mechanical and water absorption behavior of sisal and banana fiber composites

8/19/2019 Mechanical and Water Absorption Behavior of Sisal and Banana Fiber Composites

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CHAPTER 1

INTRODUCTION

A Composite Material is a macroscopic combination of two or more

distinct materials, having a recognizable interface between them . Composites

are used not only for their structural properties, but also for electrical, thermal,

tribological, and environmental applications. It consists of reinforcing stiffer

phase and the matrix phase. The resulting composite material has a balance of

structural properties that is superior to either constituent material alone.

Composites typically have a fiber or particle phase that is stiffer and stronger

than the continuous matrix phase and serve as the principal load carrying

members. The matrix acts as a load transfer medium between fibers, and in less

ideal cases where the loads are complex, the matrix may even have to bear loads

transverse to the fiber axis. The matrix is more ductile than the fibers and thus

acts as a source of composite toughness. The matrix also serves to protect the

fibers from environmental damage before, during and after composite processing. A hybrid composite is a !" composite which has more than one

fiber as a reinforcement phase embedded into a single matrix phase.

#ybridization provides the designers with an added degree of freedom in

manufacturing composites to achieve high specific stiffness, high specific

strength, enhanced dimensional stability, energy absorption, increased failure

strain, corrosive resistance as well as reduced cost during fabrication

Composites made of a single reinforcing material system may not be suitable if

it undergoes different loading conditions during the service life. #ybrid

composites may be the best solution for such applications.$ormally, one of the

fibers in a hybrid composite is a high% modulus and high%cost fiber and the other

is usually a low%modulus fiber. The high%modulus fiber provides the stiffness

and load bearing &ualities, whereas the low%modulus fiber ma'es the composite

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more damage tolerant and 'eeps the material cost low. The mechanical

properties of a hybrid composite can be varied by changing volume ratio and

stac'ing se&uence of different plies. #igh%modulus fibers are widely used in

many aerospace applications because of their high specific modulus. #owever,

the impact strength of composites made of such high%modulus fibers is

generally lower than conventional steel alloys or glass reinforced composites.

An effective method of improving the impact properties of high%modulus fiber

composites is to add some percentage of low%modulus fibers. Most composite

materials experience time varying internal disturbance of moisture and

temperature during their service life time which can cause swelling and

plasticization of the resin, distortion of laminate, deterioration of fiber(resin

bond etc. )ecause of the high performance laminates and composites especially

in aerospace, the effect of moisture(temperature environment has become an

important aspect of composite material behavior. In this pro*ect wor' the

behavior of sisal and banana hybrid composites with epoxy resin was described.

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1.1 WHY WE HAVE TAKEN THIS WORK?

The basic reason for wor'ing on such a topic arises from the fact that

composites are vulnerable to environmental degradation. A moist environment,

coupled with high or low temperature conditions is extremely detrimental for

composites. There have been several efforts made by researchers in the last few

years to establish the much needed correlation between the mechanical

properties of the material and the moist environment or similar hydrothermal

conditions, sub*ected to thermal shoc's, spi'es, ambient + sub ambient

temperatures. )ut most research has been on the mechanical aspects rather than

the physical + chemical interface and how this brings in change in the internal

mechanical properties and affects a variety of other morphological changes.

The focus of our research has been to understand the physical changes

that ta'e place at the bonding interface between the fibers and the matrix, as it is

of prime importance due to its lin' to the stress transfer, distribution of load, and

it also governs the damage accumulation + propagation. This has wide

significance in aerospace applications, because the aircraft components are

exposed to harsh moist environment.

#ence our pro*ect wor' aims at the mechanical characterization of the

sisal and banana fiber reinforced hybrid composites.

1.2 COMPOSITE MATERIAL

A composite material is defined as a material system which consists of

two or more distinctly differing materials which are insoluble in each other and

differ in chemical composition.

The ancient gyptians manufactured composites. -attle and daub is one

of the oldest man%made composite materials, at over /// years old.

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Examples

-ood is a good example of a natural composite, combination of

cellulose fiber and lignin. The cellulose fiber provides strength andthe lignin is the 0glue0 that bonds and stabilizes the fiber.

Adobe bric's are a good example for ancient composite. The

combination of mud and straw forms a composite that is stronger

than either the mud or the straw by itself.

Concrete reinforced with steel rebar.

1.! PHASES O" COMPOSITE MATERIALS

Composites are combinations of two phases.

Matrix phase.

!einforcement phase.

"#$ 1.1 P%ases &' (&mp&s#)e ma)e*#als

a+MATRI, PHASE

It is primary phase, having continuous character.

It holds the reinforcement phase.

More ductile.

2ess hard.

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Examples

"olymers.

Metals.

Ceramics.

-+REIN"ORCEMENT PHASE

It also called dispersed phase.

3tronger than matrix phase.

Examples

ibers.

"articles.

la'es.

1. PROPERTIES O" COMPOSITES

Composites can be very strong and stiff, yet very light in -eight,

so ratios of strength%to%weight and stiffness%to%weight are several

times greater than steel or aluminum.

atigue properties are generally better than for common

engineering metals.

Toughness is often greater than most of the metals.

Composites can be designed that do not corrode li'e steel.

"ossible to achieve combinations of properties not attainable with

metals, ceramics, or polymers alone.

1./ ADVANTA0ES O" COMPOSITE MATERIALS

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3tronger and stiffer than metals on a density basis for the same

strength, lighter than steel by 4/5 and aluminum by /5. #ence

3uperior stiffness%to%weight ratios.

ssentially inert in most corrosive environments. )enefits include

lower maintenance and replacement costs.

It can be compounded to closely match surrounding structures to

minimize thermal stresses.

Composites can be formed into many complex shapes during

fabrication, even providing finished, styled surfaces in the process.

The inherent characteristics of composites typically allow

production to be established for a small fraction of the cost that

would be re&uired in metallic fabrication.

6ood dimensional stability 7extremely low coefficient of thermal

expansion8.

1./ CLASSI"ICATION O" COMPOSITES

1./.1 ASED ON MATRI, MATERIAL

Metal Matrix Composites 7MMC8

Ceramic Matrix Composites 7CMC8

"olymer Matrix Composites 7"MC8

a+ Me)al ma)*#x (&mp&s#)es MMC+

The matrix in these composites is a ductile material. These composites can

be used at higher service temperature than their base metal counter parts. This

reinforcement in these materials may improve specific stuffiness, specific

strength, abrasion resistance, creep resistance and dimensional stability. The

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MMCs is light in weight and resist wear and thermal distortion, so it mainly

used in automobile industry. Metal matrix composites are much more

expensive those "MCs and therefore, their use are somewhat restricted.

-+ Ce*am#(3ma)*#x (&mp&s#)es CMC+

9ne of the main ob*ectives in producing CMCs is to increase the

toughness. Ceramics materials are inherent resistants to oxidation and

deterioration at elevated temperature: were it not for their disposition to brittle

racture, some of these materials would be idea candidates for use in higher

temperature and serve%stress applications, specifically for components in

automobile an air craft gas turbine engines. The developments of CMCs has

aged behind mostly for remain reason, most processing route involve higher

temperature and only employed with high temperature reinforcements.

(+ P&l4me* ma)*#x (&mp&s#)es PMC+

The most common matrix materials for composites are polymeric.

"olyester and vinyl esters are the most widely used and least expensive polymer

resins. These matrix materials are basically used for fiber glass reinforced

composites. or mutations of a large number resin provide a wide range of

properties for these materials. The epoxies are more expensive and in addition

to wide range of ranging commercials applications, also find use in "MCs for

aerospace applications. The main disadvantages of "MCs are their low

maximum wor'ing temperature high coefficients of thermal expansion and

hence dimensional instability and sensitivity to radiation and moisture. The

strength and stuffiness are low compared with metals and ceramics.

1./.2 ASED ON MATERIAL STRUCTURE

"articulate reinforcement composites 7"!C8

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iber reinforcement composites 7!C8

2aminar composites 72C8

a+ Pa*)#(5la)e *e#6'&*(eme6) (&mp&s#)es PRC+

"articulate reinforcements have dimensions that are approximately e&ual

in all directions. The shape of the reinforcing particles may be spherical, cubic,

platelet or any regular or irregular geometry. These composites can be classified

as two sub groups; i8 2arge particle composites ii8


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a reasonable price8. #ybrid composites are usually used when a combination of

properties of different types of fiber wants to be achieved, or when longitudinal

as well as lateral mechanical performances are re&uired.

#ybrid composites are more advanced composites as compared to

conventional !" composites. #ybrids can have more than one reinforcing

phase and a single matrix phase or single reinforcing phase with multiple matrix

phases or multiple reinforcing and multiple matrix phases. They have better

flexibility as compared to other fiber reinforced composites. $ormally it

contains a high modulus fiber with low modulus fiber.The high%modulus fiber

provides the stiffness and load bearing &ualities, whereas the low%modulus fiber

ma'es the composite more damage tolerant and 'eeps the material cost low. The

mechanical properties of a hybrid composite can be varied by changing volume

ratio and stac'ing se&uence of different plies.

1.7.1 ADVANTA0ES O" HYRID COMPOSITES

They offer better flexibility in the selection of fiber and matrix materials,

which helps in better tailoring of the mechanical properties. or example

the modulus, strength,fatigue performance etc of glass reinforced

composites can be enhanced by inclusion of carbon fibers.

)etter wear resistance

2ow thermal expansion coefficient

Combination of high tensile strength and high failure strain

)etter impact and flexural properties

!educed overall cost of the composite

2ow notch sensitivity

$on catastrophic

1.7.2 TYPES O" HYRID COMPOSITE

There are several types of hybrid composites characterized as;

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Interply or tow%by%tow, in which tows of the two or more constituent

types of fiber are mixed in a regular or random manner:

3andwich hybrids, also 'nown as cor%shell, in which one material is

sandwiched between two layers of another:

Interply or laminated, where alternate layers of the two 7ormore8

materials are stac'ed in a regular manner:

Intimately mixed hybrids, where the constituent fibers are made to mix as

randomly as possible so that no over%concentration of any one type is

present in the material: other 'inds, such as those reinforced with ribs,

pultruded wires, thin veils of fiber or combinations of the above.

1.7.! APPLICATION O" HYRIDS

#elicopter rotor blades and drive shafts.

Ailerons and floor panels of aircrafts.

In automobile sector they are used in transmission units, chassis

members,3uspensions, and structural body parts of cars and lorries.

C!"(A!" hybrids are used for ma'ing bicycle frames.

In sports industries Tennis rac&uets, fishing rods, s'is, golf club shafts,

yacht hulls,#oc'ey stic's and paddles

In medical world they are used for ma'ing orthoses.

1.7.! NATURAL "IER COMPOSITES

iber%reinforced polymer composites have played a dominant role for along time in a variety of applications for their high specific strength and

modulus. The manufacture, use and removal of traditional fiber=reinforced

plastic, usually made of glass, carbon or aramid fibers=reinforced thermoplastic

and thermoset resins are considered critically because of environmental

problems. )y natural fiber composites we mean a composite material that is

reinforced with fibers, particles or platelets from natural or renewable resources,

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in contrast to for example carbon or aramide fibers that have to be synthesized.

$atural fibers include those made from plant, animal and mineral sources.

$atural fibers can be classified according to their origin. The detailed

classification.

A6#mal "#-e*s M#6e*al "#-e*s Pla6) "#-e*s

Animal hair

3il' fiber

Avian fiber

Asbestos

Ceramic fibers

Metal fibers

3eed fiber

2eaf fiber

3'in fiber

ruit fiber

3tal' fiber

Ta-le 1.1 Class#'#(a)#&6 &' 6a)5*al '#-e*s

A6#mal "#-e*

Animal fiber generally comprise proteins: examples mohair, wool, sil',

alpaca, angora. Animal hair 7wool or hair8 are the fibers ta'en from animals or

hairy mammals. .g. 3heep>s wool, goat hair 7cashmere, mohair8, alpaca hair,

horse hair, etc. 3il' fiber are the fibers collected from dried saliva of bugs or

insects during the preparation of cocoons. xamples include sil' from sil'

worms. Avian fiber are the fibers from birds, e.g. feathers and feather fiber.

M#6e*al '#-e*

Mineral fibers are naturally occurring fiber or slightly modified fiber

procured from minerals. These can be categorized into the following categories;

Asbestos is the only naturally occurring mineral fiber. ?ariations are serpentine

and amphiboles, anthophyllite. Ceramic fibers includes glass fibers 76lass wood

and @uartz8, aluminium oxide, silicon carbide, and boron carbide. Metal fibers

includes aluminium fibers

Pla6) '#-e*

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"lant fibers are generally comprised mainly of cellulose; examples

include cotton, *ute, flax, ramie, sisal and hemp. Cellulose fibers serve in the

manufacture of paper and cloth. This fiber can be further categorizes into

following as ; 3eed fiber are the fibers collected from the seed and seed case

e.g. cotton and 'apo'. 2eaf fibe are the fibers collected from the leaves e.g. sisal

and agave. 3'in fiber are the fibers are collected from the s'in or bast

surrounding the stem of their respective plant. These fibers have higher tensile

strength than other fibers. Therefore, these fibers are used for durable yarn,

fabric, pac'aging, and paper. 3ome examples are flax, *ute, banana, hemp, and

soybean. ruit fiber are the fibers are collected from the fruit of the plant, e.g.

coconut 7coir8 fiber. 3tal' fiber are the fibers are actually the stal's of the plant.

.g. straws of wheat, rice, barley, and other crops including bamboo and grass.

Tree wood is also such a fiber. $atural fiber composites are by no means new to

man'ind. Already the ancient gyptians used clay that was reinforced by straw

to build walls. In the beginning of the /th century wood% or cotton fiber

reinforced phenol% or melamine formaldehyde resins were fabricated and used

in electrical applications for their non%conductive and heat%resistant properties.

At present day natural fiber composites are mainly found in automotive and

building industry and then mostly in applications where load bearing capacity

and dimensional stability under moist and high thermal conditions are of second

order importance. or example, flax fiber reinforced polyolefins are extensively

used today in the automotive industry, but the fiber acts mainly as filler materialin non%structural interior panels $atural fiber composites used for structural

purposes do exist, but then usually with synthetic thermoset matrices which of

course limit the environmental benefits.

The natural fiber composites can be very cost effective material for

following applications;

• )uilding and construction industry; panels for partition and false ceiling,

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partition boards, wall, floor, window and door frames, roof tiles, mobile

or pre%fabricated buildings which can be used in times of natural

calamities such as floods, cyclones, earth&ua'es, etc.

• 3torage devices; post%boxes, grain storage silos, bio%gas containers, etc.

• urniture; chair, table, shower, bath units, etc.

• lectric devices; electrical appliances, pipes, etc.

• veryday applications; lampshades, suitcases, helmets, etc.

• Transportation; automobile and railway coach interior, boat, etc.

$atural fibers are generally lignocellulosic in nature, consisting of helically wound cellulose micro fibrils in a matrix of lignin and hemicellulose.

According to a ood and Agricultural 9rganization survey, Tanzania and )razil

produce the largest amount of sisal. #ene&uen is grown in Mexico. Abaca and

hemp are grown in the "hilippines. The largest producers of *ute are India,

China, and )angladesh. "resently, the annual production of natural fibers in

India is about million tons as compared to worldwide production of about B

million tons. The detail information of fibers and the countries of origin are

presented in table 1.

"IERS COUNTRIES

lax )orneo

#emp ugoslavia, china

3un

hemp

$igeria, 6uyana, 3iera 2eone, India

!amie #ondurus, Mauritius

Dute India, gypt, 6uyana, Damaica, 6hana, Malawi, 3udan, Tanzania

Eneaf Ira&, Tanzania, Damaica, 3outh Africa, Cuba, Togo

3isal ast Africa, )ahamas, Anti&ua, Eenya,

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)anana India

Ta-le.1.2 "#-e*s a68 (&56)*#es &' &*#$#6

$atural fibres such as *ute, sisal, pineapple, abaca and coir have been

studied as a reinforcement and filler in composites. 6rowing attention is

nowadays being paid to sisal and banana fiber due to its availability and its

enhanced properties . #ence, research and development efforts have been

underway to find new use areas for sisal and banana, including utilization of

sisal and banana as reinforcement in polymer composites . Although there are

several reports in the literature which discuss the mechanical behavior of natural

fiber reinforced polymer composites. #owever, very limited wor' has been

done on mechanical behavior of sisal and banana fiber reinforced epoxy

composites. Against this bac'ground, the present research wor' has been

underta'en, with an ob*ective to explore the potential of sisal ans banana fiber

as a reinforcing material in hybrid composites and to investigate its effect on the

mechanical behavior of the resulting composites. The present wor' thus aims to

develop this new class of natural fiber based hybrid composites and to analyze

their mechanical behavior by experimentation.

1.9 SYNTHETIC "IRE COMPOSITES

Man%made fibres may come from natural raw materials or synthetic

chemicals. Many types of fibres are manufactured from natural cellulose,

including rayon: modal and the more recently developed 2yocell. Cellulose

based fibres are of two types, regenerated or pure cellulose such as from the

cupro%ammonium process and modified cellulose such as cellulose acetates.

Examples

6lass fibres

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Carbon fibres

Aramid fibres

The most common types of fibers used in advanced composites for

structural applications are the fiberglass, aramid, and carbon. The fiberglass is

the least expensive and carbon being the most expensive. The cost of aramid

fibers is about the same as the lower grades of the carbon fiber. 9ther high%

strength high%modulus fibers such as boron are at the present time considered to

be economically prohibitive.

Ca*-&6 "#-e*s

The graphite or carbon fiber is made from three types of polymer

precursors polyacrylonitrile 7"A$8 fiber, rayon fiber, and pitch. The tensile

stress%strain curve is linear to the point of rupture. Although there are many

carbon fibers available on the open mar'et, they can be arbitrarily divided into

three grades as shown in Table F. They have lower thermal expansion

coefficients than both the glass and aramid fibers. The carbon fiber is ananisotropic material, and its transverse modulus are an order of magnitude less

than its longitudinal modulus. The material has a very high fatigue and creep

resistance.

3ince its tensile strength decreases with increasing modulus, its strain at

rupture will also be much lower. )ecause of the material brittleness at higher

modulus, it becomes critical in *oint and connection details, which can have

high stress concentrations. As a result of this phenomenon, carbon composite

laminates are more effective with adhesive bonding that eliminates mechanical

fasteners.

A*am#8 '#-e*s

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These are synthetic organic fibers consisting of aromatic polyamides.

The aramid fibers have excellent fatigue and creep resistance. Although there

are several commercial grades of aramid fibers available, the two most common

ones used in structural applications are EevlarG H and EevlarG H. The oungs

Modulus curve for EevlarG H is linear to a value of 4F 6"a but then becomes

slightly concave upward to a value of 1// 6"a at rupture: whereas, for EevlarG

H the curve is linear to a value of 1 6"a at rupture. As an anisotropic

material, its transverse and shear modulus are an order of magnitude less than

those in the longitudinal direction. The fibers can have difficulty achieving a

chemical or mechanical bond with the resin

0lass "#-e*s

The glass fibers are divided into three classes , %glass, 3%glass and C%

glass. The %glass is designated for electrical use and the 3%glass for high

strength. The C%glass is for high corrosion resistance, and it is uncommon for

civil engineering application. 9f the three fibers, the %glass is the most

common reinforcement material used in civil structures. It is produced from

lime%alumina%borosilicate which can be easily obtained from abundance of raw

materials li'e sand. The fibers are drawn into very fine filaments with

diameters ranging from to1FJ1/% m. The glass fiber strength and modulus

can degrade with increasing temperature. Although the glass material creeps

under a sustained load, it can be designed to perform satisfactorily. The fiber

itself is regarded as an isotropic material and has a lower thermal expansion

coefficient than that of steel.Among these synthetic fibers, the fiberglass is the

least expensive and carbon being the most expensive. 3o the glass fiber uses in

most of the applications due its economic factor and its enhanced properties.

1.1: RESIN SYSTEMS

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The resin is another important constituents in composites. The two

classes of resins are the thermoplastics and thermosets. A thermoplastic resin

remains a solid at room temperature. It melts when heated and solidifies when

cooled. The long%chain polymers do not chemically cross lin'. )ecause they

do not cure permanently, they are undesirable for structural application.

Conversely, a thermosetting resin will cure permanently by irreversible cross

lin'ing at elevated temperatures. This characteristic ma'es the thermoset resin

composites very desirable for structural applications. The most common resins

used in composites are the unsaturated polyesters, epoxies, and vinyl esters: the

least common ones are the polyurethanes and phenolics.

a+ Ep&x#es

The epoxies used in composites are mainly the glycidyl ethers and

amines. The material properties and cure rates can be formulated to meet the

re&uired performance. poxies are generally found in marine, automotive,

electrical and appliance applications. The high viscosity in epoxy resins limits

it use to certain processes such as molding, filament winding, and hand lay%up.

The right curing agent should be carefully selected because it will affect the

type of chemical reaction, pot life and final material properties. Although

epoxies can be expensive, it may be worth the cost when high performance is

re&uired.

-+ V#64l Es)e*s

The vinyl ester resins were developed to ta'e advantage of both the

wor'ability of the epoxy resins and the fast curing of the polyesters. The vinyl

ester has higher physical properties than polyesters but costs less than epoxies.

The acrylic esters are dissolved in a styrene monomer to produce vinyl ester

resins which are cured with organic peroxides. A composite product containing

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a vinyl ester resin can withstand high toughness demand and offer excellent

corrosion resistance.

(+ P&l45*e)%a6es

"olyurethanes are produced by combining polyisocyanate and polyol in a

reaction in*ection molding process or in a reinforced reaction in*ection molding

process. They are cured into very tough and high corrosion resistance materials

which are found in many high performance paint coatings.

8+ P%e6&l#(s

The phenolic resins are made from phenols and formaldehyde, and theyare divided into resole and novolac resins. The resoles are prepared under

al'aline conditions with formaldehyde(phenol 7("8 ratios greater than one. 9n

the contrary, novolacs are prepared under acidic conditions with (" ratios less

than one. !esoles are cured by applying heat and(or by adding acids. $ovolacs

are cured when reacting chemically with methylene groups in the hardener. The

phenolics are rated for good resistance to high temperature, good thermal

stability, and low smo'e generation.

e+ P&l4es)e*s

It is produced by the condensation polymerization of dicarboxylic acids

and dihydric alcohols. The formulation contains an unsaturated material such as

maleic anhydride or fumaric acid which is a part of the dicarboxylic acid

component. The formulation affects the viscosity, reactivity, resiliency and heat

deflection temperature 7#


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modulus, and #


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. The filament winding process can be automated to wrap resin%wetted

fibers around a mandrel to produce circular or polygonal shapes.

F. The layup process engages a hand or machine buildup of mats of fibers

that are held together permanently by a resin system. This method

enables numerous layers of different fiber orientations to be built up to a

desired sheet thic'ness and product shape. The hand lay%up method is

simple one, easy to handle and low cost to manufacturing.


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"#$5*e 1.2 Des#$6 p%#l&s&p%4

or instance, using this integrated design philosophy, a composite

chassis%less trailer is manufactured with a F/ 5 weight reduction compared to aconventional trailer provided with a steel chassis.


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A polymeric composite materials is made up of at least two materials; a

fiber and a matrix. These are combined to exploit the individual characteristics,

thereby providing additional &ualities that they are unable to provide

individually .They differ mar'edly from metals in the following ways

Composites are mostly orthotropic and inhomogeneous.

6enerally stiffness is less than that of steels leading to greater

attention to local and overall structural stability.

Materials properties are influenced by the manufacturing process,

temperature and the environment.

urthermore, when comparing composite materials to metals it is found that;

They are lighter, leading to excellent specific strength and stiffness

values.

They have very good environmental resistance and do not corrode

li'e many metals.

They have readily formed into complex shapes.

They have low thermal conductivity.

A composite material can ta'e a number of different forms. The material

may be orthotropic, such as unidirectional reinforced polymer, where thestrength and stiffness in the fiber direction considerably exceeds that at H/ ° to

the fiber. It may be planer%isotropic, such as random chopped strand glass mat

reinforced polymer.

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"olymer composite materials consists of laminate of resin impregnated

fibers which are unidirectional or orthogonally aligned angle%ply or randomly

orientated systems. It is also possible to provide a mixture of fiber arrays in

laminate when fabricating a composite material to meet the re&uired loading

situation .This freedom to tailor%ma'e composite materials with specific

re&uired properties introduces an additional complexity in the design analyses

of these systems over those of the conventional ones.

"#-e* sele()#&6

The fiber reinforcement provides the structural performance re&uired of the final part. The fibers or filaments come in many chemical types and forms

and are the primary contributor to the stiffness, strength and other properties of

the composite.

Res#6 sele()#&6

They are viscous li&uids that are capable of hardening permanently. The

resins that are used in fiber%reinforced composites are sometimes referred to as

′ polymers′. "olymers can be classified under two types, according to the effect

of heat on their properties.

Thermoplastic !esins.

Thermosetting !esins 7"olyester and epoxy%#igh elastic model8.

Thermoplastics soften with heating and eventually melt, hardening again

with cooling. Typical thermoplastics include nylon, polypropylene, and A)3,

and these can be reinforcement, although usually only with short, chopped

fibers such as glass.

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Thermosetting materials, or ′thermosets′, formed from a chemical

reaction, where the resin and hardener or resin and catalyst are mixed and then

undergo a non%reversible chemical reaction to form a hard, infusible product.

The determination of whether to use a thermoplastic or thermosetting

resin depends largely on the application. Thermosetting resins are preferred

because of their increased ability to withstand elevated temperatures. It is

expected that the composite spring will be at a wor'ing temperature of 1// ° to

1///° and hence thermosetting resins are chosen as thermoplastic wor's well

only for cold and ambient wor'ing conditions.

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CHAPTER 2

LITERATURE REVIEW

=Me(%a6#(al a68 >a)e* a-s&*p)#&6 -e%a#&* &'

s#sal@-a6a6a '#-e* *e#6'&*(e8 p&l4es)e* %4-*#8 (&mp&s#)es -4

N.Ve6a)es%>a*a6 a68 A.Ela4ape*5malB presented that the

tensile, flexural, impact and water absorption tests were carried out

using banana(epoxy composite material. Initially, optimum fiber

length and weight percentage were determined. To improve the

mechanical properties, banana fiber was hybridised with sisal fiber.

This study showed that addition of sisal fiber in banana(epoxycomposites of up to B/5 by weight results in increasing the

mechanical properties and decreasing the moisture absorption

property. Morphological analysis was carried out to observe

fracture behaviour and fiber pull%out of the samples using scanning

electron microscope.

=S)584 &6 Me(%a6#(al C%a*a()e*#s)#(s &' U6#8#*e()#&6al

S#sal@0lass "#-e* Re#6'&*(e8 P&l4es)e* H4-*#8 C&mp&s#)es -4

Sa6a4.M.RB presented that this paper presents the mechanical

behavior of sisal(glass fiber reinforced polyester hybrid

composites. 3isal fiber has been hybridized with glass fiber

reinforced polyester using hand lay%up process to improve the

mechanical properties. Test specimens were prepared using glass

fiber768(sisal fiber of F/(G/, B/(B/ and G/(F/ weight fraction

ratios as per A3TM standards and mechanical properties li'e

tensile, impact and flexural strength of sisal (glass fiber reinforced

polyester are evaluated and compared. The results shows that

tensile strength of F/56%G/5sisal composition and flexural

strength of G/56%F/5sisal composition and impact 3trength of B/56%B/5sisal composition is found to be better than the

remaining two compositions .=Me(%a6#(al P*&pe*)#es &' Ep&x4 ase8 H4-*#8 C&mp&s#)es Re#6'&*(e8

>#)% S#sal@SIC@0lass "#-e*s -4 A*p#)%a.0.RB presented that development of

the "olymer Composites with natural fibers and fillers as a sustainable

alternative material for some engineering applications, particularly in aerospace

applications and automobile applications are being investigated. $atural fiber

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composites such as sisal, *ute, hemp and coir polymer composites appear more

attractive due to their higher specific strength, lightweight and biodegradability

and low cost. In this study, sisal(glass(3ic fiber reinforced epoxy composites are

prepared and their mechanical properties such as tensile strength, flexural

strength and impact strength are evaluated. Composites of silicon carbide filler

7without filler, F, + H-t 58 sisal fiber and glass fiber are investigated and

results show that the composites without filler better results compared to the

composites with silicon carbide filler.

2.1 OECTIVES O" THE RESEARCH WORK

The ob*ectives of the pro*ect are outlined below.

To develop a new class of hybrid polymer composites to explore the

potential of sisal and banana fiber.

valuation of mechanical properties such as; tensile strength, flexural

strength, tensile modulus, impact strength and water

absorption test.

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CHAPTER3!

MATERIALS METHODS AND PREPARATION O"

COMPOSITE

This chapter describes the details of processing of the composites and the

experimental procedures followed for their mechanical characterization. The

raw materials used in this wor' are

1. 3isal fiber

. )anana fiber fiber

F. poxy resin

. Alumina as filler

!.1 SISAL "IER

3isal fibre is derived from the leaves of the plant. It is

usually obtained by machine decortications in which the leaf is

crushed between rollers and then mechanically scraped. The fibre

is then washed and dried by mechanical or natural means. The

dried fibre represents only 5 of the total weight of the leaf. 9nce

it is dried the fibre is mechanically double brushed. The lustrous

strands, usually creamy white, average from 4/ to 1/ cm in length

and /. to /. mm in diameter. Then we have collected this sisal

fiber from 6opichettyplayam, rode. 3isal fibre is fairly coarse and

inflexible. It is valued for cordage use because of its strength,

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durability, ability to stretch, affinity for certain dyestuffs, and

resistance to deterioration in saltwater. 3isal fiber is fully

biodegradable, green composites were fabricated with soy protein

resin modified with gelatin. 3isal fiber, modified soy protein resins,

and composites were characterized for their mechanical and

thermal properties. It is highly renewable resource of energy. 3isal

fibre is exceptionally durable and a low maintenancewith minimal

wear and tear.

Chemical Composition of 3isal iber;

Kses of sisal fibre;

#igh grade sisal

fibres are long andare made into yarns

7either on their own

or in blends with wool

or acrylic8 and used in

carpets. Medium

grade fibres are made into cordage, ropes and twine, for agricultural and

industrial use: they are particular useful in a marine environment as they are

resistant to deterioration by salt water. 2ow grade shorter fibres are valued in

the paper industry because of the high content of cellulose and hemicellulose:

they help to strengthen recycled paper.

9ne of the traditional uses for sisal is baler twine, as the fibre is long

lasting and flexible. This use, however, has greatly decreased as the twine is

28

Cellulose B5

#emicelluloses 15

2ignin H.H5

-axes 5

Total 1//5

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being replaced by polypropylene and at the same time new harvesting

technology uses much less twine. 3isal is still the best material for ma'ing

dartboards. 3isal is used commonly in the shipping industry for mooring small

craft, lashing, and handling cargo.

3isal is being used in composites instead of fibreglass to reinforce

components if the automotive and aircraft industry. 3isal is also being used in

the construction industry as cement reinforcement for low cost housing, as

plaster reinforcement and for roofing materials, as well as insulation. 3isal is

also great as a buffing cloth as it is strong enough to polish steel, and soft

enough not to scratch it. Another use for sisal is as a geotextile in land

reclamation, stabilisation of slopes and road construction. It also ma'es good

cat scratching posts.

!.2 a6a6a '#-e*

)anana fiber, a ligno%cellulosic fiber, obtained from the

pseudo%stem of banana plant 7Musa sepientum8, is a bast fiber with

relatively good mechanical properties. )anana plant is a large

perennial herb with leaf sheaths that form pseudo stem. Its height

can be 1/%/ feet 7F./%1. meters8 surrounding with 4%1 large

leaves. The leaves are up to H feet long and feet wide 7.G meters

and /.1 meter8. )anana plant is available throughout Thailand and

3outheast Asian, India, )angladesh, Indonesia, Malaysia,

"hilippines, #awaii, and some "acific islands. Then we have

collected banana fiber from 6opichettypalayam, rode for this

research wor'.

C%a*a()e*#s)#(s &' a6a6a "#-e*

)anana fiber is a natural bast fiber. It has its own physical and chemical

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characteristics and many other properties that ma'e it a fine &uality fiber.

• Appearance of banana fiber is similar to that of bamboo fiber and ramie

fiber, but its fineness and spinnability is better than the two.

• The chemical composition of banana fiber is cellulose, hemicellulose, and

lignin.

• It is highly strong fiber.

• It has smaller elongation.

• It has somewhat shiny appearance depending upon the extraction +

spinning process.

• It is light weight.

• It has strong moisture absorption &uality. It absorbs as well as releases

moisture very fast.

• It is bio% degradable and has no negative effect on environment and thus

can be categorized as eco%friendly fiber.

• Its average fineness is //$m.

It can be spun through almost all the methods of spinning including ring

spinning, open%end spinning, bast fiber spinning, and semi%worsted spinning

among others.

APPLICATIONS O" ANANA "IER

In the recent past, banana fiber had a very limited application and was

primarily used for ma'ing items li'e ropes, mats, and some other composite

30

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materials. -ith the increasing environmental awareness and growing

importance of eco%friendly fabrics, banana fiber has also been recognized for all

its good &ualities and now its application is increasing in other fields too such as

apparel garments and home furnishings.

PROPERTIES O" ANANA "IER

!.! Ep&x4 *es#6

poxy resins are the most commonly used thermoset plastic

in polymer matrix composites. poxy resins are a family of

thermoset plastic materials which do not give off reaction products

when they cure and so have low cure shrin'age. They also have

good adhesion to other materials, good chemical and

environmental resistance, good chemical properties and good

insulating properties. The epoxy resins are generally manufactured by reacting epichlorohydrin with bisphenol.


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"#lle*

illers are particles added to composite material to lower the

consumption of more expensive binder material or to better some

properties of the mixtured material. Then the filler is used to

reduce the coefficient of thermal expansion and polymerization

shrin'age. It helps to improve the mechanical property of the

composite. In this connection, Alumina is used as filler. Then the

Alumina properties includes hard, wear resistant, xcellent size

and shape capability, high strength and stiffness.

!. METHODOLO0Y

The full methodology of this pro*ect wor' is shown

in figure F.F.

abrication by compression molding method

Testing of abricated iber composites

Testing of mechanical properties

"#$ !.! Me)%&8&l&$4

32

Tensile

test

lexural

test

Impact

test

-ater

absorption

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!.; "ARICATION O" COMPOSITE MATERIALS

This topic deals with the fabrication stages carried out to obtain

the composite material. The materials used in our fabrication

process are as follows;

3isal fiber fiber

)anana fiber

poxy resin

#ardner

Alumina 7Al/F8

!.;.1 COMPRESSION MOULDIN0 METHOD

The composite laminate is fabricated using compression

mouding method. It is simple and mostly used method. The

compression moulding process is shown in figure

"#$ !. C&mp*ess#&6 m&5l8#6$ p*&(ess

The process of composite fabrication using hand lay%up process is listed below,

Initially, the sisal fiber and banana fiber are chopped in the size of F mm.

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The fiber and Alumina is weighed to the re&uired &uantity and it also

mixed well.

Then, prepare the matrix by mixing the poxy resin and #ardener in the

ratio of 1/;1

Then the wax is applied in the die and the prepared matrix and fiber are

mixed well using glass rod.

Then the re&uired amount of fiber matrix is placed in the s&uare shaped

die of dimension F//xF//xF mm.

Then the die is closed and loaded with the pressure of 1B// psi at a

temperature of H/C

After hour, the die is opened and the hybrid laminate of sisal fiber and

banana fiber is ta'en out.

Ktmost care has been ta'en to maintain uniformity and homogeneity of

the composite. The fabricated specimen is shown in figure F..

"#$ !.; C&mp&s#)e Lam#6a)es

The composite laminate is fabricated for different fiber

weight 758, that is shown in table.

S.N& Samples "#-e*F+ "#lle*

758

Res#6

F+S#sal a6a6a

1 S1

2 S2

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! S!

S

; S;

Ta-le !.2 C&mp&s#)#&6 O' C&mp&s#)es

!./ E,PERIMENT PROCEDURE!./.1 CUTTIN0 O" LAMINATES INTO SAMPLES O"

DESIRED DIMENSIONS

A -I! #ACE3A- blade was used to cut each laminate

into smaller pieces, for various experiments and the sized

specimens are shown in the following figures.

T$3I2 T3T% 3ample was cut into the size of 7B/xBxF8mm in accordance

with A3TM standards


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-AT! A)39!"TI9$ T3T%3ample was cut into flat shape 7F/xF/xF8mm.

"#$ !.9 Wa)e* a-s&*p)#&6 )es) spe(#me6

T$3I2 T3T -IT# )92T D9I$T% 3ample was cut into the size of

71/xBxF8mm in accordance with A3TM standard


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!./.2 TENSILE TEST

The tensile strength of a material is the maximum amount of

tensile stress that it can ta'e before faliure.


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lexural strength is defined as a materials ability to resist

deformation under load. The short beam shear 73)38 tests are

performed on the composites samples to evaluate the value of inter%

laminar shear strength 7I2338. It is a F%point bend test, which

generally promotes failure by inter%laminar shear. This test is

conductedas per A3TM standard using KTM. The dimension of the

specimen is 71Bx1FxF8mm. It is measured by loading desired

shape specimen7x%inch8 with a span length at least three times

the depth. The flexural strength is expressed as 7M"a8 . lexural

strength is about 1/ to / percent of compressive strength

depending on the type, size and volume of coarse aggregate used.

#owever the best correlation for specific materials is obtained by

laboratory tests for given materials and mix design.

"#$ !.12 Expe*#me6)al se)5p '&* 'lex5*al )es)

!./. IMPACT TEST

Impact energy is the energy which is absorbed by the

specimen when the impact load is applied. #ere, the Izod impact

test is carried out. Izod impact testing is an A3TM standard method

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of determining the impact resistance of materials. An arm held at a

specific height 7constant potential energy8 is released. The arm hits

the sample and brea's it. rom the energy absorbed by the sample,

its impact energy is determined. A notched sample is generally

used to determine impact energy and notch sensitivity. The test is

similar to the Charpy impact test but uses a different arrangement

of the specimen under test.1N The Izod impact test differs from

the Charpy impact test in that the sample is held in a cantilevered

beam configuration as opposed to a three%point bending

configuration. The impact specimen size is 7Bx1FxF8mm.

"#$ !.1! I&8 #mpa() )es)#6$ ma(%#6e

!./.; WATER ASORPTION TEST

The water absorption test is used to find the water absorption rate. The effect of

water absorption on *ute and glass reinforced hybrid composites were

investigated . The specimens were dried in an oven at B/ /C and then they were

allowed to cool till they reached room temperature. The specimens were

weighed to an accuracy of /.1mg. -ater absorption tests were conducted by

immersing the composite specimens in distilled water in plastic tub at room

39

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temperature for hours duration. 9nce in hours, the specimens were ta'en

out from the water and all surface water was removed with a clean dry cloth and

the specimens were reweighed to the nearest /.1 mg. rom these two readings,

the water absorption rate 758 was calculated. The specimen size is 7F/JF/JF8

mm.

CHAPTER

MECHANICAL CHARACTERISTICS O" COMPOSITES

This chapter presents the mechanical properties of the sisal

and banana fiber reinforced epoxy composites prepared for this

present investigation.


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Ta-le .1 Me(%a6#(al p*&pe*)#es &' )%e (&mp&s#)es

.1.2. E""ECT O" "IER WEI0HT F+ ON TENSILE

STREN0TH

The test results for tensile strength are shown in igures .1.

The sample 1 and B shows the pure sisal and pure banana

reinforced composites and in this composites, pure banana shows

high tensile strength. The sample ,F and shows the tensile

strength of hybrid composites and in this hybrid composites, the

sample 7 i.e 1B5 of sisal and F/5 of banana fiber8 shows the

better tensile strength. rom the results it is seen that the tensile

strength of the composite increases with increase in banana fiber

weight758.

S1 S2 S3 S4 S0

5

10

15

20

25

30

Laminate samples

Tensile strength (N/mm2)

"#$5*e .1 E''e() &' '#-e* >e#$%) F+ &6 )e6s#le s)*e6$)%

&' (&mp&s#)es

.1.!. E""ECT O" "IER WEI0HT F+ ON TENSILE

STREN0TH WITH OLT OINT

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The test results for tensile strength are shown in igures .1. The sample 1 and B

shows the pure sisal and pure banana reinforced composites and in this

composites, pure banana shows high tensile strength. The sample ,F and

shows the tensile strength of hybrid composites and in this hybrid composites,

the sample 7 i.e F/55 of sisal and 1B5 of banana fiber8 shows the better

tensile strength. rom the results it is seen that the tensile strength of the

composite increases with increase in sisal fiber weight758.

12.5

13

13.5

14

14.5

15

15.5

16

Laminate samples

Tensile strength (N/mm2)

"#$5*e .! E''e() &' '#-e* >e#$%) F+ &6 )e6s#le s)*e6$)%

&' (&mp&s#)es

.1.!. E""ECT O" "IER WEI0HT F+ ON "LE,URAL

STREN0TH

The test results for flexural strength are shown in igures

.1. The sample 1 and B shows the pure sisal and pure banana

reinforced composites and in this composites, pure banana shows

high flexural strength. The sample ,F and shows the flexural

strength of hybrid composites and in this hybrid composites, the

sample F7 i.e 1B5 of sisal and F/5 of banana fiber8 shows the

better flexural strength. rom the results it is seen that the flexural

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strength of the composite increases with increase in banana fiber

weight758.

S1 S2 S3 S4 S5

0

10

20

30

40

50

60

Laminate samples

Flexural Strength (N/mm2)

"#$5*e .! E''e() &' '#-e* le6$)% &6 'lex5*al s)*e6$)% &'

(&mp&s#)es

.1.. E""ECT O" "IER WEI0HT F+ ON IMPACT

ENER0YThe test results for impact energy are shown in igures .1.

The sample 1 and B shows the pure sisal and pure banana

reinforced composites and in this composites, pure sisal shows

high impact energy. The sample ,F. and shows the impact

energy of hybrid composites and in this hybrid composites, the

sample 7 i.e F/55 of sisal and 1B5 of banana fiber 8 shows the

better impact energy. rom the results it is seen that the impact

energy of the composite increases with increase in sisal fiber

weight758.

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S1 S2 S3 S4 S50

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Laminate samples

Impact energy (J)

"#$5*e . E''e() &' '#-e* le6$)% &6 #mpa() e6e*$4 &'

(&mp&s#)es.

.1.; E""ECT O" "IER WEI0HTF+ ON WATER

ASORPTION RATE

The test results for water absorption rate are shown in

igures .1. The sample 1 and B shows the pure sisal and pure banana reinforced composites and in this composites, pure banana

shows less water absorption rate. The sample ,F and shows the

water absorption rate of hybrid composites and in this hybrid

composites, the sample F7 i.e .B5 of sisal and .B5 of banana

fiber 8 shows the less water absorption rate. rom the results it is

seen that the water absorption rate of the composite is less in

sample F.

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S1 S2 S3 S4 S50

5

10

15

20

25

Laminated samples

Water absrptin rate (!)

"#$ .; E''e() &' '#-e* >e#$%)F+ &6 >a)e*

a-s&*p)#&6 *a)e

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CHAPTER ;

COST ESTIMATION

This chapter presents the total cost of the pro*ect. The

process of cost estimation includes materials cost, fabrication cost

and cost of testing. The cost estimation is listed in table .1

S.NO DESCRIPTIONS


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CHAPTER /

CONCLUSIONS

This experimental investigation of mechanical behavior of sisal and banana

fiber reinforced epoxy hybrid composites leads to the following conclusions;

1. This wor' shows that successful fabrication of a sisal and banana fiber

reinforced epoxy hybrid composites with different fiber weight758 is

possible by compression molding techni&ue.

. It has been noticed that the mechanical properties of the composites such

as tensile strength, flexural strength, flexural modulus, impact strength

and water absorption rate of the composites are also greatly influenced by

the fibre weight758.

RE"ERENCES

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1. Eaw A.E.: Mechanics of composite materials, Chapter 1, C!C "ress; Taylor

+ rancis 6roup, K3A, //, nd ed. I3)$; /%4HF%1FF%/

. 6hassemieh, .: $assehi, ?. "olymer Composites. //1, , B4.


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1.Ohang, .: Lia, O. CMC, //B, , 1F.

mechanical and water absorption behavior of sisal and banana fiber composites

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