DAFFODIL INTERNATIONAL UNIVERSITY JOURNAL OF SCIENCE AND TECHNOLOGY, VOLUME 11, ISSUE 1, JANUARY 2016
67
STUDY AND CHARACTERIZATION OF RICE HUSK ASH WITH
POLYESTER RESIN COMPOSITE
Md. Mahfujul Islam1, Humayun Kabir2,
Farid Ahmed3, Md. Abdul Gafur4
1
Daffodil International University, Bangladesh
Department of Physics, Jahangirnagar University, Bangladesh
4
Pilot Plant & Process Development Center of Bangladesh Council of
Scientific& Industrial Research (BCSIR), Bangladesh
2&3
E-mail: mahfujul.ns@diu.edu.bd
Abstract: Rice husk ash (RHA) reinforced polyester
composites containing 5% to 20% rice husk ash with
respect to the weight of unsaturated polyester resin
have been prepared by compression molding.
Different physical and mechanical properties such as
water absorption, compressive strength, elastic
modulus, flexural strength, hardness of rice husk ash
composites were investigated by standard methods.
Universal testing machine (UTM), Leebrebound
hardness tester, Vickers hardness tester were used to
characterize the Rice husk ash polyester composites.
The effects of amount of rice husk ash in rice husk ash
polyester composite on different mechanical and
thermal properties of rice husk ash composites were
studied in detail. The results indicated that amount of
reinforcing agent plays a vital role in the properties
of rice husk ash composites.
Keywords: Rice husk ash, polyester resin,bulk
density, flexure strength and elastic deformation.
1. Introduction
Advance science and technology spread out all
over the world and due to the Expansion of
population it’s the time to concern about the
dimensional use of materials. Our resource is
being expansion and our planet is being polluted.
We need such material which is friendly to the
environment. The environmental awareness
throughout the world is encouraging scientific
research into the development of cheaper, more
sustainable, environmental friendly construction
and packing materials. From the ancient era
human civilization is quite familiar with a kind
of material named as composite material.
Composite materials include any products made
from a blend of two or more base material, and
Date of submission : 09.06.2015 Date of acceptance : 04.04.2016
this unique material which remain separate and
more distinctive from the beginning one.
Accordingto the University of Delaware's Center
for Composite Materials, ‘By mixing multiple
materials together, manufacturers can combine
the best properties of each base component’.
Composite materials typically offer enhanced
strength or durability over many other products
and may provide additional benefit like
resistance to moisture or corrosion. Some
examples of composite materials include fiber
cement, thermoplastics or composite wood
products.
A unique feature of composites is that the
characteristics of the finished product can be
tailored to a specific engineering requirement by
the careful selection of matrix and the
reinforcement type. For examples aircraft
engineers are increasingly searching for
structural materials that have low densities, are
strong, abrasion and impact resistant, and are not
easily corroded. Frequently, strong materials are
relatively dense, increasing the strength or
stiffness generally results in a decrease in impact
strength [1-4].Nature is full of examples wherein
the idea of composite materials is used. The
coconut palm leaf, for example, is nothing but a
cantilever using the concept of fiber
reinforcement. Wood is a fibrous composite;
cellulose fibers in a lignin matrix. The cellulose
fibers have high tensile strength but are very
flexible (i.e. low stiffness), while the lignin
matrix joins the fibers and furnishes the stiffness.
Bone is yet another example of a natural
composite that supports the weight of
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STUDY AND C HARACTERIZATION OF R ICE HUSK ASH WITH Polyester Resin Composite
variousmembers of the body [5].Composites are
combination of two materials in which one of the
materials, called the reinforcing phase, is in the
form of fibers, sheets, or particles, and are
embedded in the other materials called the matrix
phase. The reinforcing materials and the matrix
material can be metal, ceramic, or polymer.
Typically reinforcing materials are strong with
low densities while the matrix is usually a
ductile, or tough, material. If the composite is
designed and fabricated correctly, it combines
the strength of the reinforcement with toughness
of the matrix to achieve a combination of
desirable properties not available in any single
conventional material. Examples of some current
application of composites include the brakeshoes, submarine, satellite, civil infrastructures,
pads, tires and the diesel piston aircraft in which
100% of the structural components are
composites [6].Recently many types of natural
fibers have been investigated for use in plastics
including rice husk, jute, straw, wood, wheat,
barley, oats, rye, bamboo, sugarcane, grass,
reeds, ramie, sisal, coir, banana, papyrus etc.
Natural fibers have many significant advantages
over synthetic fibers. The primaryadvantages of
natural lignocellulose fiber reinforcement in
polymer
composite
materials
are,
its
biodegradable, abundantly available, easily
decomposable in the environment and ecofriendly[7].In the Research we used natural fiber
named as rice husk ash as reinforcement
material with polyester resin. And made the rice
husk ash reinforced polyester resin composite.
Basically rice husk ash produced from rice husk.
Generally rice milling industry generates a lot of
rice husk during milling of paddy which comes
from the fields. This rice husk is mostly used as
a fuel in the boilers for processing of paddy. Rice
husk is also used as a fuel for power generation.
Rice husk ash (RHA) is about 25% by weight of
rice husk when burnt in boilers. During milling
of paddy about 78 % of weight is received as
rice, broken rice and bran .Rest 22 % of the
weight of paddy is received as husk. This husk is
used as fuel in the rice mills togenerate steam for
the parboiling process. This husk contains about
75 % organic volatile matter and the balance 25
% of the weight of this husk is converted into ash
during the firing process, which is known as rice
husk ash (RHA). This RHA in turn contains
around 85 % - 90 % amorphous silica [8, 9].. And
rice husk ash was obtained by firing rice husk at
different temperatures (400, 500, 7000c). RHA is
a carbon neutral green product. Lots of ways are
being thought of for disposing RHA through
making commercial use of the RHA.The main
objective of this research work is to achieve a
composite with better mechanical properties
using rice husk ash fiber as reinforcement with
polyester resin as a polymer matrix.
2. Materials and methods
2.1 Raw materials
2.2 Required equipment’s for sample
preparation
Raw materials that have been used in this
research work were polyester resin, rice husk ash
and Methyl ethyl ketone per oxide as hardener.
The equipment’s that have been used were oven,
open mold, close mold, Paul-Otto Weber press
machine, Universal testing machine, electric
balance etc.
2.3 Preparation of Composite
Different percentages ofrice husk ash and
polyester resin were taken to prepare composite.
Rice husk ash was taken from 0 to 20% by wt.
The Table-1 shows different percentages of
samples. A bowl was taken to mix up the raw
materials of the composite. Definite amount of
various percentages of rice husk ash &polyester
resin has been weighed in the bowl and then raw
materials were mixed very carefully with a stirrer
for about 15 minutes. Ethyl methyl ketone
peroxide was used as a hardener, as an amount of
2% wt of polyester resin. The mixer was then
poured into the closed and open mold and was
kept it for 4-5 hours for drying. After drying the
composite was released from the mold with
Paul-Otto Weber Press Machine by applying
pressure. Polyethylene sheet was used to
smoothing the sides of the composite.
DAFFODIL INTERNATIONAL UNIVERSITY JOURNAL OF SCIENCE AND TECHNOLOGY, VOLUME 11, ISSUE 1, JANUARY 2016
Table 1 Rice husk/Ash polyester resin composite
Composite
APC-1
APC-2
APC-3
APC-4
APC-5
Rice husk
ash (%)
0
5
10
15
20
Polyester resin
(%)
100
95
90
85
80
69
3. 1 Bulk Density
The mass density or density of a material is
defined as its mass per unit volume. In some
cases (for instance, in the United States oil and
gas industry), density is also defined as its
weight per unit volume, although, this quantity is
more properly called specific weight. Bulk
density specimen was prepared according to the
ASTM C135 [10].
2.4 Characterization
Various mechanical properties such as tensile
strength, elongation at break, tensile modulus,
bending strength and bending modulus of the
prepared composites were studied by Universal
Testing Machine (model 1011UK, INSTRON
Corporation) system.
D=
…………………………………................,,,.......(1)
Where D is the density, Wsthe weight and V the
volume of the specimen.
The bulk density effect of variation of wt. % of rice
husk ash on the bulk density of rice husk ash
reinforced polyester composites were investigated and
shown in Fig.1.
3. Result and discussion
Figure 1: Effect of amount of rice husk ash on density of rice husk ash/polyester composite.
Varying the amount of matrix, rice husk ash and
polyester is the most important parameter of this
fabricated process. A number of percentages by
WT rice husk ash (0%, 5%, 10%, 15%, and
20%)
have been taken for fabrication. The
density of rice husk ash and polyester
composites decreases with the increase of the
amount of rice husk ash. Thus the bulk density
decreases from 0.00118 gm. /cc to 0.0010 gm./cc
when the amount of rice husk ash increases from
0 to 20wt. %.
3.2 Water Intake
The effect of immersion time on water
absorption of Rice husk ash/Polyester
composites prepared with different wt. % (0%,
5%, 10%,15% and 20%) of rice husk ash is
shown in Fig. 2. It reveals that the water
absorption depends on rice husk ash content and
immersion of time. Water absorption depends on
the time and amount of materials. Result shows
that the water absorption increased with
increasing rice husk ash .The rate of water
absorption is very low with time. This is due to
the fact that reduction in the cured polyester and
the degree of cross-linking reaction, which
diminishes the void spaces i.e. with the increase
of molding load, the composite becomes more
dense or reinforced materials are distributed
properly eliminating all voids [11].Mineral fillers
are hydrophobic in nature (the incapability of
filler to absorb water is known to be hydrophobic
filler). This is because of hydrophobic nature of
rice husk ashhas a very small amount of water
intakes in the composites[12].
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STUDY
AND C HARACTERIZATION
OF R VOLUME
ICE HUSK 11,
ASHISSUE
WITH1,
Polyester
Resin
DAFFODIL INTERNATIONAL UNIVERSITY JOURNAL
OF SCIENCE
AND TECHNOLOGY,
JANUARY
2016Composite
Figure 2: Effect of soaking time on water absorption property of rice husk ash/polyester composite.
3.3 Flexure Strength
Flexure strength is also known as bending
strength or rapture strength. The flexural strength
of a material is defined as its ability to resist
deformation under load. Flexural specimen was
prepared according to ASTM D790M, 3 point
loading [13]. The strength may be calculated for
any point of the load deflection by means of the
following equation,
S=
……………………………... (2)
Where, S = stress in the outer fibers at mid-span,
MPa, P = load at a given point on the load–
deflection curve, N, L=support span, mm, B=
width of specimen tested, mm, D = depth of
tested specimen, mm.
The flexural test was carried out by using
universal testing machine or UTM (model
1011UK,
INSTRONCorporation).In
this
experiment, the support span length was 45mm
and the test speed was 5 mm/min.
Fig. 3 illustrates the effect of addition of rice
husk ash on Flexural Strength for rice husk
ash/Polyester composite. It reveals that the
Flexural Strength decreases with the addition of
rice husk ash composites. The flexural strength
of the composites is lower than polyester resins,
so these composites are brittle. Ceramic
materials are brittle, hard, and strong in
compression, weak in shearing and tension. It
also shows that the increasing in volume fraction
of rice husk ash (RHA) promotes more interfaces
and cavities formed in the composite and this can
explain the decreasing of flexural strength. The
decrease in strength of RHA polyester
composites on increasing the volume fraction of
RHA is due to RHA being weak in tension.
Figure 3: Effect of variation of amount of rice husk ash on flexural strength of rice husk ash/polyester
composite.
DAFFODIL INTERNATIONAL UNIVERSITY JOURNAL OF SCIENCE AND TECHNOLOGY, VOLUME 11, ISSUE 1, JANUARY 2016
3.4 Elastic Modulus
Elastic (E) Modulus of Rice husk ash/Polyester
composites as a function of the addition of
different rice husk ash percentage are shown in
Fig. 4. It can be found that the E-Modulus of the
composite increased with an increase in rice husk
ash. For more addition of rice husk ash, EModulus decreased. The E-Modulus is a measure
of stiffness of a material. Thus, the stiffness of
rice husk ash/polyester and composite increased
with an increase in rice husk ash until 5% and
then decreases with more addition of rice husk
ash as found in case of 20%.From this graph, it is
clearly observed that the e-modulus increases
71
with fiber content up to 5% then decreases
slightly to a lower value. Again this increment of
elastic modulus may be related to the regular
distribution pattern the fiber and the polymer on
the composites. The decrease of the e-modulus
might be due to the decrease in wet ability of the
matrix to the fibers, where the matrix loses its
ability to wet the fibers at high concentration and
fibers act alone and the matrix cannot transfer
the load between the fibers. Another reason
might be due to poor distribution or dispersion of
fibers within the matrix which is related to the
use of inefficient method of mixing.
Figure 4: Effect of variation of rice husk ash on Elastic modulus of rice husk ash/polyester composite.
Figure 5: Effect of variation of rice husk ash on compressive strength of rice husk ash/polyester composite.
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STUDY AND C HARACTERIZATION OF R ICE HUSK ASH WITH Polyester Resin Composite
3.5 Compressive Strength
Compressive strength is the capacity of a
material or structure to withstand axially directed
pushing forces. When the limit of compressive
strength is reached, materials are crushed. The
compressive strength is usually obtained
experimentally by means of a compressive test.
The apparatus used for this experiment is the
same as that used in a tensile test. The effect of
addition of rice husk ash on compressive
strength for Rice husk ash/Polyester represented
in Fig. 5. Variation of compressive strength of
rice husk ash/polyester composites depends on
the size of particles. Result indicated that
compressive strength of porcelain/polyester
composite decreases with the increase of rice
husk ash[14].
3.6 Vickers Hardness Test
The Vickers hardness (HV) is calculated with an
equation ( ), wherein load (L) is in grams force
and the mean of two diagonals (d) is in
millimeters:
Figure 6: Effect of variation of rice husk ash on Vickers Hardness of rice husk ash/Polyester composite.
Fig. 6 illustrates that Vickers Hardness for Rice
husk ash/Polyester composite as a function of the
addition of different wt. % of rice husk ash. It
can be seen that in this composites, hardness
decrease with an increase of rice husk ash. And it
shows that rice husk ash composite is softer than
pure sample of the polyester composite.
3.7 Leeb Rebound Hardness Test
Fig. 7 shows the effect of addition of rice husk
ash on Rebound Hardness of rice husk
ash/Polyester composite. Results indicated that
Rebound Hardness of rice husk ash/polyester
composite decreased with the increase of rice
husk ash,it measures the hardness of sample
material and harden material produce a higher
rebound velocity than softer material. The
stiffness of the composites are high (Higher EModulus) but the stiffness of rice husk
ash/polyester composite is lower than pure
sample composites and as a result, rice husk
ash/polyester composites is softer than pure
polyester composites.
Figure 7: Effect of addition of rice husk ash on Rebound Hardness of rice husk ash/Polyester composite.
DAFFODIL INTERNATIONAL UNIVERSITY JOURNAL OF SCIENCE AND TECHNOLOGY, VOLUME 11, ISSUE 1, JANUARY 2016
4. Conclusion
The bulk density of rice husk ash/Polyester
composites decreasevery slowly with an increase
in the amount of rice husk ash content. For all
the composites water absorption increases with
increase of fiber addition and soaking time.
Flexural strength of rice husk ash/Polyester
composites decrease constantly with an increase
of rice husk ash content. But the modulus of rice
husk ash/composite increase with the addition of
rice husk ash constantly and after 15% modulus
suddenly decreases. The flexural strength was
lower than polyester resin, so these composites
are more brittle. The compressive strength
decrease with an increase of the amount of rice
husk ash and it is found that e-modulus increased
at the beginning of the addition of rice husk ash
but it suddenly decrease on the addition of 10%
and 15% of rice husk ash. Hardness of the
composite decrease with an increase in the
addition of rice husk ash content due to elastic
deformation.
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