Analysis of mechanical properties of jute fiber strengthened epoxy/polyester composites

Abstract

In recent years, efforts have been made to produce advanced composite materials in order to lessen environmental impact and to extent sustainability. Traditional materials are largely substituted by composites due to their greater properties like flexural strength, low thermal expansion and high strength. Numerous studies are present that show the process of composite materials reinforcement with natural fiber to improve mechanical and thermal properties. The vital aspect of exploitation of natural fiber in composites is associated with biodegradability. An extensive range of different natural fibers has been used for reinforcement till now. In present work, mechanical properties of jute fiber reinforced epoxy and polyester composites manufactured using Taguchi optimization method are investigated, experimentally. It was found that jute reinforced epoxy composite had better mechanical properties than jute polyester composite. Also, Epoxy-jute composite had lower erosion wear rate than polyester jute composites.

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* Corresponding author.
E-mail addresses: kapilmittal007@gmail.com (K. Mittal)
© 2017 Growing Science Ltd. All rights reserved.
doi: 10.5267/j.esm.2017.3.002
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Engineering Solid Mechanics (2017) 103-112
Contents lists available at GrowingScience
Engineering Solid Mechanics
homepage: www.GrowingScience.com/esm
Analysis of mechanical properties of jute fiber strengthened epoxy/polyester
composites
Prabhakar Kaushika , Jaivirb, and Kapil Mittalc*
aAssociate Professor, Department of Mechanical Engineering,UIET, Maharshi Dayanand University, Rohtak, Rohtak, Haryana, India, 124001
bM.Tech Research Scholar, Department of Mechanical Engineering,UIET, Maharshi Dayanand University, Rohtak, Haryana, India, 124001
cAssistant Professor, Department of Mechanical Engineering, FET, Gurukul Kangri University, Haridwar, Uttarakhand, India, 249404
A R T I C L EI N F O A B S T R A C T
Article history:
Received 6 October, 2016
Accepted 3 March 2017
Available online
3 March 2017
In recent years, efforts have been made to produce advanced composite materials in order to
lessen environmental impact and to extent sustainability. Traditional materials are largely
substituted by composites due to their greater properties like flexural strength, low thermal
expansion and high strength. Numerous studies are present that show the process of composite
materials reinforcement with natural fiber to improve mechanical and thermal properties. The
vital aspect of exploitation of natural fiber in composites is associated with biodegradability.
An extensive range of different natural fibers has been used for reinforcement till now. In
present work, mechanical properties of jute fiber reinforced epoxy and polyester composites
manufactured using Taguchi optimization method are investigated, experimentally. It was
found that jute reinforced epoxy composite had better mechanical properties than jute polyester
composite. Also, Epoxy- jute composite had lower erosion wear rate than polyester jute
composites.
© 2017 Growing Science Ltd. All rights reserved.
Keywords:
Jute fiber
Epoxy resin
Polyester resin
Experimental study
Taguchi method
1. Introduction
In the history of materials, one of the most significant achievement is the evolution of composite
materials and their manufacturing processes. Composite materials are used in different areas, where
specific physical and mechanical properties are required. Composites have better impact strength,
tensile strength, and flexural strength as compared to conventional materials (Verma, 2009). Due to
these advantages, these are broadly used in the aerospace, automotive and infrastructure industries.
Composite materials are produced by mixing two or more materials containing different properties and
generally consist of a tougher and lighter material (Chow et al., 2007). The stronger or tougher material
is known as reinforcement and lighter material is known as a matrix. Main function of matrix is to
transfer stress between reinforced fibers and protect the composite from mechanical damage.
Reinforcement in the composite improves the mechanical properties like flexural strength, impact

104
strength, tensile strength, and stiffness (Chandramohan & Marimuthu, 2011). Based on the matrix
material used, composites are of three type metal matrix composites, ceramic matrix composites and
polymer matrix composites (Dhanasekran & Balachandran, 2008). Each type has its definite
applications. Further, in metal matrix composites, metals are used for matrix material (Girisha et al.,
2014). Another term ‘Ceramics’ are known as inorganic and non- metallic materials that have utility in
our daily lifestyle. In ceramic matrix composites, ceramic is taken as matrix material. Ceramic material
contains inorganic material such as plates, pottery, bricks, glass, titles, oxides, nitrides, carbides of
silicon, zirconium, aluminum, etc. (Khan et al., 2016). When polymer resins are used as matrix material
with any type of reinforcement agent such as composite material, these are called as polymer matrix
composites. This type of composites is mostly used because of ease of fabrication, lower cost, and good
electrical & thermal insulator and lower density (Gujjala et al., 2014). The property of such composite
material depends on three elements. These are: (i)Type of Polymer, (ii) Reinforcement Material and
(iii) Filler Material or Interface. Polymer matrix composite are considered to be the most significant
class of composite as compared with metal matrix and ceramics matrix (Onal & Adanur, 2002). These
matrices are easily fabricated and have low cost. This type of matrix is classified in to two types:
Thermosets polymers and Thermoplastic polymers. Thermosets polymers are most effective type of
matrix system. In this, resins undergo polymerization and cross linking during curing process. These
polymers do not melt on reheating, but they decompose thermally at high temperature. Examples of
thermosets are unsaturated polyesters, epoxies, polyimides and vinyl esters. Composites (especially
those made of natural fibers), due to their unique advantages have numerous application in todays’
technically advancing environment (Pujari et al., 2014; Kumar et al. 2004; Mansourian et al., 2016;
Kumar, 2016). In this paper, specimen of an Epoxy/Polyester composite consisting jute fibers has been
prepared and an analysis of their mechanical properties have been made by performing certain tests.
2. Materials & experimental details
2.1 Materials
For the preparation of the specimen, jute fiber is used, as reinforcement material and epoxy\polyester
are the matrix materials. Epoxy and polyester resins are supplied by ‘Saakshi dye and chemicals, New
Delhi’. The density of epoxy and polyester at room temperature are 1.16 and 1.09, respectively. Woven
jute fibers were collected from local sources (Fig. 1).
Fig. 1. Woven Jute Fiber
2.2. Composite Fabrication
To prepare the matrix material for composite, epoxy resin, polyester resin, hardener, and accelerator
are used. The epoxy resin and corresponding hardener (HY951) were mixed in a weight ratio of 10:1.
Hand lay-up technique was used for the preparation of composite. A mould having dimensions
150×30×7mm was prepared. Then jute fiber in the form of woven was reinforced with epoxy and
polyester separately in different weight proportions (11%, 22%, 33%, 44%, and 55%) to prepare
composites. Jute fiber is laid in the mould uniformly and compressed. Then the fiber seat was removed
and remover was applied to the mould. The jute fiber was kept again in mould. Resin and respective
hardener were mixed separately and uniformly poured over the compressed fiber. Then the mixture

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was compressed again and left for a curing period of 24 hours. After completion of the curing process,
samples were cut to required size as per ASTM standards. The composite samples of five different
composition EJ-1 to EJ-5 which have an epoxy resin as matrix material and five other composite
samples PJ-1 to PJ-5 which have polyester as matrix material were prepared. The composition of
prepared samples is shown in Table 1.
Table 1. Composition of prepared samples
Sample Composition
EJ-1 Epoxy + jute (11% by volume)
EJ-2 Epoxy + jute (22% by volume)
EJ-3 Epoxy + jute (33% by volume)
EJ-4 Epoxy + jute (44 % by volume)
EJ-5 Epoxy + jute (55% by volume)
PJ-1 Polyester + jute (11% by volume)
PJ-2 Polyester + jute (22% by volume)
PJ-3 Polyester + jute (33% by volume)
PJ-4 Polyester + jute (44 % by volume)
PJ-5 Polyester + jute (55% by volume)
2.3 Mechanical Testing
After preparation of specimen, the samples were subjected to different mechanical testing according
to ASTM standards. For each composition, five specimens were tested to evaluate the mechanical
properties, so that statistically significant results were obtained.
1) Flexural Test
Flexural test was performed on the specimen by using a universal testing machine. Flexural strength
is the ability of a material to bend before the breaking point. The test is conducted at a constant speed
of 2.38mm/min at room temperature. Dimensions of specimen for the flexural test were 150×30×7 mm3
and standard followed was ASTM 790-03. The specimen was placed between two supports of span
length 100 mm.
2) Impact Test
This test was performed on the Izod impact-testing machine. The specimen was clamped upright in
an anvil. A striker carried on pendulum, which is allowed to fall freely from a fixed height, then hits
the test specimen. The specimens were tested as per ASTM-D 256-05 standard. The dimension of the
specimen for impact test was 64×15×7 mm3.
3) Erosion testing of composite specimen:
Erosion test rig as per ASTM G76 was used for the erosion testing of the composite specimen. The
erosion test rig basically consists of an air compressor, air filter, air drying unit, hopper, mixing
chamber and a vibrator which is basically connected to mixing chamber. The erodent particles basically
consists of silica sand. With the help of the conveyer belt these sand particle were brought to the mixing
chamber where the compress air was mixed and the mixture was allowed to pass through the converging
brass nozzle of 3 mm internal diameter.
3. Taguchi experimental design
For robust design, Taguchi experimental design was used. It is a very simple and organized approach
through which the design parameters can be optimized while reducing the overall testing time and
experimental cost (Kaushik et al., 2016). It consists of two important tools. These tools are:
 Signal to noise ratio: - It extent quality which accentuate on variation.

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 Orthogonal Array: - It holds all the design parameters at the same time.
The selection of the design parameters is a very important stage in the design of experiment.
Through entire literature reconsideration of the polymer composite in case of erosion behavior, it was
conformed that parameters like filler content, impact velocity, Stand off distance, Impingent angle,
erodent temperature etc. affect the erosion rate of composite. For sophisticated planning of experiments
Taguchi approach for four factors and three levels was used. In the Taguchi approach the array which
was to be chosen was L₉ (3⁴). In relation to the test it contained four columns at three levels. In the
present study out of all parameters only four parameters were taken. All the four parameters were
considered at each three levels. The experimental observations were converted into signal to noise ratio.
Depending upon the type of characteristics, signal to noise ratios are of several types:
Smaller-the-better characteristic:
S/N= -10log 1/n {Ʃp²}, (1)
Nominal-the-better characteristic:
S/N= -10log {ƩP/ X²}, (2)
Larger-the-better characteristic:
S/N= -10log 1/n {Ʃ1/p²}, (3)
where n is the number of observation, p is data observed, P is the mean and X is the variance. Under
the smaller the better, the S/N ratio was minimum for erosion rate, which can be calculated from Eq.
(1). Whole scheme is elaborated in Tables (2-4).
Table 2. Parameters set for erosion test
Control factor Symbols Fixed parameters
Impact Velocity Factor A Erodent Silica sand
Impingent Angle Factor B Nozzle Diameter 3 mm
Erodent Size Factor C Stand Off Distance 100 mm
Fiber Loading Factor D Length Of Nozzle 80 mm
Table 3. Control factors for each level
Control factor Level Units
1 2 3
Impact Velocity 35 45 55 m/sec
Impingent Angle 30 60 90 Degree
Erodent Size 300 400 500 µm
Fiber Loading 22 33 44 % by volume
Table 4. Orthogonal arrays for L₉ Taguchi design
SR. No A B C D
1 1 1 1 1
2 1 2 2 2
3 1 3 3 3
4 2 1 2 3
5 2 2 3 1
6 2 3 1 2
7 3 1 3 2
8 3 2 2 3
9 3 3 1 1

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4. Results and discussion
The specimens were tested for their flexural and impact strength and following results were
obtained.
4.1 Flexural Test
Table 5 gives the values of flexural strength of a specimen with different fiber loading for jute-
reinforced epoxy/polyester composites.
Table 5. Flexural strength of composite specimen
Sam
p
le Value in n/mm²
EJ-1 25.31
EJ-2 32.47
EJ-3 36.45
EJ-4 47.67
EJ-5 33.84
PJ-1 12.77
PJ-2 14.71
PJ-3 17.03
PJ-4 20.23
PJ-5 19.91
Fig. 2 shows the flexural strength of jute polyester composite. Flexural strength increases up to 44
% of fiber loading and then start decreasing with further increase in fiber loading. It was also observed
that at 11% composite shows lower impact strength. The maximum flexural strength obtained is 20.23
N/mm2 and minimum value obtained for flexural strength is 12.77 N/mm2 with 11% fiber loading.
Fig. 2. Flexural Strength of Jute Polyester Composite
The flexural strength of jute-reinforced epoxy composites is shown in Fig. 3. For jute-epoxy
composite the maximum value of flexural strength came out to be 47.67 N/mm2 obtained at 44% fiber
volume fraction and minimum value was 25.31 N/mm2 obtained at 11%. The impact strength increases
up to 44% of fiber loading and after that starts decreasing as the fiber content increases.
Fig. 3. Flexural Strength of Jute-Epoxy Composite
0
5
10
15
20
25
11 22 33 44 55
Flexuralstrength
fiberloading(vol%)
0
10
20
30
40
50
60
11 22 33 44 55
Flexuralstrength
fiberloading(vol%)

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Fig. 4 shows the comparison of flexural strength between jute reinforced epoxy and polyester
composites. Jute reinforced epoxy composite have more flexural strength as compared to jute-polyester
composite. For jute-epoxy composite, the flexural strength was 35.14 N/mm2 and for jute-polyester
composite was 16.93 N/mm2.
Fig. 4. Comparison between Flexural Strength of Jute Reinforced Epoxy/Polyester Composite
4.2 Impact Test
Table 6 shows the values of impact strength for different specimens. Fig. 5 shows the results of impact
strength of jute reinforced polyester composites. From the values obtained, it was observed that at 44%
of fiber loading maximum value of impact strength was achieved. Moreover, with an increase in the
fiber loading impact strength increases up to 44% fiber content. A further increase in the fiber loading
relatively decreased the impact strength. The minimum value of impact strength was 81.74 J/m2
observed at 11% fiber loading and maximum strength was 148.58 J/m2 at 44 % fiber loading.
Table 6. Impact strength of different specimens
Sample Value in j/m
EJ-1 20.39
EJ-2 46.55
EJ-3 73.33
EJ-4 110.74
EJ-5 99.42
PJ-1 81.74
PJ-2 108.54
PJ-3 132.83
PJ-4 148.58
PJ-5 119.7
Fig. 5. Impact Strength of Jute-Polyester Composite
Similarly, in case of jute-epoxy composite, impact strength changes with the fiber volume fraction
as shown in Fig. 6. Impact strength of epoxy composite was minimum at 11% fiber loading and
maximum at 44%. A further increase in fiber loading subsequently decreased the impact strength.
0
10
20
30
40
Polyster Epoxy
Flexuralstrength
0
50
100
150
200
11 22 33 44 55
Impactstrength
fiberloading(vol%)

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Fig. 6. Impact Strength of Jute-epoxy Composite
A comparison between the impact strength of jute reinforced epoxy-polyester composites is shown
in Fig. 7 in form of a graph. It explains that polyester based composites have better impact strength as
compared to epoxy-based composites. Impact strength of polyester based composite was 118.28 J/m2
and for epoxy based composite was 70.04 J/m2. It was also observed that for both epoxy and polyester
based composites 44% fiber volume fraction was best to obtain maximum impact strength.
Fig. 7. Comparison between Impacts Strength of Jute Reinforced Epoxy/Polyester Composite
4.3 Erosion Test
Part 1: Jute-Polyester Composites
The analysis of Taguchi experiment was performed using MINITAB 17 software. Using Taguchi
approach and orthogonal array L9 an experiment was designed for all possible combination of control
factors and corresponding levels before measuring the performance of composites. The calculated
erosion rate of jute fiber reinforced polyester composite for 9 different combination over 4 important
factors (discussed earlier in Table 2) is as follows (Table 7):
Table 7. S/N Ratio and Erosion Rate for Jute-Polyester Composite
SR. No A B C D ER S/N RATIO
1 35 30 300 22 196.987 -45.8888
2 35 60 400 33 237.689 -47.5202
3 35 90 500 44 251.231 -48.0015
4 45 30 400 44 264.852 -48.4601
5 45 60 500 22 238.124 -47.5543
6 45 90 300 33 226.481 -47.1006
7 55 30 500 33 267.157 -48.5353
8 55 60 300 44 298.364 -49.4947
9 55 90 400 22 257.743 -48.0536
It is evident from the table that the most significant factor is the impingement angle which is
followed by impact velocity and then fiber loading while the factor erodent size is the least significant
factor in erosion of jute reinforced polyester composite. For the erosion rate the mean of the S/N ratio
is -47.8454 db. The effect of each factor is shown in Fig. 8 and Table 8.
0
20
40
60
80
100
120
11 22 33 44 55
Impactstrength
fiberloading(vol%)
0
50
100
150
Polyster Epoxy
Impactstrength

110
Fig. 8. Effect of Control Factors
Table 8. Response Table for S/N Ratios (smaller is better)
Level A B C D
1 -47.14 -47.63 -47.49 -47.17
2 -47.70 -48.19 -48.01 -47.72
3 -48.69 -47.72 -48.03 -48.65
Delta 1.56 0.56 0.54 1.49
Rank 1 3 4 2
Part 2: Jute Epoxy Composite
The calculated erosion rate of jute epoxy composite for 9 different combinations over 4 important
factors (discussed earlier in Table 2) is as follows (Table 10):
Table 9. S/N ratio and erosion rate for different test conditions
SR. No A B C D ER SN RATIO
1 35 30 300 22 151.810 -43.6260
2 35 60 400 33 166.465 -44.4265
3 35 90 500 44 182.345 -45.2179
4 45 30 400 44 196.765 -45.8790
5 45 60 500 22 172.879 -44.7545
6 45 90 300 33 191.463 -45.6417
7 55 30 500 33 204.879 -46.2299
8 55 60 300 44 227.980 -47.1579
9 55 90 400 22 198.678 -45.9630
From Table 9 it is clear that the most significant factor among all the factors is the impact velocity
which is followed by fiber content and then impingement angle while the factor erodent size is the least
significant factor in erosion of jute reinforced epoxy composite. For the erosion rate the mean of the
S/N ratio is -47.8454 db. The effect of each factor is as shown in Fig. 9 and Table 10.
Fig. 9. Effects of Control Factors
321
-47.0
-47.2
-47.4
-47.6
-47.8
-48.0
-48.2
-48.4
-48.6
-48.8
321 321 321
A
Mean of S N ratios
B C D
Main E ffects Plo t for SN ratios
Data Means
Signal-to-noise: Smaller is better
321
-44.5
-45.0
-45.5
-46.0
-46.5
321 321 321
A
Mean of SN ratios
B C D
Main Effects Plot for SN ratios
Data Means
Signal-to-noise: Smaller is better

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Table 10. Response table for S/N ratios (smaller is better)
Level A B C D
1 -44.42 -45.24 -45.48 -44.78
2 -45.43 -45.45 -45.42 -45.43
3 -46.45 -45.61 -45.40 -46.08
Delta 2.03 0.36 0.07 1.30
Rank 1 3 4 2
5. Conclusions
In current work, experiments were carried out to find the flexural and impact strength of jute
reinforced epoxy and polyester composites for different fiber loadings. The following conclusions
could be obtained from the experimental results.
1. The flexural and impact properties of jute fiber reinforced epoxy and polyester composite have been
considerably enhanced with the various fiber volume fractions.
2. It was found that with the increase in the fiber volume fraction, flexural strength also increases.
Maximum flexural strength was achieved at 44 % volume fraction of fiber for both jute reinforced
epoxy and polyester composites.
3. Impact strength increased with an increase in the fiber volume fraction and was maximum at 44 %.
Overall, it was obtained that at 44% volume fraction of the jute fiber composite showed the
maximum mechanical properties.
4. Maximum flexural strength obtained for jute-reinforced epoxy composite was 47.67 N/mm2, while
for jute reinforced polyester composite it was 20.23 N/mm2. Thus jute reinforced epoxy composite
have better flexural strength as compared to jute reinforced polyester composites.
5. Maximum impact strength obtained for jute-reinforced epoxy composite was 110.74 J/m2. While
for jute-reinforced polyester composite it is 148.58 J/m2. So jute-reinforced polyester has better
impact strength.
6. The results obtained by this research indicate that jute reinforced epoxy composite have better
mechanical properties than jute polyester composite.
7. Erosion behaviors of composite have been successfully analyzed by Taguchi experimental design.
Significant control factors affecting the erosion rate have been identified through this technique.
8. Results showed that impact velocity is highly influencing control factor for erosion rate. After that
fiber loading and impingent angle are most contributing factors. Least influencing control factor
for erosion rate is erodent size.
9. Epoxy- jute composite have lower erosion wear rate than polyester jute composites.
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