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JMRTEC-448; No. of Pages 10
ARTICLE IN PRESS
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Available online at www.sciencedirect.com
www.jmrt.com.br
Original Article
Physical and mechanical properties of sugar
palm/glass fiber reinforced thermoplastic
polyurethane hybrid composites
Atiqah Afzaluddin a , Mohammad Jawaid a,∗ , Mohd Sapuan Salit a,b ,
Mohamed Ridwan Ishak c
a
Laboratory of Biocomposite Technology, Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia, Serdang
43400, Selangor, Malaysia
b Department of Mechanical Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
c Department of Aerospace Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
a r t i c l e
i n f o
a b s t r a c t
Article history:
This paper studied the physical and mechanical properties of sugar palm and glass fiber rein-
Received 14 January 2018
forced thermoplastic polyurethane hybrid composites with the aim of investigation on the
Accepted 17 April 2018
hybrid effects of the composites made of natural and synthetic fibers. The aim of this study
Available online xxx
is to evaluate the physical properties such as density, thickness swelling, water absorp-
Keywords:
composites were also investigated. Morphological properties of tensile fracture samples of
tion whereas the tensile, flexural and impact properties of sugar palm, hybrid and glass
Sugar palm fibers
composites were done by using scanning electron microscopy (SEM). The composites were
Thermoplastic polyurethane
fabricated at a constant weight fraction of total fiber loading at 40 wt.% using melt com-
Glass fibers
pounding method. The result revealed that incorporation of glass fiber 30 wt.% to sugar
Hybrid composites
palm/TPU composites exhibited the higher density, lower thickness swelling and water
Physical properties
absorption properties. The tensile and impact properties of the hybrid composites were
Mechanical properties
improved with the increasing of sugar palm fiber content (30/10 SP/G) as compared to glass
fiber reinforced composites (0/40 SP/G) due to the excellent hybrid performance of the two
fibers. The flexural properties were increased when the higher amount of glass fiber was
introduced at 40 wt.% (0/40 SP/G). The fibers cracks, fiber pull out and fiber dislocation of
the fractured surfaces are evaluated by using scanning electron microscope (SEM). Overall
results indicated that the incorporation of glass fiber to sugar palm fiber composites can
improve the physical and mechanical properties and developed hybrid composites can be
used as an alternate material for glass fiber reinforced polymer composites for different
applications.
© 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier
Editora Ltda. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
∗
Corresponding author.
E-mail: jawaid md@yahoo.co.in (M. Jawaid).
https://doi.org/10.1016/j.jmrt.2018.04.024
2238-7854/© 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda. This is an open access
article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article in press as: Afzaluddin A, et al. Physical and mechanical properties of sugar palm/glass fiber reinforced thermoplastic
polyurethane hybrid composites. J Mater Res Technol. 2018. https://doi.org/10.1016/j.jmrt.2018.04.024
JMRTEC-448; No. of Pages 10
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1.
Introduction
As a matter of fact, composite is comprised of more than one
basic material with constant dissimilar properties. This combination, however, at micro’s level has not merge together and,
hence can be identified either as reinforcement or matrix. As
to its fibers, natural fibers or synthetic fibers have become
significant material as a reinforcement to produce the fiber
reinforced polymer (FRP) composite.
In recent development of FRP, natural fibers are dominating the demand and application from industry in which it was
before, highly depending on synthetic fibers. This migration
from synthetic fibers to natural fibers is began from the view
that natural fibers are efficient in term of cost, density, easy-toget, eco-friendly, non-toxic, flexible, renewable, biodegradable,
abrasive less, high strength and modulus, and easy to process.
However, be that as it may, there are some identified drawbacks of natural fibers which is low strength in impact part
and high water uptake in absorption properties part.
Apart from FRP, thermoplastic composites are equally competitive in dominating the demand and application from
industry due to its remarkable properties, amongst, excellent
strength and very firm when in load proportion, recyclability, good corrosion resistant and ecological resistant [1]. The
efficiency of this thermoplastic is best elected when it can
overcome the situation where the intrinsic brittleness of thermosetting matrices happened in certain low temperature’s
condition [1,2]. As mentioned, this is the excellent factor in
the thermoplastic where it can sustain the lower temperature in the product operation in which the thermosetting has
reach its limit, and in the case of thermoplastic polyurethanes
(TPUs), for instance, this matrices is able to be combine and
process with high elasticity of elastomers and even have glass
transition temperature lower than −40 ◦ C.
In probing the way out from those weaknesses, hybridization technique is identified as an urgently required invention to improve the mechanical properties. Basically, this
hybridization technique is purported to combine a single fiber
with additional fibers to strengthen the mechanical properties
as opposed to one fiber in the composites. This combination of
multiple fibers as mentioned, has equally distributed the loading and stress imposed from matrix to fibers and successively
can increase the mechanical properties.
The fact that natural fibers is well-known in lower cost
and lighter weight, its mechanical properties is being compromised too when its mechanical properties were tested to be
lower as compared to the mechanical properties in glass fibers.
At this weak point, the outcome from hybridization to synthetic and natural fibers, called as hybrid synthetic and natural
fibers have shown that this low mechanical property can be
improved. Studies have been conducted to see the effect from
load proportion aspect and it was found that hybrid synthetic
and natural fibers’ result are encouraging the mechanical
properties to its good loading performance. Hybridization of
glass fiber with other viable natural fibers like kenaf [3,4], jute
[5,6], banana [7,8], sisal [9,10], flax [11], coir [12,13], basalt [14],
oil palm wood flour [15] and sugar palm [16,17]. Numerous
researches had joined to endure further this development.
The tensile properties unidirectional of flax–glass fiber
reinforced phenolics composites is carried out by Yongli et al.
[11]. They have stated that rise of glass fiber’s content can
eventually enhancing the hybrid composites. Mariam et al.
[18] pursued this likely with hybrid glass/date palm wood flour
fiber reinforced recycled polypropylene composites to observe
its properties as well as its performance.
Misri et al. [16] on the other hand, had used the woven
glass/sugar palm fibers reinforced unsaturated polyester
hybrid composites to observe its mechanical properties by
considering different layer of fibers namely strand mat,
natural and hand woven of sugar palm fibers. They have
reported the hybridization to woven glass/sugar palm fibers
reinforced unsaturated polyester hybrid composites by compression molding increasing the mechanical properties. The
overall tensile and impact properties of woven glass/sugar
palm fibers reinforced unsaturated polyester hybrid composites were higher than the natural woven sugar palm fibers
used.
Moreover, it has already proved that hybridization of oil
palm empty fruit bunches (EFB) with synthetic fiber or natural
fiber will improve the mechanical properties of hybrid composite. Jawaid et al. [19] investigated that flexural and impact
strength of oil palm EFB with jute fibers reinforced epoxy
composites were fabricated by hand lay-up method. Result
indicated that the flexural properties of jute fiber and oil palm
EFB with the ratio (1:4) hybrid composite have good mechanical properties than those of pure EFB/epoxy composites. In
this study, it also observed that impact strength of pure EFB
composites is higher than hybrid composites is proved that
this composites is mainly dependent on the characteristics of
natural fibers.
Mohammed et al. [20] have developed the sugar palm
reinforced thermoplastic polyurethane composites and have
tested its fracture’s toughness. An excellent result has been
achieved in mechanical performance for sugar palm fiber
composites at 250 ␮m size. Moreover, previous studies done
by other research who are working with glass with sugar palm
with variation of polymer matrices such as thermoset unsaturated polyester [16], no other works shows that combination
between sugar palm and glass fiber reinforced thermoplastic polyurethane has been reported. In this work, sugar palm
and glass fibers were chosen to layer the hybrid composite by melt compounding shows remarkable effect from this
hybridization. Hence, a number of essentials testing methods from tensile, flexural and impact properties were studied
in this hybrid composite. The influence of hybrid ratio and
post tensile testing were investigated and the hybrid mechanisms were revealed with the aid of the scanning electronic
microscopy (SEM) observations.
2.
Experimental
2.1.
Materials
®
Estane 58311 TPU was supplied in pellet form with density of
1.13 g/cm3 by Pultrusion Sdn. Bhd. and was used as the polymer matrix. The sugar palm fiber (SPF) was collected from
sugar palm tree at Jempol, Negeri Sembilan, Malaysia. The
properties of sugar palm and glass fiber are shown in Table 1.
Please cite this article in press as: Afzaluddin A, et al. Physical and mechanical properties of sugar palm/glass fiber reinforced thermoplastic
polyurethane hybrid composites. J Mater Res Technol. 2018. https://doi.org/10.1016/j.jmrt.2018.04.024
ARTICLE IN PRESS
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Table 1 – Properties of sugar palm and glass fibers.
Properties
3
Density (g/cm )
Tensile strength (MPa)
Stiffness (GPa)
Elongation at break (%)
References
2.2.
Sugar palm fibers
Glass fibers
1.21
15.5
0.49
5.75
[21,22]
2.54
3450
72.4
4.8
[23]
Preparation of sugar palm
Firstly, sugar palm fiber was first washed with tap water for
several times to get rid of any impurities and unnecessary
things that attached to the SPF. The SPF was kept in an open air
for 24 h and dried in an air circulating oven at 60 ◦ C for 48 h.
The dry SPF grounded to get size of 10–15 mm using plastic
crusher machine then followed by using pulverize machine
then the particle SPF were sieved to obtain 125–250 ␮m.
SP/G were weighed in air using digital weighing scale and in
water using densimeter, MD-200S Mirage.
The thickness and weight of the composite specimens were
recorded for tests. 10 replicates of composite specimens with
the dimension of 20 mm × 20 mm × 3 mm were immersed in
distilled water with the room temperature 25 ◦ C. The data of
TS and WA were recorded after 72 h, 120 h and 168 h of water
immersion period.
3.2.
The SP/G composite hybrids were prepared using melt compounding technique followed by hot pressing molding process.
Sugar palm particles size 125–250 ␮m, chopped E-glass fiber
size 12.5 mm and thermoplastic polyurethanes in pellet form
were dried in an electric oven at 80 ◦ C for 48 h. Five sets of
SP/G/TPU composites (30/10, 20/20, 10/30 and 0/40) wt.% of
sugar palm particles reinforced thermoplastic polyurethane
were fabricated as seen in Table 2. The SP/G hybrid composites were prepared using blending, followed by hot pressing
molding process to achieve uniform distribution. Haake polydrive R600 was used in the mixing process at the optimum
processing parameters 190 ◦ C, 11 min and 40 rpm, temperature, time and rotating speed; respectively [21]. Vechno Vation
40 ton compression molding machine was used in the compression molding. The samples were pre-heated for 7 min at
190 ◦ C. Then they were full pressed for 10 min at 190 ◦ C. Finally,
they were cold-pressed for 5 min at 25 ◦ C.
3.
Characterizations
3.1.
Physical property of sugar palm reinforced TPU
hybrid composites
Density, thickness swelling (TS) and water absorption (WA)
of the composites were evaluated according to ASTM D4018,
ASTM D570, respectively. The developed hybrid composites of
Table 2 – Hybrid designation and composition of the
formulations.
Hybrid designation
Composition of hybrid formulations (wt.%)
30/10 SP/G
20/20 SP/G
10/30 SP/G
0/40 SP/G
TPU (60) + Sugar palm (30) + Glass fiber (10)
TPU (60) + Sugar palm (20) + Glass fiber (20)
TPU (60) + Sugar palm (10) + Glass fiber (30)
TPU (60) + Sugar palm (0) + Glass fiber (40)
Tensile test
The tensile test was performed on flat dog-bone shaped sample as per ASTM D618 [22] test standards using a universal
testing machine, LLYOLD Instruments. The specimen was
tested by a calibrated universal testing machine with a speed
of 50 mm/min. All the tests were performed for six samples
and average of six samples was taken as a final result.
3.3.
2.3.
Fabrication of hybrid SP/G reinforced TPU
composites
3
Flexural test
Flexural properties of developed SP-G/TPU hybrid composites were performed according to ASTM D790-03 [22] (3 point
bending) standard. The testing was executed using LLYOLD
(AMETEC) universal testing machine with 60 mm span length
and 12 mm/min crosshead speed.
3.4.
Impact test
Standard notched Izod impact test specimens were cut out
from the developed SPF/TPU hybrid composites plates using
abrasive water-jet machine (Excel WJ 4080) according to ASTM
D256 [22]. Averages of the five samples were taken to present
the final impact strength on SP-G/TPU hybrid composites.
3.5.
Scanning electron microscopy (SEM)
Morphological investigations were performed on the SPG/TPU hybrid composites with SEM machine Model (HITACHI
S-3400N). SEM instrument was used at an emission current
of 58 ␮A and acceleration voltage of 5.0 kV, and the working
distance was set to 6.2 mm. Before the SEM analysis, samples
were coated with gold.
4.
Results and discussion
4.1.
Density
The value of density measurements of sugar palm/glass fiber
reinforced thermoplastic polyurethane hybrid composites is
shown in Fig. 1, subjected to different fiber loading of (30/10,
20/20, 10/30 and 40/0) SP/G by weight fractions. The results for
density showed that with the addition of glass fiber to SP/TPU
composites, the density increased. In this case, the glass/TPU
(0/40 SP/G) composites exhibited the highest density as compared to other formulation of SP/G hybrid composites. Similar
work done on natural fiber/glass hybrid composites increases
with an increase in glass fiber loading to jute composites [23].
This result is mainly attributed to a higher density of glass
fiber to sugar palm fibers.
Please cite this article in press as: Afzaluddin A, et al. Physical and mechanical properties of sugar palm/glass fiber reinforced thermoplastic
polyurethane hybrid composites. J Mater Res Technol. 2018. https://doi.org/10.1016/j.jmrt.2018.04.024
ARTICLE IN PRESS
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apparent proposed that by substituting more glass fiber thus
will reduce the swelling properties, though it might be reduced
the content of sugar palm fiber in the hybrid formulation.
1.80
Density (g/cm3)
1.60
1.40
1.20
1.00
0.80
4.3.
0.60
Water absorption
0.40
0.20
0.00
30/10 SP/G
20/20 SP/G
10/30 SP/G
0/40 SP/G
Hybrid Designation
Fig. 1 – Density of SP/G reinforced TPU hybrid composites.
4.2.
Thickness swelling
Fig. 2 shows TS values obtained after 72, 120 and 168 h after
immersion tests. For the long term immersion, the 30/10 SP/G
hybrid composites had the highest TS value of 7.5% as compared to other composites. Though, 0/40 SP/G composites
exhibited the lowest TS value of 4.8% after 168 h respectively. It
was clearly shown that the lower TS value is belongs to higher
content of glass fiber reinforced TPU composites. In the case
of hybridization of SP/G, the 10/30 SP/G showing the lower
TS followed by 20/20 SP/G and 30/10 SP/G composites. It is
The values of WA of SP/G reinforced TPU hybrid composites as
depicted in Fig. 3 show that the higher content of sugar palm
fiber (30/10 SP/G) yielding the higher WA values. Among the
sugar palm/glass fiber hybrid composites, 10/30 SP/G composites had the lowest WA values of 5.03%, which demonstrates
8% reduction in WA compared to 20/10 SP/G composites. However the glass reinforced TPU composites (0/40 SP/G) exhibited
the lowest WA than other SP/G/TPU composites. The addition of glass fiber to the SP/TPU composites yields a positive
effect on reducing the water uptake of the specimens. It can
be assumed that the higher fiber loading of natural fibers,
the higher water uptake, while the higher fiber loading of
glass fiber resulting the lower moisture and water absorbed
by the hybrid composites. This finding was also in line from
previous work done by Kushwaha and Kumar [24] who figured out the water resistance properties increased when
addition of glass fiber by the epoxy and polyester/bamboo
composites.
Thickness Swelling (%)
9
72h
8
120h
168h
7
6
5
4
3
2
1
0
30/10 SP/G
20/10 SP/G
10/30 SP/G
0/40 SP/G
Hybrid Designation
Fig. 2 – Thickness swelling of SP/G reinforced TPU hybrid composites.
Water Absorption (%)
12
72h
10
120h
168h
8
6
4
2
0
30/10 SP/G
20/20 SP/G
10/30 SP/G
40/0 SP/G
Hybrid Designation
Fig. 3 – Water absorption of SP/G reinforced TPU hybrid composites.
Please cite this article in press as: Afzaluddin A, et al. Physical and mechanical properties of sugar palm/glass fiber reinforced thermoplastic
polyurethane hybrid composites. J Mater Res Technol. 2018. https://doi.org/10.1016/j.jmrt.2018.04.024
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25
900
700
600
15
500
400
10
300
Tensile Strength
5
Tensile Modulus
200
Tensile Modulus (MPa)
Tensile Strength (MPa)
800
20
100
0
0
30/10 SP/G
20/20 SP/G
10/30 SP/G
0/40 SP/G
Hybrid Designation
Fig. 4 – Tensile properties of SP/G reinforced TPU hybrid composites.
4.4.
Tensile properties
Different types of hybrid composites were prepared as sugar
palm/glass fiber reinforced thermoplastic polyurethanes. Different weight percentages of sugar palm/glass fiber were used
in hybrid composites. The total fiber content (sugar palm and
glass) of the composites was fixed at 40 wt.% while TPU matrix
at 60 wt.%. The tensile properties are displayed in Fig. 4. It
was shown that tensile strength of SP/G reinforced TPU hybrid
composites is enhanced by the addition of sugar palm. Nevertheless, by adding of 10 wt.% glass fiber to sugar palm TPU
composites increase the tensile modulus by about 20% as
compared to the single glass fiber (0/40 SP/G) reinforced TPU
composites. The attributes of hybrid composites are dependent on the properties of reinforcement. The tensile strength
of glass fiber is higher than sugar palm fiber as in Table 1 leads
to the extensibility of glass fiber than those of sugar palm
fiber. According to Phillips [25], at normal strain, the lower tensile strength of pineapple fibers fails first although they are
strongly adherence to and bounded to glass fiber reinforced
matrix. Eventhough, the both fiber are short and discontinuous, they remain to carry on the same load and contribute to
stiffness. The enhancement in tensile strength at lower fiber
loading of glass fiber (10/30 SP/G) can be correlated due to fact
that these fiber content of glass fiber can efficiently transfer load from the pineapple leaf fiber. AlMaadeed et al. [18]
demonstrated the mechanical properties of date palm wood
flour reinforced recycled polypropylene and analyzed that tensile strength was improved by substituting chopped E-glass
fiber. The findings of Akil et al. [26] investigated that tensile strength of the polyester/jute fiber composites increased
with increasing glass fiber content. Jayabal et al. [12] carried
out the study of mechanical properties woven coir/glass fiber
reinforced polyester composites improves by adding of glass
fibers.
The tensile modulus of hybrid sugar palm/glass fiber reinforced TPU composites, as shown in Fig. 4 proportionally
increased with glass fiber loading until 40 wt.%,. As can be
seen, the tensile modulus is affected by sugar palm and glass
fiber content. The tensile modulus of hybrid SP/G reinforced
TPU composites increased with increase of glass fiber content
at the different content of sugar palm fiber. When comparing tensile strength and modulus of SP/G reinforced TPU, the
tensile modulus is more increased by adding of glass fiber.
The reason why glass fiber in the hybrid SP/G/TPU composites
(Fig. 4) might be that the adhesion between sugar palm and
TPU is well attached to improve the modulus which is evaluated at low fiber content in the linear elastic region but tends
to break at higher fiber content approximate to ultimate tensile strength of the TPU matrix. The results show that the ratio
of sugar palm/glass fibers in the hybrid composites with the
addition of glass fiber content has a negligible effect on tensile
strength due to a limited interaction between TPU and glass
fibers. This finding agrees with Ghasemzadeh-Barvarz et al.
[27] who found that by adding only 10 vol.% of glass fiber leads
to 27% increase in tensile properties of flax–glass reinforced
polypropylene composites.
Fig. 5 gives the tensile stress–strain curves for 30/10, 20/20,
10/30, 0/40 wt.% SP/G during tensile test. The figure pointed out
that the higher content of sugar palm fiber at 30 wt.% and lowest content at 10 wt.% of glass fiber resulted in improvement in
the tensile stress and strain as compared with 20/20, 10/30 and
0/40 wt.%. This is evident from the micro-graph of a fractured
specimen in Fig. 9(a) which shows a large size sugar palm particle in the TPU matrix. The more sugar palm fiber cracking act
as barrier is presumed to have occurred during tensile fracture.
This process of improving tensile strength with higher sugar
palm content is true particularly at lower glass fiber loading.
The average tensile stress of five replicates specimens of 30/10
SP/G reinforced TPU composites was found to be 21.15 MPa
with tensile strain 18.31 mm/min. Tensile properties of 30/10
SP/G results in an improvement of 13% stress and 123% strain
as compared with to the tune of respectively as compared
the single glass fiber reinforced TPU (0/40 SP/G). It was found
that adding of sugar palm in glass fiber composites resulted in
an improvement in strain for 12.73 mm/min (20/20 SP/G) and
11.13 mm/min (10/30 SP/G) as compared to 8.21 mm/min (0/40
SP/G). It was noticed in this study that the by adding 30 wt.%
of sugar palm fiber the higher tensile strength, modulus and
the elongation break of the hybrid composite was observed.
Previous studies reported the same trend [28].
In hybrid composites, the tensile properties of the composites are mostly dependent on the percentage of elongation
at break and modulus of the single fibers [29]. The variation
of elongation at break with both sugar palm and glass fiber
loading are given in Fig. 6.
Please cite this article in press as: Afzaluddin A, et al. Physical and mechanical properties of sugar palm/glass fiber reinforced thermoplastic
polyurethane hybrid composites. J Mater Res Technol. 2018. https://doi.org/10.1016/j.jmrt.2018.04.024
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a
Tensile stress (N/mm^2)
25
20
15
10
5
0
-1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Tensile strain (%)
30/10 SP/G
b
Tensile stress (N/mm^2)
30
20
10
0
-10
-1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Tensile strain (%)
20/20 SP/G
c
Tensile stress (N/mm^2)
22
20
18
16
14
12
10
8
6
4
2
0
-1
0
1
2
3
4
5
6
7
8
9
10
T ensile st rain (%)
10/30 SP/G
Tensile stress (N/mm^2)
d
22
20
18
16
14
12
10
8
6
4
2
0
-1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
T ensile st rain (%)
0/40 SP/G
Fig. 5 – Typical tensile stress–strain of SP/G fiber reinforced TPU hybrid composites.
The result of elongation breaks displays an improvement
with higher content of sugar palm fiber in hybrid composites
while an inverse trend is noticed as the glass fiber content
increased in the composites. In substituting of sugar palm
fiber loading, the hybrid composites show a decreasing trend
in elongation at break of composites. The incorporation of
30 wt.% of sugar palm reveals the highest value of elongation at break of composites is 3.90 mm, while composites with
40 wt.% of glass fiber (0/40 SP/G) are discovered to have the
lowest value which is 1.00 mm of these properties. The reason is due to the fact that glass fiber has a low elongation fiber
compared to the sugar palm fiber [30]. Thus, incorporation the
sugar palm fiber with glass fiber has a high strain to failure
properties compared to the low extensibility of glass fiber as
seen in Fig. 6. In this case, glass fiber has low elongation will
fail first while the sugar palm fiber is able to withstand the
applied stress by load [29].
4.5.
Flexural properties
Fig. 7 shows the variation of fiber loading of (0/40, 10/30, 20/20
and 30/10) by wt.% SP/G for the flexural strength and modulus
of the composites. From the curve, it is evident that flexural
strength and flexural modulus of hybrid composites increased
with increase in glass fiber weight percentage. According to
Mishra et al. [31] in flexural testing, various mechanisms such
as compression, tension, and shearing happen promptly, by
adding of glass fiber content the shearing resistance of hybrid
Please cite this article in press as: Afzaluddin A, et al. Physical and mechanical properties of sugar palm/glass fiber reinforced thermoplastic
polyurethane hybrid composites. J Mater Res Technol. 2018. https://doi.org/10.1016/j.jmrt.2018.04.024
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4.50
Elongation at break (mm)
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
30/10 SP/G
20/20 SP/G
10/30 SP/G
0/40 SP/G
Hybrid Designation
Fig. 6 – Elongation of break of SP/G fiber reinforced TPU hybrid composites.
40
600
500
30
400
25
20
300
15
Flexural Strength
200
10
Flexural Modulus
5
0
Flexural Modulus (MPa)
Flexural Strength (MPa)
35
100
0
30/10 SP/G
20/20 SP/G
10/30 SP/G
0/40 SP/G
Hybrid Designation
Fig. 7 – Flexural properties of SP/G reinforced TPU hybrid composites.
composite will improve whereas reducing the shear failure.
The flexural strength of the GF reinforced TPU is found to be
31.09 MPa whereas the maximum flexural strength of hybrid
10/30 SP/G is found to be and 24.48 MPa followed by 20/20
SP/G (17.67 MPa) and 30/10 SP/G (17.24 MPa). This finding is
in agreement with Velmurugan and Manikandan [32] that
of which attributed the increase in the flexural strength of
Palmyra/glass composites to the great fiber-matrix adhesion
between Palmyra and glass fiber to the resin matrix.
The variation of flexural modulus of various SP/G fiber loading is shown in Fig. 7. The flexural modulus of the single glass
fiber reinforced TPU composites is found to be the optimum
at 509.70 MPa (0/40 SP/G), followed by 394.01 MPa (10/30 SP/G),
279.03 MPa (20/20 SP/G) and 266.69 MPa (30/10 SPG). Bachtiar
et al. [33] suggested similar results that flexural properties
jute-glass fiber reinforced epoxy resin composites showed an
increased flexural strength and modulus from 0 to 40 wt.% of
glass fiber loading as compared with the glass/epoxy composites.
In literature only a few examples of comparable hybrid
sugar palm/glass by using melt compounding can be tracked
down. For instance, sugar palm/glass hybrid reinforced
unsaturated polyester composites studied by Sapuan et al.
[17], manufactured by compression molding technique from
strand mat glass and sugar palm fiber, did show, in spite
of the slightly higher amount of glass fibers, a flexural
performance higher than sugar palm/unsaturated polyester
comparing flexural properties of kenaf/unsaturated polyester
and glass/unsaturated polyester produced by sheet molding
compound indicated a much lower difference being the region
of 18% flexural modulus as compared the glass/unsaturated
polyester composite [3].
4.6.
Impact properties
Impact resistance of composites is to determine the total
energy dissipated in the material before final failure occurs
[34]. The variation of the impact strength versus sugar
palm–glass fiber content in TPU composites is shown in Fig. 8.
Regarding the curve graph, the impact strength was
affected by sugar palm and glass fiber content. Incorporation
of glass fiber in the SP/TPU composites gives the variation in
impact strength of the hybrid composites. The higher impact
energy is with the single fiber content of TPU composites show
lower than 20/20 wt.% SP/G. As sugar palm increase from 10
to 30 wt.%, the impact strength starts to increase. Similarly,
Mridha et al. [15] found that the impact strength of oil palm
wood flour (OPWF) particles with less than 250 ␮ sizes have
been used as filler materials in the woven-glass-fiber reinforced epoxy composites increased with increasing oil palm
hybrid volume fraction.
Please cite this article in press as: Afzaluddin A, et al. Physical and mechanical properties of sugar palm/glass fiber reinforced thermoplastic
polyurethane hybrid composites. J Mater Res Technol. 2018. https://doi.org/10.1016/j.jmrt.2018.04.024
ARTICLE IN PRESS
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1
21
0.9
20.5
0.8
0.7
20
0.6
19.5
0.5
19
0.4
18.5
0.3
18
17.5
Impact Strength
0.2
Energy Absorption
0.1
Energy Absorption (J)
Impact Strength (kJ/m2)
21.5
0
17
30/10 SP/G
20/20 SP/G
10/30 SP/G
0/40 SP/G
Hybrid Designation
Fig. 8 – Impact properties of SP/G fiber reinforced TPU hybrid composites.
a
Fiber breakage
b
Fiber pull-out
Sugar palm
Glass fiber
d
c
Sugar palm
Glass fiber
Fiber pull out
Fiber breakage
Fig. 9 – SEM micrograph of cracks developed in the (a) 30/10 SP/G, (b) 20/20 SP/G, (c) 10/30 SP/G and (d) 0/40 SP/G (300×
magnification).
The evidence presented in impact properties as in Fig. 8
suggests that the higher impact strength in sugar palm fiber
containing over 10 wt.% may be that the fiber content is effective above this range to influence the impact property of the
hybrid natural-synthetic fiber composites. Furthermore, it is
to be noted that 30/10 SP/G have higher amount of sugar palm
fiber loading have larger particles in size which mostly appear
in the hybrid composites. The sugar palm particles assumed
to acts as barrier in the thermoplastic polyurethane and
that enhances the deformability especially at higher content.
Please cite this article in press as: Afzaluddin A, et al. Physical and mechanical properties of sugar palm/glass fiber reinforced thermoplastic
polyurethane hybrid composites. J Mater Res Technol. 2018. https://doi.org/10.1016/j.jmrt.2018.04.024
JMRTEC-448; No. of Pages 10
ARTICLE IN PRESS
j m a t e r r e s t e c h n o l . 2 0 1 8;x x x(x x):xxx–xxx
Uma Devi et al. [34] have found that hybridization of short
pineapple leaf fiber with glass fibers resulted in polyester
composites having higher impact resistance than the neat
glass/polyester composites. Moreover, Uawongsuwan et al.
[28] have found that hybridization of long jute fiber/glass
fiber-reinforced polypropylene composite with small amount
of 10 wt.% of glass fiber at the impact strength has increased
by more than 948%. The value is higher than jute fiber/PP composites. The increase in impact strength can be related to an
improved stress capability and thus to a limited contribution
of fiber-related mechanism such as fiber pull out.
4.7.
Scanning electron microscopy (SEM)
The scanning of electron microscopy of fractures surfaces of
the tensile specimen of 30/10, 20/20/, 10/30 and 40/0 wt.% of
SP/G reinforced TPU composites is shown in Fig. 9. High sample fiber loading of sugar palm is observed in Fig. 9(a) showing
a quite strong adhesion between the sugar palm and glass fiber
to TPU Matrix. This might be due to strong bonding between
TPU matrix and glass fibers are the reasons for enhanced in
tensile strength (Fig. 4).
The figure also indicates more fiber fracture and pull out
from the specimen and also the dislocation of fibers. Moreover,
the SEM morphology of the hybrid SP/G consists of two types
behavior are observed in Fig. 9(a), (b) and (c) is the surface
of hybrid composites due to tensile load. From Fig. 9(b) and
(c) more glass fiber stretching and another sugar palm fiber
breakage and pull out at the middle without any stretching.
Fig. 9(d) shows 40 wt.% of GF loading (0/40 SP/G) reinforced
TPU composites. For brittle nature of glass fiber is noticed from
the fractured mode in Fig. 9(d). An increase of tensile strength
(Fig. 4) of the hybrid composite with 10–30 wt.% of SP/G compared with the individual composite (0/40 SP/G) is due to the
good dispersion and increase in physical adhesion between
the SP/G fiber and the TPU matrix in the hybrid composite.
This similar observation was same with Gujjala, Ojha, Acharya
and Pal [35] who studied the woven jute-glass fiber reinforced
polyester using hand lay-up technique.
5.
Conclusions
The physical and mechanical properties of hybrid SP/G reinforced TPU composites have been investigated. It was found
that, the density, thickness swelling and water absorption
increased as the fiber loading of natural fiber increased. The
higher content of sugar palm in hybrid composite was 30/10
SP/G resulted the increased density, TS and WA values of
respectively. The substitution of glass fiber with 30 wt.% (10/30
SP/G) decreased the density, TS and WA. It was observed that
the incorporation of both sugar palm and glass fiber into
TPU matrix has resulted in an increase of tensile and impact
strength with increase in sugar palm fiber loading. The maximum tensile strength and modulus is observed for the hybrid
composite is 30/10 SP/G. The higher content of sugar palm
in hybrid SP/G reinforced TPU improved in tensile stress and
strain and has higher elongation at break as compared to 0/40
SP/G reinforced TPU composites. Nevertheless, incorporation
of 10 wt.% (10/30 SP/G) showed the maximum value of flexural
9
and strength after glass fiber composites (0/40 SP/G). The
hybrid composites (0/40 SP/G) have higher impact strength
than the composites based on glass fiber composites. Thus, it
is important to combine sugar palm and glass fiber to produce
hybrid thermoplastic composites of outstanding mechanical
performance.
Conflicts of interest
The author declares no conflicts of interest.
Acknowledgements
The authors extend their gratitude to the Ministry of Higher
Education for providing HICOE Grant No: 6369108 to INTROP,
Universiti Putra Malaysia (UPM) for supporting this research
work. The authors also grateful for the financial support
from Universiti Putra Malaysia through Putra grant no. GPIPS/2015/9441501. Author would also like to thank the Ministry
of Higher Education for the MyBrain15 scholarship to ist
author.
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Please cite this article in press as: Afzaluddin A, et al. Physical and mechanical properties of sugar palm/glass fiber reinforced thermoplastic
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