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International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 6, June 2017, pp. 722–731, Article ID: IJCIET_08_06_078
Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=6 ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication Scopus Indexed
PHYSICAL AND MECHANICAL
PERFORMANCE OF LUFFA-COIR FIBER
REINFORCED EPOXY RESIN BASED HYBRID
COMPOSITES
Vineet Kumar Bhagat
Research Scholar, Mechanical Engineering,
NIT Jamshedpur, Jharkhand (India)
Anil Kumar Prasad
Assistant Professor, Mechanical Engineering,
NIT Jamshedpur, Jharkhand (India)
Arvind Kumar Lal Srivastava
Professor, Civil Engineering,
NIT Jamshedpur, Jharkhand (India)
ABSTRACT
The present study is carried out on use of natural occurring fiber luffa and coir
to make a hybrid composite. Ten numbers of different samples are prepared which
have different compositions. The influence of fiber length variations and resulting
contents are investigated on characterization of coir fiber and luffa fiber reinforced
hybrid composites using epoxy resin as matrix materials. For this, hybrid composites
are manufactured using simple hand lay-up technique. These composites are
compared on the basis of mechanical properties such as strength, toughness, hardness
and density etc. The results are obtained from the various tests carried out as per
ASTM standard. It is found that the density and void content of composite specimen
increases with increasing fiber content, while increasing the fiber length, density of
composites are decrease. Results reveal that the maximum strength properties are
observed for the composite with 25 wt. % fiber content at 30 mm length. The tensile
modulus and micro-hardness values increases with increase in fiber loading and
length.
Key words: Coir Fiber, Epoxy Resin, Hybrid Composite and Luffa Fiber.
Physical and Mechanical Performance of Luffa-Coir Fiber Reinforced Epoxy Resin Based Hybrid
Composites
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Cite this Article: Vineet Kumar Bhagat, Anil Kumar Prasad and Arvind Kumar Lal
Srivastava, Physical and Mechanical Performance of Luffa-Coir Fiber Reinforced
Epoxy Resin Based Hybrid Composites. International Journal of Civil Engineering
and Technology, 8(6), 2017, pp. 722–731.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=6
1. INTRODUCTION
The recyclability, neutrality of carbon dioxide and environmental friendly way of recovery
makes the natural fibers very important in today’s scenario. Fibers Luffa and coir are
increasing demand due to its environmental friendly, easily availability, marked its values in
composite engineering. It is increased day by days due to its minimum cost comparable to
man-made fibers like carbon, Kevlar, glass which are petrochemical based products. Mallik et
al. [1] presented that Bios fiber composites are fabricated using natural occurs or petroleum
based resin with reinforced as naturally occurring fibers. Lower manufacturing cost,
renewable, higher specific properties, lower density and lighter are its quick advantages have
been studied by Nunna et al. [2] and Verma et al. [3]. Many investigations have been done to
investigate the ability of natural occuring fibers as reinforcement mainly in polymers.
According to Satyanarayana et al. [4] comparatively less aggregated value can utilize only
small quantity of coir fibers. The investigation carried out by monteiro et al. [5] and hill et al.
[6] have found that banana-coir fibers are not much effective reinforcement to utilize in
composites with polymer matrix. Lignocelluloses surface of the hydrophilic coir fiber absorb
water which causes prevention of an efficient adhesion to the hydrophilic polymer matrix
which also happen in other natural fiber composite have been reported by Gassan et al. [7].
Monteiro et al. [8] gives, if the coir fiber undergoes strong alkali treatment, it improves the
adhesion of the fiber to the matrix of polyester and thus increases the strength of the
composite by a rough value of 50% for 30 % volume fraction of coir fiber. Thinner coir fiber
could also be another possibility to reinforce the matrix effectively thus increasing the
strength of the composite.
Monteiro et al. [9] further fabricated a composite with fiber of sisal, ramie and curaua of
thinnest section size in their work and the output suggested improved polymer matrix
composite properties in mechanical behavior. It was observed that the level of flexural
strength of these composite was more than 30 % of the corresponding values obtained for
identical composite with non-selected, average diameter, fiber. Many authors [10-12] have
carried out their studies in this area. They found that the reinforcement of natural fiber into
polymer could improve desired properties. Mechanical behavior of Sisal/jute/glass fiber
reinforced unsaturated polyester composite were studied by Ramesh et al. [13].result gives
that addition of glass fiber in sisal/jute fiber improve the mechanical properties.
Venkatshwaran et al. [14] investigated the tensile behavior of banana/sisal fiber reinforced
hybrid composites. Result shows that experimental values are lower than the hybrid mixture
rule because of void formation in between reinforcement and resin during fabrication.
Devireddy et al. [15] studied the physical and mechanical behavior of banana/jute fiber
reinforced hybrid composites. Result shows that the mechanical properties are significantly
affected by fiber loading. Since most data, in literature cover only a specific loading fraction
of fiber, this work was aimed to develop a novel class of hybrid composite materials covering
a small range of fiber weight fraction, and length, with the use of two different types of
natural fiber that is short coir fiber and Luffa mat and study their physical and mechanical
behavior.
Vineet Kumar Bhagat, Anil Kumar Prasad and Arvind Kumar Lal Srivastava
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2. EXPERIMENTAL WORK
2.1. Materials preparation
Coir fiber has been procured from local sources, Alleppey, Kerala, India and Luffa fiber
obtained from local sources of Jharkhand. Epoxy resin (LY 556) and corresponding hardener
(HY951) supplied by Ciba Geigy India Ltd. The bark and seed were removed from luffa
vegetable carefully. After that luffa fiber were cut carefully and make mat like structure
whose dimension was 140mm×100mm. Coconut coir fibers were first cut to the different
length (15, 20, 25, 30 and 35) mm. By using hand lay-up technique the various types of
composite materials were fabricated. Composite mat of uniform thickness was prepared from
Luffa fiber and short coir fiber of particular fiber length. Both fibers are reinforced with
epoxy resin. The low temperature curing Araldite LY556 epoxy resin and corresponding
HY951 hardener is mixed with the ratio of 10:1 by weight percentage. The different hybrid
composite sheet was prepared with the variation of fiber length (fiber weight fraction
constant) and weight fraction (keeping the fiber length constant). For quick and easy removal
of the fabricated composite plate silicon free spray as a releasing agent was also put over the
metal plate. Mould release spray was also applied to the inner surface of the mould wall after
it was set on the metal plate. Pressure was then applied from the top and the mould was
allowed to cure at room temperature for 72 hrs. After curing the composite was cut into
required size of the physical and other mechanical test by the heck saw.
2.2. MECHANICAL TESTING
Micro-hardness is done using a Leitz micro-hardness tester. vikers harness number is
calculate using the following equation.
20.1889V
FH
L= (1)
And 2
X YL
+=
Where, F is the applied load, L is the diagonal of square impression, X and Y are the
horizontal and vertical length, measured in N, mm, mm and mm, respectively.
The density of composite materials in term of weight fraction is found from the following
equation.
( ) ( )o
ct
o a b
ws =
w + w -w (2)
Where Sct represent specific gravity of the composite, Wo represent the weight of the
sample, Wa represent the weight of the bottle and kerosene, and Wb represent the weight of
the bottle and kerosene and sample.
The actual density of the composite is calculated using the following equation.
ca ct ksρ ρ= × (3)
Where caρ represent actual density of composite and
kρ represent density of kerosene.
The theoretical density of composite materials in term of weight fraction can easily be
obtained from the following equation.
Physical and Mechanical Performance of Luffa-Coir Fiber Reinforced Epoxy Resin Based Hybrid
Composites
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1f m
ct
f m
w wρ
ρ ρ
= +
(4)
Where ᴡ and ρ represent weight fractions and density. The suffix f, m and c stand for the
fiber, matrix and the composite materials, respectively.
The void content of composite sample has been determined as per ASTM D-2734-70
standard procedure. The volume fractions of void (Vv) in the composites are calculated by
using an equation.
ct ca
v
ct
Vρ ρ
ρ
−= (5)
Where ctρ and caρ are the theoretical and actual density of the composite, respectively.
The tension test is generally performed on flat specimens. The tensile tests were
conducted according to the ASTM D 3039-76 standard on a computerized universal testing
machine INSTRON. The spam length of the test specimen used was 42 mm. The test was
performed with a constant strain rate of 2 mm/min. the tensile strength was found out by using
the following equation.
.F
T SA
= (6)
Where F is the maximum load (N); A is the cross-sectional area of the sample
Flexural test is performed using 3-point bending test according to ASTM D790-03
standard procedure. Specimen of 150 mm length and 15 mm wide are taken and tested in
three point bending test at a crosshead speed of 5 mm/min. The test is conducted on the same
machine used for tensile test. The flexural strength (F.S) is computed using the following
equation.
23.
2FLF S
bt= (7)
Where F is the maximum load, L is the distance between the supports, b is the width of
the specimen and t is specimen thickness measured in N, mm, mm and mm, respectively.
Low velocity instrumented impact tests are carried out on the specimen. The standard
specimen size is taken as per ASTM D 256 is 64 mm × 12.7 mm × 4 mm where the depth of
the notch is 2 mm. Respective values of the impact energy of different specimen are recorded
directly on the dial indicator.
3. RESULTS AND DISCUSSIONS
3.1. Hardness, Density and Void Formation
Micro-hardness and density of the composites are inter-related. The effect of fiber length and
content on hardness, density and void are given in table 1. It is analyzed from the table the
micro-hardness of composite increases as the length of fiber increase. Similarly, as the fiber
content, the micro-hardness value increased. A similar trend of micro-hardness value of the
composite specimen increases with increases the length of fiber reinforced has been reported
by Bhagat et al. [16].
Density of the composite specimen completely depends on the relative proportion of fiber
reinforcement and matrix. From the table 1. It can be seen that Density of composite increase
with increasing fiber content. On the other hand, as the length is increased from 15mm to 35
Vineet Kumar Bhagat, Anil Kumar Prasad and Arvind Kumar Lal Srivastava
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mm the experimental density of the composite are linearly decreased. This is happen due to
addition of long fiber reinforcement into matrix decrease the packing, which leads to the
disruption of fiber distribution and gives high void. .
Figure 1 Variation on Micro-harness of composites
Table 1 Hardness and density value of coir-luffa hybrid epoxy composite
simple Hardness
(Hv)
Experimental
density(g/cm3)
Theoretical
density(g/cm3)
Void content
(vol. %)
A1 19.45 1.201 1.212 0.945
B2 21.87333 1.193 1.212 1.605
C3 22.29667 1.186 1.212 2.182
D4 25.31667 1.184 1.212 2.328
E5 26.51667 1.174 1.212 3.178 1
1A
22.78333 1.276 1.301 1.887
2
1B 23.61667 1.250 1.301 3.909
3
1C 25.46667 1.242 1.301 4.492
4
1D 30.55 1.222 1.301 6.045
5
1E 32.22333 1.200 1.301 7.753
It is analyzed that when the fiber length increase from 15 mm to 35 mm the volume
fraction of void is found to be increasing and similarly behave as increases fiber content.
Composite at higher fiber loading and length exhibits void. Das et al. [17] was also find the
same trend of volume fraction of void increases with increasing length and content.
The decrease in density is observed with an increase in fiber weight fraction and length of
coir fibers in hybrid composites.
3.2. Effect of fiber length and fiber content on tensile properties
Tensile strength and tensile modulus of composite are effected by fiber length and fiber
loading which shows in figs. 1 and 2 respectively.
Physical and Mechanical Performance of Luffa-Coir Fiber Reinforced Epoxy Resin Based Hybrid
Composites
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Figure 1 Variation on tensile strength of composites.
They found that fabrication of composites also contributes a big impact on the strength,
significantly. It is envisaged that the tensile strength gradually increases with the increase in
fiber length and reaches to a maximum value of 34.54 MPa at 30 mm fiber length and found a
lower value at a greater length of fiber i.e. 35 mm. generally, fiber length is the important
parameter for short fiber reinforce which effect the properties of the composites. In addition to
holding the fiber reinforced together, matrix has an important function of transferring applied
load to the fiber. In case of small fiber length, tensile strength is les due to the fact that length
may not be sufficient for proper distribution load. On the other hand longer fiber length on
composite, tensile strength decreases. Reduction of strength may be due to the fiber
entanglement studied by Rashed et al.[18].From above, it is concluded that maximum strength
of coir and luffa epoxy based hybrid composites is obtained at the fiber length which have a
value near to 30 mm. They have tested the sample of containing fiber length upto 35 mm and
fiber contents at two values i.e. 20% and 25%.
The experiments results shows that the tensile modulus is gradually increased as fiber
length and its contents is increased due to the proper bonding at the interface between fiber
and the matrix which in turns increase the strength of the specimen. Similar trend is also
observed by Geethama et al. [19].composites specimen with 35 mm fiber length and 25 wt. %
gives higher tensile modulus value 2159.34 MPa. Biswas et al.[10] was investigate the tensile
modulus of short coir fiber epoxy resin composite was 2064 MPa of 30 wt.% fiber loading
and at 30 mm fiber length .Mohammed et al.[20] analyzed that the tensile modulus of oil-
palm fiber reinforced epoxy composites was 1342 MPa at 30 wt.% of fiber content.
Vineet Kumar Bhagat, Anil Kumar Prasad and Arvind Kumar Lal Srivastava
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Figure 2 Variation on tensile Modulus of composites
3.3. Effect of fiber length and fiber content of flexural properties
Fig 3. and fig 4. Shows that the variation in flexural strength and modulus of the composites
with effect of length and content of coir-luffa fiber was obtained experimentally from the
three point bend test. It is interesting to seen that flexural strength increases with increasing in
fiber length up to 30 mm and thereafter it decrease. This is happened due to curling behavior
of fiber or longer fiber tend to ball up resulting in low workability and decline in strength.
Similar trend is also happen in tensile behavior. Zuraida et al.[21] was observed same trend on
the study of fiber length variation on coir fiber cement-albumen composites.
Fig 4. Depict the effect of fiber length and fiber content on flexural modulus of luffa-coir
based composite specimen. From current observation we can say that the as the fiber length
increases the flexural modulus also increase irrespective of fiber content. This is happened
due to the proper adhesion between fiber and matrix. On other hand as increasing fiber length
30 mm to 35 mm the flexural modulus is decreasing when further increase the length this is
happened due to the curling nature of fiber which is unable to transfer the load in between
fiber and matrix. Maximum flexural modulus 1092.62 MPa is obtained for specimen with 25
wt. % fiber content and 35 mm fiber length. Hill et al. [22] exibit the same trend of flexural
modulus on the analysis of effect of fiber treatment on mechanical properties of coir or oil
palm fiber reinforced polyester composites.
Physical and Mechanical Performance of Luffa-Coir Fiber Reinforced Epoxy Resin Based Hybrid
Composites
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Figure 3 Effect of fiber content and fiber length on Flexural strength of composites.
Figure 4 Variation on Flexural modulus of composites
3.4. Effect of fiber length and fiber content on impact strength
The impact properties of a materials is its capacity to absorb and dissipate energy under
impact or shock loading. The impact failure of a composite occur by factors like matrix
fracture, fiber/matrix debonding and fiber pull out. It is show that the resistance of impact
loading coir-luffa fiber reinforced epoxy composite improve with gradually increasing fiber
length as show in fig.5. the reason are that the fiber is capable of absorbing energy which
remove the void content in the composites because of appreciative mix up fiber and matrix.
Fig 5. Also show that the increase in impact strength with the increase in fiber content due to
interfacial bonding between fiber and matrix. The same trend was investigated by Biswas et
al. [10].
Vineet Kumar Bhagat, Anil Kumar Prasad and Arvind Kumar Lal Srivastava
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Figure 5 Variation on Impact Strength of composites.
4. CONCLUSION
Current study emphasis the mechanical behaviors of luffa fiber and coir fiber a reinforced
polymer hybrid composites have been analyzed. Following conclusions are drawn from the
present investigation:
• Fabrication of luffa-coir epoxy based hybrid composites are successfully develop by simple
hand lay-up method.
• It has been examine that the void content and hardness of composites are increases with
increasing the both parameter which is fiber length and fiber content. On the other hand
density are decreased with increasing fiber length and content.
• Maximum strength behavior is identified for composite with 25 wt. % fiber content at length
of 30mm.the maximum flexural strength of 60.13 Mpa is observed for composites with the
same composition as earlier. It can be observed that with the increasing of fiber length, the
tensile modulus increases irrespective of fiber loading. Similarly, the maximum hardness
value of 30.55 Hv is obtained for composite with 25 wt. % content at 30 mm fiber length. It is
observed form the figure that maximum impact strength 31.74 kJ/m2 is found at 35 mm fiber
length and 25 wt.% of fiber content.
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