Experimental analysis of jute fiber and polyurethane composite
Abstract— Natural fiber reinforced composites (NFRCs) are increasingly used in a variety of
commercial applications, but there has been little theoretical, micromechanical modeling of
structure/property relationships in these materials. Many of our modern technologies demand
materials with unusual combination of properties such as high strength to weight ratio, high
stiffness, high corrosion resistance, high fatigue strength, high dimensional stability etc. These
can’t be met by conventional metal alloys. The scope of possible uses of natural fibers is
enormous.
Plenty of research work is done on natural fiber composites. But, woven jute fiber and bio based
polyurethane resin matrix is not used for research studies. Literature review shows that
composite made of combination of these constituents is not studied in order to know its
properties. The present paper focus is on the experimental analysis and testing of untreated
woven jute fiber and PUR composite. The tensile properties of natural fiber reinforced
composites (NFRCs) are modeled using mathematical model. Mathematical model is used to
investigate and predict the properties and fibre loads effect on mechanical properties. The
combination of jute fibre with PU produced the material that is competitive to synthetic
composites.
Keywords— Jute Fiber, NFRC, PUR, Tensile strength
I. INTRODUCTION
Biocomposite is the composite having natural fiber and bio based resin matrix as its
constituents. One of the limitations of biocomposites is the difficulty to predict the mechanical
behavior due to the interface conditions between the natural fibers and the polymeric matrices.
The elastic and tensile properties of NFRC can be experimentally determined or derived from a
variety of mathematical models.
In some cases, fiber aspect ratio, fiber volume fraction and fiber orientation are also included.
In the present work, PU resin and woven jute fiber composite is subjected to experimental
analysis. This paper outlines some of the recent reports published in literature on mechanical
behavior of natural fiber based polymer composites with special emphasis on woven fiber
reinforced polymer composites.
The mechanical properties of a natural fiber-reinforced composite depend on many parameters,
such as fiber strength, modulus, fiber content ,fiber length and orientation, in addition to the
fiber-matrix interfacial bond strength. A strong fiber-matrix interface bond is critical for high
mechanical properties of composites. A good interfacial bond is required for effective stress
transfer from the matrix to the fiber whereby maximum utilization of the fiber strength in the
composite is achieved. Modification to the fiber also improves resistance to moisture induced
degradation of the interface and the composite properties. In addition, factors like processing
conditions/techniques have significant influence on the mechanical properties of fiber reinforced
composites. Mechanical properties of natural fibers, especially flax, hemp, jute and sisal, are
very good and may compete with glass fiber in specific strength and modulus. A number of
investigations have been conducted on several types of natural fibers such as kenaf, hemp, flax,
bamboo, and jute to study the effect of these fibers on the mechanical properties of composite
materials.
Vasanta V Cholachagudda, Udayakumar P A, Ramalingaiah, presented ”Mechanical
characterisation of Coir and rice husk reinforced Hybrid polymer composite’’[1]. They have
chosen coir fiber as the major reinforcement and rice husk as an additional fiber to improve the
mechanical property of polymer composite with vinyl ester as the base material prepared by hand
layup process according to ASTM standards.
Test specimens are prepared with different weight fractions of coir fiber at the optimization
point of tensile test a small percentage of rice husks are added and tests were conducted and the
improvement in mechanical properties
Avtar Singh et al. [2]. Performed a Study of Mechanical Properties of Hybrid Natural Fiber
Composite. Samples of several Jute-Bagasse-Epoxy & Jute-Lantana camara-Epoxy hybrids were
manufactured using hand layup method were kept at 40%-60%. With increase of fiber loading
capacity by 20%, the flexural strength value increases to 155.5MPa for Jute-bagasse and
310.9MPa for jute-lantana camara. The tensile strength of epoxy is 62-72 MPa wit 3-4 %
elongation and with increase of fiber loading capacity by 20 % the tensile strength increases.
Dixit S. and Verma P [3]. Studied The Effect of Hybridization on Mechanical Behavior of
Coir/Sisal/Jute Fibers Reinforced Polyester Composite Material. Coir and jute reinforced
polyester composite (CJRP), jute and sisal reinforced polyester composite (JSRP) were evaluated
experimentally. The tensile and flexural properties of hybrid composites are markedly improved
as compare to unhybrid composites. Water absorption behavior indicated that hybrid composites
offer better resistance to water absorption.
M. Porfiri and N. Gupta, [4] presented a paper on effect of volume fraction and wall thickness
on the elastic properties of hollow particle filled composites and developed a modeling scheme
to estimate elastic constant. Fiber content is the chosen parameter which affects the tensile
properties of composite.
M. Mohamed, S. Anandan, Z. Huo, V. Birman, J. Volz, K. Chandrashekhara [5] evaluated
stiffness load carrying capacity of composite with thermoset polyurethane resin system as a
matrix.
MATERIALS AND PROCESSING
A. Materials
The materials used in the present research work are tabulated in TABLE I with their properties.
Materials
Jute Fiber
Polyurethane Resin (Urecast 70)
Hardener PU
Specifications
Fiber density:1.46 g/cc
Single fiber length:120-150 mm
Tensile strength: 393-800 MPa
Density: 1.300  0.500 g/cc
Viscosity at 27oC : 5000  500
mPa.s
Curing time for Optimum
properties : 6 hrs at RT and post
cure at 80-90 o C – 4 hrs or 4-5
days at RT
Flexural strength: 360-370 kg/
cm2
E Modulus: 4500 N / mm2
Impact strength notched : 2.6-3.0
kg/ cm2
Deflection at Break: 4.0
Adhesive Strength: 155 kg /cm2
Density: 1.220  0.100 g/cc
Viscosity: 300  100 mPa.s
TABLE I Specifications of the Materials Used in the Research
B. Processing of Woven jute/Polyurethane Composite.
First make some sample preparation calculation before preparing the woven jute fiber and PUR
composite. Firstly Mould releasing agent is applied on inner surface of both mould plates. A rectangular
mould of size 600x150x3mm is used for manufacturing of composite laminate. The calculated amount of
resin with thoroughly mixed promoters, accelerators and hardener (PU resin: PU Hardener, 100:25 % by
weight) and after 5-10 minutes it is made ready for pouring into mould with fibers. Resin is applied by
using brush on the lower plate of mould. Woven fiber layer is then kept over resin layer. As per thickness
required, number of layers is evaluated and alternatively fiber layers and resin are arranged.
At last upper mould plate is kept over lower one and pressure is applied by fixed using C-clamps and
bolts. It is then heated in a furnace at 600 for an hour.
The setup for 24 hours to complete cure the laminate and once the laminate is completely cured then it’s
ready for machining according to ASTM standard for testing, repeat the procedure by adding 32, 44, 50,
55% wt of jute fiber to the resin.
Fig. 1 Composite laminate prepared using Hand layup process
C. Sample Preparation
Composite laminate of 150 mm X 300 mm X 3 mm were fabricated according to ASTM standards for mechanical
tests.
1) Density of PU (δ) = 1.35 g/cm3
2) Volume of the mold (V) = 600x150x3mm
=270000 mm3
= 270 cm3
3) Mass of resin (m) =Volume of mould x Density of PUR
= cm3 x g/cm3
= 364.5g ≈ 365g.
Samples
% wt of Jute
A
B
C
D
E
F
G
0
30
42
48
51
53
54
% of PUR
resin
Matrix
100
70
58
42
49
47
46
Mass of jute
fiber (g)
Mass of PUR
resin (g)
Total Mass (g)
0
75
105
120
127.5
132.5
135
250
175
140
125
122.5
117.5
115
250
250
250
250
250
250
250
TABLE II Samples Preparation Calculation for Woven Jute/PUR Composite
The above samples are tested for mechanical properties that are tensile strength and tensile modulus (Modulus of
elasticity, Young’s Modulus) according ASTM standards.
III. MECHANICAL CHARACTERISATION
Composite materials were subjected to various mechanical tests to measure strength, elastic constants,
and other material properties. The results of such tests were used for two primary purposes: 1)
engineering design (for example, failure theories based on strength, or deflections based on elastic
constants and component geometry) and 2) quality control either by the materials producer to verify the
process or by the end user to confirm the material specifications.
A Universal Testing Machine (UTM) is an instrument used for the measurement of loads and the
associated test specimen deflections such as those encountered in tensile, compression or flexural modes.
It is used to test the tensile properties of materials (constituent and composite). Load cells and
extensometers measure the key parameters of force and deformation as the samples were tested. The
Universal Testing Machine set up is shown in Fig.2 (a)
1) Ultimate tensile strength =
Maximum load in N
in MPa.…………………….…… (1)
C/s area
2) Young’s modulus (E) = Stress in GPa……….……………………………..…….……… (2)
Strain
3) Stress (σ) =
Load (l )
in N/mm2… ………………………………………………… (3)
Area(b  d )
4) Strain = change in length / Original length…………………………………………………(4)
C/s area in mm2
P = maximum load in N, b = width of the specimen in mm, d = thickness of the specimen in mm
B. Tensile Test Report
TABLE IV Tensile Strength of Woven Jute / Polyurethane Composite
Samples
A
B
C
D
E
F
% wt of Jute
fiber
30
42
48
51
53
54
TS in MPa
18.545 21.383
33.025 33.29
33.71 36.52
53.52 66.585
69.043 78.727
82.1
87.11
Avg TS in
MPa
19.964
33.1575
35.115
60.0525
73.885
84.605
Fig.3 (a) Variation of UTS with jute fiber loading
Fig.2 Universal Testing Machine. (a) Universal testing machine set up and loaded tensile test specimens.
A. Ultimate Tensile Strength
Ultimate tensile strength, often referred to tensile strength is the maximum stress that a material can
withstand while being stretched or pulled before fracture. The tensile test for the specimens was
conducted according to ASTM
D 638-03.
The specimens of size 200 mm x19 mm x 3mm were tested with a span length of 200 mm in tensile mode
at a cross head speed of 10 mm / min. Instantaneous values for load, deflection, stress and strain were
gathered and plotted using software. The specimen used for the tensile testing, UTM gripper and strain
gauge extensometer is shown in Fig. 2(b)
Strain Gauge
Gripper
Fig.2 (b)-Strain gauge mounted on specimen
B. Tensile Test Report
Fig.3.2-Single fiber test
Sr.
No
Sample
Tensile Strength
Identification
(MPa)
1
No.1
79.16
2
No.2
98.04
3
No.3
78.82
TABLE V Ultimate Tensile Strength Of Single Jute fiber
CONCLUSION
 The conclusion of the study of woven jute fiber and PUR composite is that there is significant
increase in the tensile strength of the composite.
 Tensile strength of the composite increases but there is a variation in rate of rise of tensile strength
and modulus (in tension) with increase in fiber loading.
1. With the addition of woven jute the tensile strength increases from 19.964 MPa at 32% fiber
loading
and there is sudden rise at 44% jute fiber. Tensile strength for this fiber content is 33.157 MPa.
2. There is a gradual rise in tensile strength Up to 50% of fiber loading.
3. There is a sudden rise in tensile strength at 53%. After 53% (up to 56%) slope of curve seems to remain
constant.
4. It is observed from the curve that from rate of change of tensile strength from 32% to 50% is is greater
than that of from 53% to 56%.
 Theoretically (as per mathematical models) slope for tensile property vs. Vf plot remains constant.
Conclusion From experimental test results1. From 30-40% of Vf slope is constant and curve is seemed to be linear.
2. Rate of increase of tensile strength is lesser from 30-40% than that of from 48-51%
3. From 51-54% tensile strength is showing rapid rate of rise in value.
4. Tensile modulus curve is having constant slope for initial modulus values (i.e.-from 30-42% Vf)
evaluated experimentally.
5. From Vf-42-50% rate of change of modulus slightly decreases.
6. From 50-54% rate of change of tensile modulus increases
ACKNOWLEDGMENT
I am thankful to the Department of Mechanical Engineering staff and also Prof. A.V. Salve , VIIT
institute of technology, Prof. Y.S. Munde , Cummins college of engineering and co-author Mr. Sagar
Kulkarni for their support to carry out this research work.
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