Mechanical and Water Absorption Behavior of Sisal and Banana Fiber Composites
Mechanical and Water Absorption Behavior of Sisal and Banana Fiber Composites
Mechanical and Water Absorption Behavior of Sisal and Banana Fiber Composites
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 FRP composite which has more than one
fiber as a reinforcement phase embedded into a single matrix phase.
Hybridization 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. Hybrid
composites may be the best solution for such applications.Normally, 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 qualities, whereas the low-modulus fiber makes the composite
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more damage tolerant and keeps the material cost low. The mechanical
properties of a hybrid composite can be varied by changing volume ratio and
stacking sequence of different plies. High-modulus fibers are widely used in
many aerospace applications because of their high specific modulus. However,
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. Because 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 project work the
behavior of sisal and banana hybrid composites with epoxy resin was described.
Examples:
Wood is a good example of a natural composite, combination of
cellulose fiber and lignin. The cellulose fiber provides strength and
the lignin is the "glue" that bonds and stabilizes the fiber.
Adobe bricks 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.
a)MATRIX PHASE:
It is primary phase, having continuous character.
It holds the reinforcement phase.
More ductile.
Less hard.
Examples:
Polymers.
Metals.
Ceramics.
b)REINFORCEMENT PHASE:
It also called dispersed phase.
Stronger than matrix phase.
Examples:
Fibers.
Particles.
Flakes.
Stronger and stiffer than metals on a density basis for the same
strength, lighter than steel by 80% and aluminum by 60%. Hence
Superior stiffness-to-weight ratios.
Essentially inert in most corrosive environments. Benefits 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 required in metallic fabrication.
Good dimensional stability (extremely low coefficient of thermal
expansion).
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 PMCs and therefore, their use are somewhat restricted.
Mineral Fibers
Asbestos
Plant Fibers
Seed fiber
Silk fiber
Ceramic fibers
Leaf fiber
Avian fiber
Metal fibers
Skin fiber
Fruit fiber
Stalk fiber
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, earthquakes, etc.
Storage devices: post-boxes, grain storage silos, bio-gas containers, etc.
Furniture: chair, table, shower, bath units, etc.
Electric devices: electrical appliances, pipes, etc.
Everyday applications: lampshades, suitcases, helmets, etc.
Transportation: automobile and railway coach interior, boat, etc.
Natural fibers are generally lignocellulosic in nature, consisting of
helically wound cellulose micro fibrils in a matrix of lignin and hemicellulose.
According to a Food and Agricultural Organization survey, Tanzania and Brazil
produce the largest amount of sisal. Henequen is grown in Mexico. Abaca and
hemp are grown in the Philippines. The largest producers of jute are India,
China, and Bangladesh. Presently, the annual production of natural fibers in
India is about 6 million tons as compared to worldwide production of about 25
million tons. The detail information of fibers and the countries of origin are
presented in table 1.2
FIBERS
Flax
Hemp
Sun
COUNTRIES
Borneo
Yugoslavia, china
Nigeria, Guyana, Siera Leone, India
hemp
Ramie
Jute
Hondurus, Mauritius
India, Egypt, Guyana, Jamaica, Ghana, Malawi, Sudan, Tanzania
Kneaf
Sisal
Banana
India
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. Other highstrength high-modulus fibers such as boron are at the present time considered to
be economically prohibitive.
Carbon Fibers
The graphite or carbon fiber is made from three types of polymer
precursors polyacrylonitrile (PAN) 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 market, they can be arbitrarily divided into
three grades as shown in Table 3.
coefficients than both the glass and aramid fibers. The carbon fiber is an
anisotropic 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.
Since its tensile strength decreases with increasing modulus, its strain at
rupture will also be much lower. Because of the material brittleness at higher
modulus, it becomes critical in joint 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.
Aramid fibers
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diameters ranging from 2 to1310-6 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. So the glass fiber uses in
most of the applications due its economic factor and its enhanced properties.
The two
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
required.
b) Vinyl Esters
The vinyl ester resins were developed to take advantage of both the
workability 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.
c) Polyurethanes
Polyurethanes are produced by combining polyisocyanate and polyol in a
reaction injection molding process or in a reinforced reaction injection molding
process. They are cured into very tough and high corrosion resistance materials
which are found in many high performance paint coatings.
d) Phenolics
The phenolic resins are made from phenols and formaldehyde, and they
are divided into resole and novolac resins. The resoles are prepared under
alkaline conditions with formaldehyde/phenol (F/P) ratios greater than one. On
the contrary, novolacs are prepared under acidic conditions with F/P ratios less
than one. Resoles are cured by applying heat and/or by adding acids. Novolacs
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 smoke generation.
e) Polyesters
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 (HDT). The viscosity controls the speed and degree of
wet-out (saturation) of the fibers. The reactivity affects cure time and peak
exotherm (heat generation) temperatures. High exotherm is needed for a thin
section curing at room temperature and low exotherm for a thick section.
Resiliency or flexible grade composites have a higher elongation, lower
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modulus, and HDT. The HDT is a short term thermal property which measures
the thermal sensitivity and stability of the resins.
The advantages cited in the unsaturated polyester are its dimensional
stability and affordable cost.
corrosion resistant and fire retardants. This resin is probably the best value for a
balance between performance and structural capabilities. From the above
statements, the polyester resin is used in this project work.
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This method
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CHAPTER 2
LITERATURE REVIEW
composites such as sisal, jute, 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/Sic 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
(without filler, 3, 6 & 9Wt %) 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 OBJECTIVES OF THE RESEARCH WORK
The objectives of the project are outlined below.
To develop a new class of hybrid polymer composites to explore the
potential of sisal and banana fiber.
Evaluation of mechanical properties such as: tensile strength, flexural
strength, tensile modulus, impact strength and water
absorption test.
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CHAPTER-3
MATERIALS, METHODS AND PREPARATION OF
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 work are
1. Sisal fiber
2. Banana fiber fiber
3. Epoxy resin
4. Alumina as filler
and
tear.
65%
Hemicelluloses
12%
Uses of sisal fibre:
Lignin
9.9%
are
Waxes
2%
or
or
Total
100%
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. Low grade shorter fibres are valued in
the paper industry because of the high content of cellulose and hemicellulose;
they help to strengthen recycled paper.
One 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
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Asian,
India,
Bangladesh,
Indonesia,
Malaysia,
of
Banana
Fiber
Banana fiber is a natural bast fiber. It has its own physical and chemical
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characteristics and many other properties that make it a fine quality fiber.
OF
BANANA
FIBER
In the recent past, banana fiber had a very limited application and was
primarily used for making items like ropes, mats, and some other composite
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29.98 g/denier
17.15
13.00%
6.54
1.70%
Extractives
Total Cellulose
Alpha Cellulose
Residual Gum
Lignin
81.80%
61.50%
41.90%
3.3 Epoxy resin
15.00%
Epoxy resins are the most commonly used thermoset plastic
in polymer matrix composites. Epoxy resins are a family of
thermoset plastic materials which do not give off reaction products
when they cure and so have low cure shrinkage. 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. Different resins are
formed by varying proportions of the two: as the proportion of
epichlorohydrin is reduced the molecular weight of the resin is
increased.
Curing of Epoxy Resins
Epoxy resins are cured by means of a curing agent, often
referred as catalysts, hardeners or activators. Often amines are used
as curing agents. In amine curing agents, each hydrogen on an
amine nitrogen is reactive and can open one epoxide ring to form a
covalent bond.
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Filler
Fillers 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
shrinkage. 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, Excellent size
and shape capability, high strength and stiffness.
3.4 METHODOLOGY
The full methodology of this project work is shown
in figure 3.3.
Fabrication by compression molding method
Tensile
Flexural
Impact
test
test
test
Water
absorption
Test
The fiber and Alumina is weighed to the required quantity and it also
mixed well.
Then, prepare the matrix by mixing the Epoxy resin and Hardener in the
ratio of 10:1
Then the wax is applied in the die and the prepared matrix and fiber are
mixed well using glass rod.
Then the required amount of fiber matrix is placed in the square shaped
die of dimension 300x300x3 mm.
Then the die is closed and loaded with the pressure of 1500 psi at a
temperature of 90C
After 24 hour, the die is opened and the hybrid laminate of sisal fiber and
banana fiber is taken out.
Utmost care has been taken to maintain uniformity and homogeneity of
the composite. The fabricated specimen is shown in figure 3.2.
S.No Samples
Fiber(%)
Sisal
S1
S2
Filler
Banana
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(%)
Resin
(%)
S3
S4
S5
TENSILE TEST WITH BOLT JOINT- Sample was cut into the size of
(102x25x3)mm in accordance with ASTM standard D-5868-01. Two plates are
made up of for same size and made the single lab joint for testing the tensile
strength. One hole is drilled at each plate at the size of 6mm diameter and the
single lab joint is made with the help of 6mm bolt and nut.
Fig 3.10 Tensile test specimen with bolt joint
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temperature for 24 hours duration. Once in 24 hours, the specimens were taken
out from the water and all surface water was removed with a clean dry cloth and
the specimens were reweighed to the nearest 0.1 mg. From these two readings,
the water absorption rate (%) was calculated. The specimen size is (30303)
mm.
CHAPTER 4
MECHANICAL CHARACTERISTICS OF COMPOSITES
This chapter presents the mechanical properties of the sisal
and banana fiber reinforced epoxy composites prepared for this
present investigation. Details of processing of these composites and
the tests conducted on them have been described in the previous
chapter. The results of various characterization tests are reported
here. This includes evaluation of tensile strength, flexural strength,
flexural modulus, impact strength and water absorption (%) has
been studied and discussed. The interpretation of the results and the
comparison among various composite samples are also presented.
Tensile
Flexural
Impact
Water
strength
strength
Energy(J)
absorption
S1
S2
S3
(MPa)
15.941
18.541
18.796
(MPa)
45.362
43.317
39.942
0.75
0.50
0.35
(%)
17.95
18.53
10.61
40
15
10
5
0
S1
S2
S3
Laminate samples
S4
The test results for tensile strength are shown in Figures 4.1. The sample 1 and 5
shows the pure sisal and pure banana reinforced composites and in this
composites, pure banana shows high tensile strength. The sample 2,3 and 4
shows the tensile strength of hybrid composites and in this hybrid composites,
the sample 2( i.e 30%% of sisal and 15% of banana fiber) shows the better
tensile strength. From the results it is seen that the tensile strength of the
composite increases with increase in sisal fiber weight(%).
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15.5
15
14.5
14
13.5
13
12.5
Laminate samples
S1
S2
S3
S4
S5
Laminate samples
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0.8
0.7
0.6
0.5
Impact energy (J) 0.4
0.3
0.2
0.1
0
S1
S2
S3
S4
S5
Laminate samples
4.1.5
EFFECT
OF
FIBER
WEIGHT(%)
ON
WATER
ABSORPTION RATE
The test results for water absorption rate are shown in
Figures 4.1. The sample 1 and 5 shows the pure sisal and pure
banana reinforced composites and in this composites, pure banana
shows less water absorption rate. The sample 2,3 and 4 shows the
water absorption rate of hybrid composites and in this hybrid
composites, the sample 3( i.e 22.5% of sisal and 22.5% of banana
fiber ) shows the less water absorption rate. From the results it is
seen that the water absorption rate of the composite is less in
sample 3.
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25
20
15
Water absorption rate (%)
10
5
0
S1
S2
S3
S4
S5
Laminated samples
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CHAPTER 5
COST ESTIMATION
This chapter presents the total cost of the project. The
process of cost estimation includes materials cost, fabrication cost
and cost of testing. The cost estimation is listed in table 6.1
S.NO
DESCRIPTIONS
QUANTITY
AMOUNT(Rs)
Sisal fiber
1 kg
350
Banana fiber
1 kg
400
Epoxy resin
1.5 litre
900
Hardner
100 ml
250
Alumina
100 ml
500
Fabrication cost
3000
Cutting of laminates
500
Testing
Total
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CHAPTER 6
CONCLUSIONS
This experimental investigation of mechanical behavior of sisal and banana
fiber reinforced epoxy hybrid composites leads to the following conclusions:
1. This work shows that successful fabrication of a sisal and banana fiber
reinforced epoxy hybrid composites with different fiber weight(%) is
possible by compression molding technique.
2. 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 weight(%).
REFERENCES
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