M. ANNAMALAI, R. RAMASUBBU: OPTIMIZING THE FORMULATION OF E-GLASS FIBER AND COTTON ...
207–214
OPTIMIZING THE FORMULATION OF E-GLASS FIBER AND
COTTON SHELL PARTICLES HYBRID COMPOSITES FOR THEIR
MECHANICAL BEHAVIOR BY MIXTURE DESIGN ANALYSIS
OPTIMIRANJE OBLIKOVANJA HIBRIDNEGA KOMPOZITA Z
E-STEKLENIMI VLAKNI IN DELCI BOMBA@NIH LU[^IN –
ANALIZA MEHANSKIH LASTNOSTI ME[ANIC
Manikandan Annamalai1, Rajkumar Ramasubbu2
1Unnamalai Institute of Technology, 628502 Kovilpatti, Tamilnadu, India
2Mepco Schlenk Engineering College, 626005 Sivakasi, Tamilnadu, India
amanik1968@yahoo.co.in
Prejem rokopisa – received: 2017-07-15; sprejem za objavo – accepted for publication: 2017-10-02
doi:10.17222/mit.2017.119
The purpose of this work is to create and examine the mechanical properties of an eco-friendly, low-cost natural fiber filled with
glass-fiber-reinforced polymer composite. Cotton shell (CS) particles are a less expensive natural fiber material that can be used
as filler, integrated with glass fiber in epoxy-resin matrices. By keeping the optimized resin weight as a constant (75 % of mass
fractions), six composites C1, C2, C3, C4, C5 and C6 of different weight percentages of glass fiber and the CS filler were
prepared and the corresponding mechanical properties were examined as per ASTM standards. The glass fiber of 15 % of mass
fractions and filler material of 10 % of mass fractions of the composite "C3" shows the best mechanical properties. The mixture
design analysis is used to evaluate the results obtained mathematically, and the predicted values confirm that the 10 % of mass
fractions of addition of CS particles with the glass fiber augment the mechanical properties of the hybrid composites. The
chemical composition of the cotton shell particles was analyzed by using energy-dispersive spectroscopy (EDS). Also, the
surface morphology of the raw CS particles and the fractured surfaces of the tested specimens were examined with a scanning
electron microscope (SEM).
Keywords: E-glass fiber, cotton shell (CS) particles, epoxy resin, mechanical properties, mixture design analysis
Namen tega dela je bil oblikovati in preiskati mehanske lastnosti cenenega, ekolo{ko prijaznega polimernega kompozita iz
naravnih vlaken ter oja~anega s steklenimi vlakni. Delci bomba`nih lupinic (angl. CS) so cenen vir naravnih vlaken, ki se lahko
uporabi kot polnilo in s steklenimi vlakni integrira v epoksidno matrico. Avtorji ~lanka so v tej raziskavi obdr`ali konstantni
masni dele` epoksidne smole (75 mas. %) v {estih me{anicah C1,C2,C3,C4,C5 in C6 z razli~nimi masnimi dele`i steklenih
vlaken in CS polnila. Pripravljene kompozite so mehansko okarakterizirali v skladu z ASTM standardom. Kompozit C3 s 15
mas. % steklenih vlaken in 10 mas. % CS polnila je imel najbolj{e mehanske lastnosti. Da bi matemati~no ovrednotili dobljene
rezultate so avtorji uporabili t.i. MDA (angl.: Mixture Design Analysis) in napovedane vrednosti analize so potrdile, da dodatek
10 mas. % CS delcev k steklenim vlaknom, izbolj{a mehanske lastnosti hibridnih kompozitov. Kemijsko sestavo bomba`nih
lupinic so analizirali z energijskim dispezijskim spektrometrom (EDS). Prav tako so povr{insko morfologijo CS delcev in
prelomne povr{ine preiskovanih vzorcev pregledali z vrsti~nim elektronskim mikroskopom (SEM).
Klju~ne besede: E-steklena vlakna, delci bomba`nih lu{~in, epoksidna smola, mehanske lastnosti, analiza oblikovanih me{anic
1 INTRODUCTION
Natural fibers demonstrate predominant mechanical
properties, for example, adaptability, firmness and mo-
dulus, compared with glass filaments. Currently, the
popular natural filaments sisal and jute fibers are
supplanting the glass and carbon fibers owing to their
simple accessibility and cost. Polymers and their compo-
sites are being more and more employed because of their
superior strengths and low densities. On account of their
outstanding properties, fiber-reinforced polymer compo-
sites are used chiefly in the automotive and aircraft
industries, spacecraft and ships. The accumulation of a
particular filler diminishes the polymerization shrinkage
of the radically polymerizing resin, enhances the dimen-
sional stability, amplifies the elastic modulus and
strength to the level found in dental tissues, decreases the
friction wear and produces a better X-ray opacity.1 The
composite industry always seeks for an alternative low-
cost source that can reduce the overall manufacturing
costs and boost the stiffness of the materials. Natural
materials have noteworthy advantages, which give a
reason for their use. Other than their environmental
profit, the probable benefits of natural fibers are, the
plentiful accessibility of the raw materials from renew-
able resources, rather than fossil sources, and their lower
cost. Also, they have an elevated specific strength due to
their lower density. In addition, it is possible to achieve
an elevated loading of natural fibers in reinforced plastic
composites than in traditional inorganic fillers, since the
former is a softer nonabrasive material.2
The majority of developing countries are very rich in
agricultural fiber and a big fraction of agricultural waste
is being utilized as a fuel. Only India produces more than
400 million tones of agricultural waste yearly. Growing
Materiali in tehnologije / Materials and technology 52 (2018) 2, 207–214 207
UDK 67.017:677.521:677.21.08:620.1 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 52(2)207(2018)
concern about global warming, mainly due to defores-
tation, has led to the growth of new materials to replace
wood, which improves most favorable consumption of
natural resources. Presently, natural fibers form a sub-
stitute for glass fiber, the most extensively applied fiber
in composite technology. The positives of the natural
fibers over synthetic fibers like aramid, carbon or glass
fiber are low densities, non abrasive, non-toxic, high
filling levels, possibly resulting in a high stiffness and
specific properties, biodegradable, low cost, good ther-
mal and acoustic properties, good calorific value and
superior energy recuperation. The environmental impact
is reduced as the natural fiber can be thermally recycled
and fibers come from a renewable resource. The natural
fibers also put forward the possibility in developing
countries to make use of their own natural resources in
their composite processing industries.3 Utilizing the
easily obtainable lower cost fillers, we can advance the
properties and reduce the overall cost of components.4
Natural fibers having cellulose, hemi cellulose and
lignin are being examined for the appropriateness of
alternating synthetic fibers. The utilization of these
natural fillers has been due to its monetary benefit during
processing, high specific strength, comparatively low
density and the bio-degradability, thereby reducing the
environmental contamination.5 The idea of adding parti-
cles of sub-micro- or nano-scale into polymers is one of
the most fascinating subjects in the current decades.6
One of the methods to augment the mechanical proper-
ties of fiber-reinforced polymer (FRP) composites is to
progress the properties of the epoxy matrix by inte-
grating second-phase modifiers into the resin. Owing to
their high specific strength and stiffness, FRP compo-
sites are broadly used in ship hull, airframe, and wind-
turbine structural applications. When polymerized, the
epoxy becomes amorphous and it is an extremely cross
connected material. This microstructure of the epoxy
polymer leads to many valuable properties such as a high
modulus and failure strength, low creep, etc., but also
directs to an adverse property in that it is moderately
brittle and has reasonably poor resistance to crack
instigation and propagation.7
The FRP composite material consists of a polymer
that acts as a matrix and a reinforcing material, which is
chosen as per preferred applications and properties. In a
typical FRP composite, the fiber performs as a typical
load-carrying aspirant, while the matrix transmits the
load to the fiber and to guard it from any fault. Exten-
sively used glass-fiber reinforcing material has its out-
standing corrosion resistance, weight reduction, high
impact, superior tensile strength and little cost. In
general, it is used with polymer matrices such as epoxy
resin, vinyl ester, isophthalic polyester resin and unsatu-
rated polyester resin.8 Polymers are reinforced with
fibers and fillers to get better mechanical and tribological
properties and to achieve a better strength-to-weight
ratio. Various types of non-metallic bearing materials
currently exist commercially. Polymeric bearing mate-
rials are used exclusively where fluid lubricants are
ineffective due to the aggressive environmental condi-
tions, complexity to afford maintenance also due to
product and environmental pollutions.9 Currently, unam-
biguous fillers/additives are supplementary to improve
and amend the superiority of composites as these are
found to impart a key role in formatting the physical pro-
perties and mechanical performance of the composites.10
In the past two decades, the lignocellulosic natural
fibers are being commonly used as reinforcements and
fillers in polymer applications.11 The mechanical proper-
ties are mainly influenced by the particle size, shape and
specific surface area of integrated particles/fillers in
polymers.12 Hybridization that is reinforced with more
than one fiber, is one of the best ways to defeat the
limitations of the mechanical properties of the polymer
composites.13 Because of these combined properties of
high strength and stiffness-to-weight ratio, corrosion
resistance, excellent damping character and resilience,
the hybrid composites are broadly used in industrial
applications.14 For the making of interior and exterior
components of automotives, natural fiber mats are wide-
ly used.15 The essential applications of these composites
M. ANNAMALAI, R. RAMASUBBU: OPTIMIZING THE FORMULATION OF E-GLASS FIBER AND COTTON ...
208 Materiali in tehnologije / Materials and technology 52 (2018) 2, 207–214
Figure 2: Cotton shell powderFigure 1: Cotton shell
are developing quickly in most of the engineering areas,
particularly where the cost of the material is a major
criterion and to make better the erosive environment.16
Nano-sized or micro-sized particles reinforced
composites ended in agglomeration, which causes stress
concentration, which ultimately reduces the potency of
closely packed samples.17 Composite materials afford
design engineers with advanced quality and extended life
period. Superior strength, lower weight with fewer
maintenance have directed to numerous engineering
applications.18
The objective of this paper is to learn the perspectives
of using ligno-cellulosic plant remainder as a filler for a
thermoset polymer. These plant residues are a low-priced
by-product, eco-friendly and practically sustainable raw
materials. The size of the particles ranging from 125 μm
to 149 μm, and shape of the CS particles progress the
uniform distribution of the filler particles in the matrix
materials of the FRP composites. The CS particles have
less density and can be considered as suitable filler
materials for the development of lightweight and high-
strength composites.
Hence, in this present work, a first attempt is made to
study the mechanical properties of CS particles inte-
grated into glass-fiber reinforced polymer composites by
varying the addition of particles content. Also, the mix-
ture design analysis is carried out to identify the optimal
formulation of glass fiber and CS particles.
2 EXPERIMENTAL PART
2.1 Materials
Cotton Shell (CS) was produced from a local village
in Kovilpatti, Tamilnadu, India. The density is 1.2726
g/cm3. Araldite LY 556 is medium viscosity, unmodified
liquid epoxy resin based on Bisphenol –A and Aradur
HY 951 is a low viscosity, unmodified, aliphatic poly-
amine, were supplied by Javanthee enterprises, Guindy,
Chennai, India. The specific gravity of the resin is
1.15–1.20 g/cm3 whereas the hardener is 0.97–0.99
g/cm3. The Chopped strand mat (CSM) E-Glass fiber of
300 GSM was purchased from Goa Glass fibers Ltd.,
Goa, India, and its specific gravity is about 2.6 g/cm3.
The resin and the hardener are mixed with a ratio of
100:10 by weight, as recommended, and they are mixed
uniformly until they form a homogeneous mixture.
Initially, the CS was dried in the sun for a week and
then washed thoroughly with distilled water to remove
the residual dirt and impurities and then dried again in
the sun for one week. The dried CS was ground to fine
powder using a ball milling machine and a set of stan-
dard sieves are arranged in descending order of fineness
and shaken for 20 min and the size in the range of
125 μm to 149 μm particles are used for this research
work. The CS and CS powders are seen in Figure 1 and
2, respectively.
2.2 Methods
The percentages of glass fiber and resin were opti-
mized by mixture design analysis.19 The resin/glass
fiber/CS composites were developed by mixing opti-
mized constant 75 % of mass fractions of epoxy resin
with different % combinations of glass fiber and CS
filler content. The formulation of the different compo-
sites is given in the Table 1.
A thin coating of hard wax was applied over the
mould cavity for easy removal of prepared composite.
Measured amounts of epoxy and hardener were mixed in
a container and stirred well using a mechanical stirrer,
then a measured quantity of CS filler is added and again
stirred well for a particular time and then the mixture is
poured in the mould cavity and the Chopped Strand Mat
(CSM) E-Glass fiber of measured quantity is placed in
between the resin and filler layers so that the required
thickness is achieved. Finally, the composite laminates of
size of 250 mm × 250 mm × 3 mm were fabricated by
hand lay-up technique followed by compression
moulding.
Six different composites of various glass fiber and
filler contents by weight were prepared. After that, for
better curing of the composite, it was kept under pressure
of about 7 MPa for 4 h to 6 h in the hydraulic press, at
room temperature. The suitable dimensions of specimen
were prepared according to the size and shape as per
ASTM Standards, using a diamond cutter. The sample
tensile specimens are shown in Figure 3.
Tensile, compression and flexural tests were done
using a universal testing machine manufactured by ABS
Instrumentation Pvt. Ltd., with the capacity of 40 T and
accuracy of 1 N with a cross head speed of 5 mm per
minute, as per the standards ASTM D 638, ASTM D 695
and ASTM D 790, respectively.
The hardness test was conducted by using the Barcol
hardness tester as per the standard ASTM D 2583 also
the impact test is conducted as per ASTM D 256 stan-
dard, using impact testing machine manufactured by
Fuel Instruments and Engineers (FIE) Pvt. Ltd., For all
the tests, four samples were tested and the average value
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Materiali in tehnologije / Materials and technology 52 (2018) 2, 207–214 209
Figure 3: Tensile specimens for different composites
was taken into consideration. The values are exhibited in
Table 2.
Table 1: Composition of cotton shell particles integrated fiber
reinforced polymer
Sl. No: Composite Resin % Glass fiber%
CS particles
%
1 C1 75 25 00
2 C2 75 20 05
3 C3 75 15 10
4 C4 75 10 15
5 C5 75 05 20
6 C6 75 00 25
3 RESULT AND DISCUSSION
3.1 Mechanical properties
The tensile specimens of six different GFRP compo-
sites with filler were tested and the values were plotted
on the Y axis against the various weight % of glass fiber
and filler material in the X axis. The tensile strength
values elevate from composite C1 to C3 and thereafter it
starts descending in its values, as seen in the Figure 4.
That is, up to addition 15 % of mass fractions of CS
fillers, the tensile strength values increases and further
addition of filler particles leads to decrement of tensile
strength value. Hence, it is conclusive that the composite
C3 has highest tensile strength value and is better when
compared to the other combinations.
Similarly, the corresponding other test values are
plotted in the Y axis against the various weight % of
glass fiber and filler material in the X axis. The respec-
tive graph Figures 5 to 8, reveals that the mechanical
properties are increasing from C1 to C3 and falls down
after crossing C3. From this, it is confirmed that the
mechanical properties of C3 are dominative and found
better with the composition of 15 % of mass fractions of
glass fiber and 10 % of mass fractions of CS filler.
3.2 Scanning electron microscopy (SEM) analysis
Morphological studies using a scanning electron
microscope (Carl Ziess EVO 18, Kalasalingam Univer-
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210 Materiali in tehnologije / Materials and technology 52 (2018) 2, 207–214
Table 2: Mechanical properties of different composites
Sl. No: Composite Tensile strength(MPa)
Compressive
strength (MPa)
Flexural strength
(MPa)
Hardness
(HB)
Impact energy
(J)
1 C1 50.62 85.79 100.2 38 5
2 C2 55.1 99.83 112.3 40 6
3 C3 71.8 115.2 123.8 44 8
4 C4 57.3 105.4 103 41 6
5 C5 40.6 90.7 80.1 36 4
6 C6 20.45 84.9 66.7 34 3
Figure 5: Compressive strength of FRP for different % of mass
fractions of glass fiber and CS filler
Figure 4: Tensile strength of FRP for different % of mass fractions of
glass fiber and CS filler
Figure 6: Flexural strength of FRP for different % of mass fractions
of glass fiber and CS filler
sity, Krishnankoil, Tamilnadu, India), evidently illustrate
the GFRP composites (Figures 9a to 9f). The Figure 9a
shows the morphology of the composite with only glass
fiber of 25 % of mass fractions. Morphology of the
GFRP composites with the filler addition starts from 5 %
of mass fractions to 20 % of mass fractions are exhibited
in the Figures 9b to 9e. And micrograph in Figure 9f
shows the composite with only CS fillers of 25 % of
mass fractions.
The micrographs noticeably point out that while the
CS particles were supplemented with GFR epoxy matrix,
there is a change in the occurrence of the microstructure.
The microstructure of the GFR epoxy matrix disclosed
that there is a presence of amorphous structure with ex-
tended boundaries.
It was noticed that the glass fibers are protected by
the layer of matrix and there is a fine diffusion of CS
fillers with the matrix (Figures 9b to 9c). The appro-
priate combination of the CS fillers – epoxy matrix has a
significant role in the developed GFRP composites.
Sturdy filler – epoxy matrix of interlinked bonding with
glass fiber is important for better mechanical properties
of the composites. When the CS particles contribution
exceeds 10 % of mass fractions there is a non-uniform
distribution of the particles in the matrix and poor
interfacial bonding between the epoxy, glass fiber and
CS fillers, which leads to the formation of delamination
and pull out of the fiber and fillers, which leads to the
descending values of the mechanical properties.
3.3 Density
The density of a composite depends on the relative
proportion of the matrix and reinforcing materials and
this is the most significant factor influencing the pro-
perties of the composites. The theoretical and measured
densities along with the respective volume fraction of
voids were exhibited in Table 3. The composite density
values calculated theoretically from weight fractions are
not in concurrence with the experimentally found values.
The disparity between these two is a measure of voids
and pores present in the prepared composites. The
volume fraction of voids kept on changing as the filler
content addition changes for different composites.
The presence of voids considerably affects the me-
chanical properties and performance of the composites in
the position of utilization. More voids generally means
less fatigue resistance and more susceptibility to water
penetration. The awareness of void content is advan-
tageous in assessing the excellence of the composites. It
is logical that a superior composite must have fewer
voids. However, the existence of a void is obvious to
some extent in composite preparation.
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Materiali in tehnologije / Materials and technology 52 (2018) 2, 207–214 211
Figure 9: SEM: a) of glass fiber with 25 % of mass fractions, b) of
20 % of mass fractions glass fiber with 5 % of mass fractions of CS
filler, c) of 15 % of mass fractions glass fiber with 10 % of mass
fractions of CS filler, d) of 10 % of mass fractions glass fiber with
15 % of mass fractions of CS filler, e) of 5 % of mass fractions glass
fiber with 20 % of mass fractions of CS filler, f) of 25 % of mass
fractions of CS filler
Figure 8: Impact energy of composites for different % of mass frac-
tions of glass fiber and CS filler
Figure 7: Hardness of composites for different % of mass fractions of
glass fiber and CS filler
Table 3: Theoretical and measured density of the composites with vol-
ume fraction of voids
Sl. No: Composite
Theoretical
density
g/cm3
Measured
density
g/cm3
Volume
fraction of
voids (%)
1 C1 1.362 1.34 1.62
2 C2 1.325 1.30 1.89
3 C3 1.291 1.26 2.4
4 C4 1.254 1.21 3.51
5 C5 1.228 1.17 4.72
6 C6 1.198 1.12 6.51
4 OPTIMIZATION BY GLASS FIBER AND CS
FILLERS BY MIXTURE DESIGN ANALYSIS
In order to forecast the output response correspond-
ing to the input parameters, here the mathematical
modeling tool Mixture Design Analysis is used. The
response is the function of the properties of the various
components in the mixture. The mechanical properties of
the CS fillers integrated GFRP composite specimens
such as tensile strength (TS), compressive strength (CS),
flexural strength (FS), hardness (HS) and impact energy
(IE) are assigned as response functions. The glass fiber
and CS filler are the components in the mixture. With the
help of the arrived numerical expressions for the res-
ponses, the magnitude of the response can be established
for any value of the input parameter. Then the predicted
responses can be compared with the experimental values.
The degree of the nearness of the predicted and experi-
mental response value will exhibit the accuracy of the
model for the specific experiment. Design Expert 9 soft-
ware is used for the simple lattice mixture modeling. The
design methodology can be extended for the mixture
with 2-30 constituents. A simple lattice mixture design
of degree m consists of m + 1 points of evenly spaced
values between 0 and 1 for each component. For
example, if m = 2 then the possible fractions are 0, 1/3, 1
and if m = 3 then the probable values are 0, 1/3, 2/3, 1.
To obtain the optimal formulation of the GFRP com-
posites by forecasting the best possible composition of
glass fiber and CS filler. The experimental results were
analyzed by using mixture design analysis in order to
attain an empirical model for the outstanding response.
The modeling tool is arrived as linear, quadratic and
cubic form of equations for the response functions.
Using the mathematical equations represented as coded
factors are in the Table 4, the mechanical properties TS,
CS, FS, HS and IE for the various combinations of glass
fiber and CS filler can be designed precisely.
The design expert works out the numerical optimiza-
tion on an objective function designated as Desirability.
The altogether desirability (D) is the geometric mean of
all individual desirabilities (di ) that ranges from zero to
one, as given in Equation (1):
D d d d d n
n= × × × ×( ) /1 2 3
1
 (1)
where n is the total number of responses. If any one of
the responses beyond its desirability range, the overall
function will become zero. For betterment of result, by
assigning the highest response as the optimization
parameter, the numerical optimization is worked out for
the response functions.
By putting together the individual desirability values
in to a whole single number and then look for the maxi-
mum overall desirability. After the analysis, here it is the
overall desirability is 0.803 which is nearer to 1, which is
the ideal value.
In Figure 10, the ramp report is displayed in which
the individual response graph is given for a better under-
standing. The red dot corresponds to the component level
in the specific mixture. The blue dot corresponds to the
response level for the specific component levels in the
mixture. The dot on every ramp represents the response
prediction for that solution. The altitude of the dot indi-
cates how desirable it is.
A bar graph showing the individual responses desir-
ability and overall desirability is also obtained from the
analysis. The overall desirability function D evolved as
0.803498, in which di varies between zero and one as per
the proximity of response to its ideal value. The desir-
ability values that are 1 and nearer to 1 are stated as
excellent. In this the red bar represents the different
M. ANNAMALAI, R. RAMASUBBU: OPTIMIZING THE FORMULATION OF E-GLASS FIBER AND COTTON ...
212 Materiali in tehnologije / Materials and technology 52 (2018) 2, 207–214
Figure 10: Ramps report of numerical optimization of glass fiber and
filler particles
Table 4: Mathematical model for mechanical properties of glass fiber with filler
Response Sl. No Response Model Numeric equation
R1 TS Cubic TS A B A B= × + × + × ×48 95 1911 114 62. . .
R2 CS Cubic CS A B A B= × + × + × ×86 88 80 93 97 98. . .
R3 FS Cubic FS A B A B= × + × + × ×102 25 61 55 118 35. . .
R4 HS Cubic HS A B A B= × + × + × ×38 33 25
R5 IE Cubic IS A B A B= × + × + × ×5 07 2 50 11 61. . .
components in the mixture and the blue bar represents
the responses of GFRP with CS filler. The desirability of
all the five responses lie between zero and one, which
indicates that all the responses are well within the
agreeable limits, which is shown in the Figure 11.
In the Table 5, the end results of the analysis of
variance (ANOVA) for the mechanical properties are
exhibited, which clearly specify that the predictability of
the model is at 95 percent confidence interval.
The predicted response fits well with those of the
experimentally obtained responses. And also it is con-
firmed from the Table 6, that all the predicted values of
the responses lie in the range between 95 % PI low and
95 % PI high.
Table 5: Response prediction for glass fiber with filler
Two sided
component Name
Confidence = 95 % n = 1 Coding
Level Lowlevel
High
level
A Glassfiber 14.99 0.00 25 Actual
B Filler 10.01 0.00 25 Actual
Total = 25
Table 6: Summary of the prediction for the responses
Response Prediction Std. dev SE (n=1) 95 % PIlow
95 % PI
high
TS 64.519 5.93736 6.95 42.39 86.65
CS 108.021 6.41165 7.51 84.12 131.92
FS 114.371 8.23169 9.64 83.69 145.05
HS 42 1.82574 2.14 35.20 48.80
IE 6.82848 0.941124 1.10 3.32 10.34
5 CONCLUSIONS
Based on the investigations, for developing new
polymer composites, the cotton shell particles could be
recognized as potential low-cost natural fibers filled with
glass fiber.
As per the test results, the mechanical properties are
showing their better values for the composite "C3" that is
glass fiber of 15 % of mass fractions and CS fillers of
10 % of mass fractions, when compared to the other
combinations. It is evident that after the 10 % of mass
fractions, further addition of CS filler leads to a decrease
in mechanical properties.
The surface morphology study of the fractured
surfaces is carried out by SEM, which discloses that the
CS fillers have appreciable interaction with the matrices
up to 10 % of mass fractions addition, but further if the
addition of filler exceeds there is poor bonding between
them and the formation of cracks and voids occur. From
the study, thus concluded that CS filler integrated GFRP
composites with 15 % of mass fractions of glass fibers
and 10 % of mass fractions of filler have better mecha-
nical properties.
The mixture design analysis is implemented to reveal
the predicted values for various responses. On the whole,
the desirability for GFRP with CS filler is 0.803. This
shows that the desirability value is nearer to 1 and good.
From the numerical optimization it is established that
10 % of mass fractions CS filler in GFRP exhibits the
best results.
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