is a lack of research in utilizing the sugarcane bagasse as a textile raw material and in

producing textile based product. In order to produce sugarcane bagasse based textile product, characterization

of bagasse material is essential to sort out the end use application. The aim of our project is tocharacterize,

design and development of sugarcane bagasse material.

LIST OF TABLES

1.0 INTRODUCTION

1.1 BACKGROUND OF THE PROJECT:

For each 10 tons of sugarcane crushed, a sugar factory produces nearly 3 tons of wet bagasse. Since bagasse is

a by-product of the cane sugar industry, the quantity of production in each country is in line with the quantity

of sugarcane produced. Bagasse is considered a renewable material because it is the waste material from

sugarcane, a crop that is harvested annually. In addition, several bagasse products have been certified 100%

compostable by the Biodegradable Products Institute. Considering the above mentioned information,the

current project on the production of sugarcane bagasse based products and composites have been planned

eventually. The projects have been mainly planned with the aim of reusing of natural waste to make out a

usable and profitable product.

1.2 SIGNIFICANCE OF THE PROJECT:

The intention of this project is to developtextile material out ofbagasse. This project is also done with the eco-

friendly and biodegradable material which is theneed of the hour. Producing sugarcane bagasse based eco-

friendly products usually mean that their production or certainly use doesn't damage the environment. Another

aspect that goes into making bagasse based products is complete respect for the environment. Bagasse based

composites are not only safe for the environment, but they also help keeping your family protected from being

exposed to any toxic chemicals. Most standard-quality products nowadays contain the use of harmful

substances to a certain degree, which may potentially lead to cancer or other serious health problems. Cotton

has long been a dominant natural fiber in the textile industry. Low quality grieve fibers or low value textile

wastes predominantly consisting of cotton fibers that could not be used directly in the apparel industry, have

a high potential in the manufacturing of composite nonwovens that are quite promising materials in the

insulation market, especially in the automobile insulation market. At the same time, scientists and fiber

producers are exploring the use of alternative fiber crops (such as kenaf, jute, and hemp) and agricultural by-

products (such as sugar cane and rice by-products) which are presently underutilized. For example, in addition

to its high strength and porosity,bagasse fiber is biodegradable, environmentally friendly, and able to grow in

a wide range of climatic conditions and soil types. Agricultural residues and by-products of the sugar

industry, such as bagasse, could be used to produce a multitude of value-added non-food products, ranging

from fibers and composites, to films and resins. Until now, most of the bagasse has been compressed and

burned in-house by cane processors as a low calorie generating fuel, or has been utilized as raw material for

producing some low value-added products such as mulch and inexpensive ceiling tiles. Bagasse has also been

used to manufacture fiber boards and particle boards, but it was not competitive with products from other

woody sources. Bagasse fibers that were alkali extracted from the cane stalk in some previous research

conducted at Louisiana State University gave a new prospective solution. If a suitable method will be

established to convert bagasse fibers into useful technical nonwovens, this will enhance the profitability of

both sugar cane farming and mills. The utility of nonwoven products increased dramatically in the last decade

due to their light weight and low production cost. Nonwovens have found utility in automotive manufacturing,

building construction, medical applications, etc. There are two important steps in nonwoven manufacturing

that will influence the characteristics of the final product.The first is the forming of the fiber web, and the

second is the web bonding method. In the web forming procedure it is customary to blend two or more fibers

in order to improve the characteristics of the final product.

1.3 PROJECT AT A GLANCE:

Precisely, this project encompasses making of sugarcane bagasse based products and composites. This

involves a detailed work starting from sourcing of sugarcane bagasse, softening process, testing process like

thermal insulation, absorption tests etc...It also involves making of nonwoven products and composites. Thus

the significance of the project is achieved.

2.0 OBJECTIVES:

1) To characterize the sugarcane bagasse material.

2) To study and analyze the processing ability in spinning process.

3) To give pretreatment to enhance the processability in needle punching process.

4) To produce nonwoven based products from the sugarcane bagasse.

5) To produce composites from sugarcane bagasse.

6) To analyze various properties of the sugarcane bagasse fabric and composites.

3.0 LITERATURE REVIEW

3.1 Sugarcane Bagasse:

Bast fibers represent fibers that are obtained from the stem or stalk of the plants. Grasses such as sugar cane

have stems which contain bundles of fibers, but they are not classified as bast fibers. The difference comes

from the arrangement pattern of the fiber bundles; in regular bast fibers the bundles are in a definite ring

pattern, while in sugar cane they are more randomly dispersed. Nowadays several varieties of sugar cane are

used in agriculture. The sugar cane plants are known to grow best in tropical and subtropical regions.Sugar

cane stalk characteristics vary considerably depending on variety. Typical commercial varieties grown under

normal field conditions have a height of 1.5 to 3 meters and are 1.8 to 5 cm in diameter. The stalk surface can

be greenish, yellowish or reddish in color and is covered with a thin waxy layer.The fibro vascular bundles are

rather widely spaced in the central part of the stalk, but towards the periphery their numbers increase while

their sizes decrease. The bundles are composed of smaller ultimate fiber cells which are bound together by

lignin and hemicellulose.

Fibers in bagasse consist mainly of cellulose, pentosans, and lignin. Cellulose is a natural linear polymer and

has polymer chains of 2000 to 3000 units (Paturau, 1989) and a specific gravity about 1.55 (Elsunni, 1993).

Cellulose is highly crystalline regardless of the source. The ordered chains are tightly packed and have strong

intermolecular hydrogen bonding because of the preponderance of hydroxyl groups (Romanoschi, 1998). The

cellulose is present in three types: α, β, and γ. The α cellulose is known as pure cellulose, whereas β and γ

cellulose combined are called hemicellulose (Marthur, 1975). The hemicelluloses are chemically linked with

cellulose molecules. The other main compound in sugar cane fiber bundles is lignin which is a high molecular

weight substance. Because it is not possible to isolate lignin quantitatively from plant materials without

chemical or mechanical degradation, its true molecular weight is not known. The amount of lignin that

naturally occurs in sugar cane depends to a great extent on the variety and age of the cane.

R. Wirawan, S. M. Sapuan, Y. Rupiah and A. Khalil stated that“Sugarcane bagasse is divided into two major

components. They are pith and rind. Pith is the inner part of sugarcane bagasse while rind is the outer part of

it. In this study, the flexural properties of pith reinforced poly (vinyl chloride) composites were compared to

that of rind composites with the same matrix in variation of fiber content. The composites were produced by

compression moulding method. The fibre contents were 10%, 20%, 30%, 40%, and 50% in weight. Three-

point bending tests were carried out to measure the flexural properties of the composites. It has been found

that, in general, the addition of fiber improved the flexural modulus of the materials. Meanwhile, the rind

composites were of superior flexural properties compared to the pith composites”.

Rowellstatedthat “the cane stalk consists of inner pith that contains most of the sucrose, and an outer rind with

lignocelluloses fibers. Cane processing crushes the entire stalk to extract the sucrose, from which refined

sugar is produced. Large quantities of the bagasse, containing both crushed rind and pith fibers, remain after

sugar extraction. Disposal of this byproduct from the sugar industry is so far still inefficient”.

3.2 Sugarcane Bagasse in Composite Production:

NurSheliAkmaRamlistated that the bagasse fiber is a residue of a sugarcane milling process. In this research,

bagasse fiber has been used as filler in polypropylene (PP) resin to open up further possibilities in waste

management. The chemical treatment using polypropylene-graft maleic anhydride (MAPP) was carried out to

modify the fiber properties. The effect of fiber treatment and the fiber content on the composite properties

were studied. The compounding process was used as the PP/bagasse fiber composites fabrication. The

properties of PP/bagasse fiber composites were investigated through mechanical and physical testing. The

presence of MAPP as fiber treatment has accommodated better mechanical and physical properties for

PP/bagasse fiber composites. This has been proved by morphology studied which compatibilized PP/bagasse

composite has smooth surface without fiber pulled out. From tensile test, tensile strength and elongation at

break increased with increasing filler content while modulus of elasticity decreased for both compatibilized

and uncompatibilized PP/bagasse fiber composite. The addition of bagasse fiber in PP has decreased the

flexural strength and flexural modulus for both compatibilized and uncompatibilized PP/bagasse fiber

composites. Based on water absorption behaviour, it can be observed that the compatibilized PP/bagasse fiber

composites showed lower water absorption behaviour compared to the uncompatibilized one.

Increasingly, agricultural residues are being used to manufacture construction panel products such as

particleboard and the sturdier, more costly medium density fiberboard (MDF). In January, the Acadia Board

Company of New Iberia, Louisiana will begin producing particleboard made from bagasse, the fibrous portion

of sugar cane stalks that remains after removing the juice. The plant will use 50,000 tons of bagasse to

produce 18 million square feet of 3/4-inch board. The bagasse comes from the nearby Cajun Sugar

Cooperative, which processes sugar cane from 95 farmers. Although there are five other bagasse-to-

particleboard plants in the world, this is the first in North America. Acadia Board's product, called Dura Cane,

falls between the categories of particleboard and MDF, as do many agricultural fiber-based boards. Dura Cane

is expected to exceed ANSI standards for particleboard, but doesn't meet all of those for MDF. DuraCane is

bonded with MDI (methylene diphenyl diisocyanate), a formaldehyde-free resin. DuraCane's applications

include ready-to-assemble furniture, kitchen and bath cabinets, and laminate flooring.Typically, in the

sugarcane processing, large amounts of sugarcane bagasse are produced (approximately 240 kg of bagasse

with 50% humidity per ton of sugarcane), which are nowadays burnt in boilers for steam and

electricitygeneration. Better technologies for cogeneration and optimization of bioethanol production process

allow it to have a bagasse surplus (Ensinas et al., 2007), which may be used as a fuel source for electricity

generation or as raw material for producing bioethanol and other biobased products (Buddadee et al., 2008).

Bioethanol from lignocellulosic materials, such as sugarcane bagasse, has been studied for the past few

decades with great interest, but its production in industrial scale has not yet become viable (Balat et al., 2008).

3.3 Sugarcane Bagasse in Erosion Control Applications:

The range in diversity of these products will expand as new categories are introduced on the market. Also

standard methods are being developed to test their performance. Temporary Degradable erosion control

products are used to improve the establishment of vegetation. These products are used in places where

vegetation alone is sufficient in providing site protection after the temporary products have been degraded.

These products are being manufactured into rolls, named as Rolled Erosion Control Products (RECP). In this

category four types are included:

• Temporary Degradable – an RECP composed of degradable materials that reduces soil erosion and promotes

vegetation growth

• Erosion Control Net (ECN) – a natural fiber woven net or a geosynthetic mesh used either as a component

in the manufacture of RECPs, or separately, as a temporary degradable RECP to secure loose fiber mulches

• Open Weave Textile (OWT) – a temporary degradable RECP composed of processed natural or polymer

yarns woven into a matrix • Erosion Control Blanket (ECB) – a temporary degradable RECP composed of

natural or polymer fibers bound together, (mechanically or chemically), to form a continuous matrix

Long-term Non-degradable erosion control products composed of non-degradable materials intended to

supply erosion protection, increase vegetative growth and expand the erosion control performance limits of

vegetation. Included in this category are two types:

1. Long-term Non-degradable – a RECP composed of non-degradable materials.

2. Turf Reinforcement Mat (TRM) – a Long-term Non-degradable RECP that is usually buried to add

stability to the soil, composed from synthetic non-degradable filaments processed into a three dimensional

matrix. TRMs provide sufficient thickness and strength to permit soil retention and development of vegetation

within the matrix [17]. According to the Blue Book of Building and Construction there are 13 companies in

Louisiana marketing erosion control products [4]. Among them, Industrial Fabrics, Inc., Baton Rouge, LA, is

providing a large variety of erosion control blankets, turf reinforcement mats and accessories. Two of the most

effective products with a high demand on the market are the “Curlex” blankets manufactured by American

Excelsior Company, Arlington, TX and the straw blankets manufactured by North American Green,

Evansville, IN [23]. The Curlex blanket is fabricated from elongated randomly entangled fibers, usually

referred to as “wood wool” or simply “excelsior”. The fibers are held together by polypropylene that forms a

net on one or both sides of the blanket. This type of netting is photodegradable. The blanket-net assemblies

are then suitably packaged in individual rolls to facilitate easy handling and transportation to the erosion

control site. Here, the blankets are unrolled evenly and smoothly, without stretching the material, and then

anchored to the ground using wood or steel staples [1, 24].

Curlex blanket manufactured by American Excelsior Co. Despite the erosion control effectiveness of these

excelsior blanket-net assemblies and the other blankets formed using a similar pattern, erosion control

blankets of this general type have a distinct disadvantage. The problem relates to the use of netting material

fiber containment. Even though the netting may be photodegradable, it may last long enough to present

ecological problems. The net is capable of trapping birds and other small wildlife animals in their attempt to

nest or inhabit in the erosion control blankets. Until the netting material photo degrades, it does present an

impediment to normal activity. It would be a great advantage to provide an alternative to the netting material.

In this case, the net could be replaced with a bonding agent that would hold the fibers together such as heat,

glue or some other mechanical mean.

Sugarcane is grown in twenty four Louisiana parishes and is processed in thirteen mills. In current production

processes, cane is crushed to extract the juice. Bagasse is the “sugar technology term for the fibrous residue of

sugarcane after the application of the extraction process”.

Mill run bagasse, south Louisiana Sugars Cooperative, bagasse is an important material, suitable for many

applications. However, in the cane industry it is utilized as a source of energy generation by burning it in

steam boilers. Where there is an efficient energy economy, a cane sugar factory produces excess bagasse.

This excess can be converted into valuable products, like paper and fiberboards or used as fuel or animal feed.

The composition of the bagasse and its characteristics vary widely:

1. Water content: 45-55% (sometime higher)

2. Fiber content: 53-40%

3. Water soluble components: 2.5%

4. Insoluble ash content: 1% up to higher value, depending on, for example, contamination of the cane by soil

during harvest the actual composition depends on various factors. These include: the sugarcane variety, soil

conditions, agronomic techniques, climatic conditions as well as processing conditions.

3.4 Mechanical Processing of Sugarcane Bagasse:

a) Fiber and Pith

Bagasse fiber represents the water-insoluble material of the sugarcane. It is divided into two components with

almost the same chemical composition, but with a different structure: “true fiber” and pith. The true fibers are

represented by the tough, hard-walled, cylindrical cells of the rind and vascular tissue. The soft, thin-walled,

irregularly shaped parenchymatous cells of the inner stalks tissue represent the pith and they contain the

majority of the sucrose.

b) Bagasse Handling and Storage

Depending on the process plan of the factory and the fiber content of the sugarcane, surplus bagasse should be

understood as the bagasse that exceeds the required mass for energy production used in cane processing. This

surplus should not be confused with the temporary surplus which is stored for a short term to fill temporary

gaps in bagasse production due to interruptions of cane supply or extraction plant stoppages. Surplus bagasse

may be stored dry or wet, in bulk or baled, either as whole bagasse or depithed.

c) Bagasse Depithing

Depithing is the operation of separating the fibrous portion of bagasse (the rind) from the non-fibrous portion

(the pith). Usually bagasse has to be entirely depithed to improve pulping and pulp quality for uses in paper

and paperboard production. About 30% of the whole bagasse is represented by pith. There are three methods

for depithing:

1. Dry depithing

2. Moist depithing

3. Wet depithing

For the dry depithing the pith is removed by screening the bagasse. It is a simple and inexpensive

method, but dry bagasse creates a lot of dust, which is injurious to humans when inhaled. Moist depithing is

more suitable at the sugar factories. The bagasse that comes out of the milling plant has moisture of about

50% and can be immediately sent to the depithing equipment. In wet depithing, bagasse is mixed with water

in a vessel provided with a powerful agitator, to help remove the pith from the fibers. Wet depithing gives

clear fibers deprived more or less of the entire pith, but this method requires large quantities of water.

d) The Benefits of Depithing

Pith has undesirable properties especially in its low fiber length, which reduces the strength of the paper. Also

because pith has high absorption properties any attempt in the chemical treatment of bagasse will result in

high consumption of chemicals. If separated, pith can be used for burning fuel or animal feed, leaving the

fibers to be used in paper and fiberboard manufacturing. The depithing process is reducing the weight of the

bagasse therefore reducing the cost for the transportation.

e) Delignification Process

The amount of lignin that naturally occurs in sugarcane depends on the variety and age of the cane. The

amount of sugars, lignin and lignin-like compounds increases as the plant advances in age. The result is a

hardening of the fibers up to the time of tasseling, when the plant is considered fully mature. After the

flowering stage, the sugarcane plant is predisposed to consume its stock of sucrose and lignin as a result of the

physiological changes due to flowering. Because of the consumption of the organic compounds, the rind and

thus the fiber bundles become softer and elastic.

3.5 Composites:

Composites that forms heterogeneous structures which meet the requirements of specific design and function,

imbued with desired properties which limit the scope for classification. Composite materials are common

engineering materials which are designed and manufactured for various applications including automotive

components, sporting goods, aerospace parts, consumer goods, and in the marine and oil industries. The

growth in composite usage also came about because of increased awareness regarding product performance

and increased competition in the global market for lightweight components. Among all materials, composite

materials have the potential to replace widely used steel and aluminum, and many times with better

performance. Replacing steel components with composite components can save 60 to 80% in component

weight, and 20 to 50% weight by replacing aluminum parts. Contemporary composites results from research

and innovation from past few decades have progressed from glass fibre for automobile bodies to particulate

composites for aerospace and a range other applications.

A composite material is made by combining two or more materials to give a unique combination of

properties.Fibre-reinforced composite materials differ from the above materials in that the constituent

materials are different at the molecular level and are mechanically separable. In bulk form, the constituent

materials work together but remain in their original forms. The final properties of composite materials are

better than constituent material properties.

Modern materials engineers have used the composite concept—reinforcement in a matrix—to create a class of

modern materials that offers opportunities significantly greater than those of more common engineering

materials. One of the principal characteristics of all composites is that they have a reinforcement phase distinct

from the matrix phase. The individual characteristics of the two phases combine to give the composite its

unique properties. Composite materials can be classified based on matrices, reinforcement types and forms.

3.5.1 Reinforcements

The role of the reinforcement in a composite material is fundamentally one of increasingthe mechanical

properties of the neat resin system. All of the different fibres usedin composites have different properties and

so affect the properties of the compositein different ways. For most other applications,the fibres need to be

arranged into some form of sheet, known as a fabric, to makehandling possible. Different ways for assembling

fibres into sheets and the variety offibre orientations possible lead to there being many different types of

fabrics, each ofwhich has its own characteristics.

3.5.1.1 Properties of Reinforcing Fibres & Finishes

The mechanical properties of most reinforcing fibres are considerably higher thanthose of un-

reinforced resin systems. The mechanical properties of the fibre/resincomposite are therefore dominated by

the contribution of the fibre to the composite.The four main factors that govern the fiber’s contribution are:

1. The basic mechanical properties of the fibre itself.

2. The surface interaction of fibre and resin (the ‘interface’).

3. The amount of fibre in the composite (‘Fibre Volume Fraction’).

4. The orientation of the fibres in the composite.

3.6 Significance of Natural Fibre Composites:

Emergence of polymers in the beginning of the 19th century has provided the researcher the new dimensions to

use the natural fibre in more diversified fields. Recently, the use of natural fibres as reinforcement has become

increasingly important, and, owing to their different properties, the common methods for processing fibre-

reinforced plastics have to be adjusted to meet new and more demanding requirements. The environmental

pollution generated during the production and recycling of these synthetic based materials has once again

drawn the attention for the use of natural fibre.

Table . Types Of Natural Fibers And Their Physical Charecteristics.

Due to the light weight, high strength to weight ratio, corrosion resistance and other advantages, natural fibre

based composites are becoming important composite materials in building and civil engineering fields. In case

of synthetic fibre based composites, despite the usefulness in service, these are difficult to be recycled after

designed service life. However, natural fibre based composites are environment friendly to a large extent.

Table Sources And Applications Of Natural Fibers

3.7 Manufacturing of Composites

The mixture of reinforcement/resin does not really become a composite material until the last phase of the

fabrication, that is, when the matrix is hardened. After this phase, it would be impossible to modify the

material. Fabricating a composite part is generally concerned with placing and retaining fibres in the direction

and form that is required to provide specified characteristics while the part performs its design function. The

fabrication of composites is a complex process and it requires simultaneous consideration of various

parameters such as component geometry, production volume, reinforcement & matrix types, tooling

requirements, and process and market economics.

3.8 Compression Moulding:

Compression moulding is one of the oldest manufacturing techniques in the composites industry. The recent

development of high strength, fast cure, sheet moulding compounds bulk moulding compounds and

advancement in press technology is making the compression moulding process very popular for mass

production of composite parts.

The raw material for thermoplastic compression moulding process is glass mat thermoplastics (GMT). GMT

is primarily made from polypropylene resin and continuous but randomly oriented glass fibres. Melt-

impregnated GMT is the most common material form. Powder-impregnated, discontinuous fibre reinforced

GMT is also used.

A pre-weighed amount of a polymer mixed with chopped reinforcing fibres, hardening agent, anti-adhesive

agent and pigment (charge) is placed into the lower half of the mould. The charge may be in form of powders,

pellets, putty-like masses or pre-formed sheets. The charge is usually preheated prior to placement into the

mould. Preheated polymer becomes softer resulting in shortening the moulding cycle time.

After placing the laminate to be cured called the 'charge' in the core of the mould, the

cavity isthen closed at a rate of usually 4-12 mm/sec. In most cases the mould is

heated to 150°C (302°F), which causes the charge viscosity to be reduced.

Figure: Compression Moulding Machine (Opening)

With increasing mould pressure as the mould is closed, the charge flows towards the

cavity extremities, forcing air out of the cavity. The moulding pressure based on

projected part area ranges from 0.7 to 9 MPa (100 to 1200 psi). The upper half of the mould

moves downwards, pressing on the charge and forcing it to fill the mould cavity.

Figure: Assembling Of The Material In Compression Moulding Machine

Figure : Compression Moulding Machine Closed.

Higher moulding pressure causes sink marks, while lower pressure cause scumming of

the mould and porosity.The mould, equipped with a heating system, provides curing (cross-linking) of

the polymer matrix (if thermosetting resin is processed). The curing time is usually between 25 sec

to 3 minutes depending on several factors including' resin-initiator-inhibitor reactivity,

part thickness, component complexity and mould temperature.The mould is opened and the

part is removed from it by means of the ejector pin.

The resultant, compression-moulded parts possess a spectrum of properties, including high rigidity and

strength (tensile, compression, impact) and good surface properties (gloss, smoothness, paintability).In

principle, the thickness of compression-moulded compounds are not limited (in contrastto injection

moulding).The exertion of high pressure eliminates the problem of development of voids.

The primary advantage of the compression moulding is its ability of producing large

number of parts with little dimensional variations, if any, from part to part. A wide

variety of shapes, sizes and complexity can be produced by compression moulding.

Advantages

1. It is the one of the fastest techniques for making composite structural parts.

2. Because of higher productivity of the process, fewer tools and less labor are required.

Limitations

1. A high capital investment is required for the process.

2. The process is limited to high production volume environments.

3. The typical fibre volume fraction for this process is 20 to 30% because of the high viscosity of the resin.

4. The surface finish on the part is of an intermediate nature.

3.8 Testing of Composite Materials

Composite materials are both inhomogeneous and anisotropic in comparison to metallic materials that are

homogeneous and isotropic. The elastic properties of a material are a measure of its stiffness. This property is

necessary to determine the deformations that are produced by loads. The elastic properties of the composite

are determined by the elastic properties and volume fraction of the constituents (fibre and matrix) an

additionally by the orientation of the reinforcement. Elasticity theory can be used to determine the elastic

constants given sufficient information, however, the strength of a composite material is affected by a number

of parameters including fibre orientation, volume fraction of fibres, the amount of porosity, fibre length,

lamination layup and environmental effects.

3.8.1 Types of Loading

a) Tension

Figure: Tensile Stiffness

The response of a composite to tensile loads is very dependent on the tensile stiffness and strength properties

of the reinforcement fibres, since these are far higher than the resin system on its own.

b) Compression

Figure: Compression

The adhesive and stiffness properties of the resin system are crucial in determining the compression

properties, as it is the role of the resin to maintain the fibres as straight columns and to prevent them from

buckling.

c) Shear

Figure: Shear

This load is trying to slide adjacent layers of fibres over each other. Under shear loads the resin plays the

major role, transferring the stresses across the composite. The interlaminar shear strength (ILSS) of a

composite is often used to indicate this property in a multi-layer composite (‘laminate’).

d) Flexure

Figure: Flexural Property

Flexural loads are really a combination of tensile, compression and shear loads. When loaded as shown, the

upper face is put into compression, the lower face into tension and the central portion of the laminate

experiences shear.

3.9 Fibre Volume fraction

The fibre volume fraction of cured polymer-matrix composites can be obtained by a number of methods

including: matrix digestion, ignition loss, areal weight, and image analysis methods. Image analysis uses

digital imaging of a micrograph detailing the fibres and matrix. These methods generally apply to laminates

fabricated from most material forms and processes.

3.10 Tensile Testing

The basic physics of most tensile test methods are very similar: a prismatic specimen with a straight sided

gauge section is gripped at the ends and loaded in uniaxial tension. The principal differences between these

tensile test specimens are the specimen cross-section and the load-introduction method. By changing the

specimen configuration, many of the tensile test methods are able to evaluate different material

configurations, including unidirectional laminates, woven materials, and general laminates.

This test method provides procedures for the evaluation of tensile properties of single-skin laminates. The

tests are performed in the axial, or in-plane orientation. Properties obtained can include tensile strength,

tensile modulus, elongation at break (strain to failure), and Poisson’s ratio. For most oriented fiber laminates,

a rectangular specimen is preferred. Panels fabricated of resin alone (resin casting) or utilizing randomly

oriented fibers (such as chopped strand) may be tested using dog-bone (dumbbell) type specimens. The test

axis or orientation must be specified for all oriented-fiber laminates.

1. In-plane tension test

a)Straight-sided specimen tension tests

Figure: Straight Sided Specimen Tension Tests

In the tensile test method, a tensile stress is applied to the specimen through a mechanical shear interface at

the ends of the specimen, normally by either wedge or hydraulic grips. Composite materials are usually

gripped using some form of ‘friction grip’, where the load is transferred to the specimen through gripping

faces which are roughened with serrations or a cross-cut pattern. Parallel clamping grips, positively closed by

manual or hydraulic means, allow the operator to control the gripping force on the specimen. It has already

been noted that misalignment can be caused by inadequate grips. Bending of the specimen will also occur if

the fibre layers are not equally spaced, for instance as a result of poor consolidation. The material response is

measured in the gauge section of the specimen by either strain gauges or extensometers, and the elastic

material properties subsequently determined. Two-axis extensometers are available which measure lateral

contraction for Poisson’s ratio determination.

The important factors that affect tension testing results include control of specimen preparation, specimen

design tolerances, control of conditioning and moisture content variability, control of test machine-induced

misalignment and bending and consistent measurement of thickness. Fiber alignment, control of specimen

taper, and specimen machining (while maintaining alignment) are the most critical steps.

3.11 Compression Test

Most lightweight structures and substructures include compression members, which may be loaded in direct

compression, or under a combination of flexural and compressive load. The axial stiffness of compression

members can only be controlled by the cross-sectional area. The main difficulty in compression testing of

composites is prevention of buckling of the specimen. The ratio of compressive to tensile strength is low for

the highly anisotropic fibres, but the compressive strength of glass fibres is probably higher than their tensile

strength. The parameters found to be significant contributors to accuracy of the data include fabrication

practices, control of fibre alignment, improper and/or inaccurate specimen machining, improper tabbing

procedures if tabs are used, poor quality of the test fixture, improper placement of the specimen in the test

fixture, improper placement of the fixture in the testing machine, and an improper test procedure. The in-plane

compressive test methods are typically used to generate the ultimate compressive strength, strain-at-failure,

modulus, and Poisson’s ratio of axially or transversely loaded unidirectional composite specimens.

FIGURE : COMPRESSION TESTING MACHINE.

There are three basic methods of introducing a compressive load into a specimen: direct loading of the

specimen end, loading the specimen by shear, and mixed direct and shear loading. Compressive test methods

may also be further classified as having a supported or an unsupported test section to prevent buckling.

Unsupported test section method uses an unsupported gauge length loaded by shear loading. This test method

comprises two fixture types, the Celanese (conical wedge grips) and rectangular wedge grips. These fixtures

use tabbed or untabbed specimens and transfer load via wedge-type grips.

Another method applies a combination of end loading and shear loading to the test specimen. The fixture

comprises four blocks clamped in pairs to either end of the test specimen. The surfaces of the fixture blocks in

contact with the specimen are roughened, to increase the effective coefficient of friction and hence the shear

load transfer. The ratio between shear and end-loading is adjusted by the torque applied to the clamping bolts.

Because of the flexibility of this test method, many different types of composite materials may be tested.

Four point bending test uses flexure of a sandwich beam to determine compressive properties. The sandwich

beam method comprises a honeycomb-core sandwich beam that is loaded in four-point bending, placing the

upper face sheet in compression. The upper and lower face sheets are of the same materials and configuration.

The upper face sheet is designed to fail in compression when the beam is subjected to four-point bending. The

beam is loaded to failure in bending, resulting in the measurement of compressive strength, compressive

modulus and strain-at-failure if strain gauges are applied to the upper surface.

Axial compression testing is also useful for measurement of elastic and compressive fracture properties of

brittle materials or low-ductility materials. In any case, the use of specimens having large L/D ratios should be

avoided to prevent buckling and shearing modes of deformation.Specimens should have a uniform rectangular

cross section, 12 mm (0.5 inch) wide by 140 mm (5.5 inches) long.

3.12 In-plane & Interlaminar Shear Properties

Shear testing of composite materials has proven to be one of the most difficult areas of mechanical property

testing. While shear modulus measurements are considered accurate, the biggest difficulty is in measuring

shear strength. The presence of edges, material coupling, non-pure shear loading, non-linear behaviour,

imperfect stress distributions or the presence of normal stresses make shear strength determination

questionable.The most common specimen has a constant rectangular cross section, 25 mm (1 in) wide and 250

mm (10 mm) long.

3.13 Interlaminar Fracture

Interlaminar fracture, or delamination, continues to be one of the more serious failure modes for laminated

composite structures. Delamination arises from high out of plane loads where there are no fibres to resist these

loads. Delamination can occur from tensile, shear loads, or a combination of the two. Several methods to

characterize delamination have been developed which include.

a) Mode-I Fracture

The double cantilever beam (DCB) specimen has been widely used to measure the mode I interlaminar

fracture toughness, GICof composites. The DCB specimen is a laminate with a non-adhesive insert placed at

the mid-plane, at one end prior to curing or consolidation, to simulate a delamination. Generally,

unidirectional parallel sided specimens are used. Typically, loads are applied to the DCB via loading blocks or

hinges adhesively bonded to the surface of the DCB. During test, the specimen is subjected to displacement

controlled loading and usually experiences stable delamination growth allowing several values of G IC, to be

determined along the specimen's length. As the delamination grows, fibre bridging usually occurs increasing

the energy required to propagate the delamination further. Therefore, only the first value of GIC obtained from

delamination growth from the insert is unaffected by fibre bridging and can be considered a generic

interlaminar fracture toughness.

Figure: Mode 1- Fracture

b) Mode II- Fracture

There are several different test configurations for measuring mode II fracture toughness. The specimen

configuration is largely the same, it is the method of applying load to promote a mode II fracture that varies.

The configuration is a parallel, unidirectional beam as in the DCB. The three main method of loading the

specimen are:

End loaded shear - specimen is loaded as a cantilever in specialisedfixturing

End notched flexure - specimen is loaded in 3 point bending resulting in unstable delamination

growth.

4 end-notched flexure - as for the ENF except the specimen is loading in 4 point bending resulting in

stable delamination growth.

Figure:Mode 2 Fracture

The 4 end-notched flexure loading has advantages over the other tests. The 4-point bending loading fixture

uses rollers to support the specimen and to allow it to rotate freely. The upper loading rollers are allowed to

rotate about the vertical centre line of the fixture to account for the asymmetric bending of the specimen

caused by one half of the beam containing a delamination. The specimen is loaded in displacement control

and generally stable delamination results. Fibre bridging does not always occur for delamination grown in

mode II, however, delamination values at delamination initiation are generally used to quote mode II

toughness. However, there is significant friction between the delamination faces with this method.

A compliance calibration technique has been developed for the 4ENF specimen where the mode II fracture

toughness is determined from

GIIC = mpc 2/ b

pc - critical load at delamination initiation

b – Specimen width

m – Slope of the plot of the specimen compliance versus delamination length