SAMPE Journal - March/April 2023 - 23

INTRODUCTION
Increase in awareness of sustainability, strict
environmental legislation regarding the use of
biodegradable and recyclable materials has led
to the increase in demand and use of natural
fiber composites1
. Additionally, due to the several
advantages of natural fiber compared to synthetic
fibers, the global natural fiber composites market
is projected to grow from $4.46 billion in 2016
to $10.89 billion by 20242
. Some advantages
are low cost, abundant availability, low density,
high specific strength and
modulus,
natural fibers, bamboo fibers (BF) are one of the
commonly used natural fibers with
(low
)
energy consumption) low carbon dioxide (CO2
emissions and biodegradability3,4. Among several
worldwide
annual production of 30,000,000 tons3,5. These
fibers are generally used for reinforcing polymer
matrix due to their low density (0.6-1.1 g/cm3
),
low cost ($0.3-0.5/kg), high strength (140-800
MPa) and modulus (11-32 GPa)6
. BF reinforced
composites are being used in several sectors such
as automotive, construction and sports equipment
however are limited to non-structural and semistructural
parts. This is due to the wide variation
in fiber quality, lower mechanical properties as
compared to synthetic fibers, hydrophilicity, poor
compatibility with hydrophobic polymers, lower
thermal stability and processing temperature2
.
One approach to improve the properties of the BF
reinforced composites or any other composites is
hybridization which includes a combination of two
or more materials and/or processes.
There is emerging research interest in
hybrid
composites because of the freedom of choice and
distribution of reinforcement, matrix constituents
and availability of different manufacturing
processes1,7,8
. The idea of hybrid composite
is to combine the advantages and reduce the
shortcomings of individual component(s). As
example, natural fibers are economical, easily
accessible and sustainable while carbon fibers
(CFs) are expensive but offer high strength and
high modulus3
. Kore et al.1
observed increase in
flexural strength, flexural modulus and impact
strength of 30wt% BF reinforced polypropylene
(PP) by 40%, 75% and 192% respectively by adding
32wt% of CF. Dhakal et al.8
found enhancement in
the tensile strength and modulus of the flax/epoxy
composites by 650% and 400% on hybridizing with
50wt% CF. Alwekar et al.9
continuous glass fiber reinforced thermoplastic
(CFRTP) tape overmolded long fiber reinforced
thermoplastic (LFT) composites fabricated
extrusion compression molding technique (ECM),
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studied the properties of
where authors found an increase in flexural
strength and modulus of overmolded composites
by 119-142% and 77-65% respectively, compared to
LFT composites.
Commercially available Polyacrylonitrile
or PAN based CF offers excellent mechanical
properties (strength - 5000MPa and modulus- 350
GPa)10
however these are uneconomical ($30/lb)
for automotive markets11,12. Oak Ridge National
Laboratory (ORNL) developed textile grade CF
(TCF) using textile grade PAN precursor which
exhibits good mechanical properties (modulus- 275
GPa) and has estimated cost between $5-10/lb11
. In
this study, TCF- PP tape produced in an in-built lab
scale hot melt impregnation line was overmolded
with the BF- PP obtained from a low shear single
screw extruder. The primary objective of this study
was to investigate the effect of overmolded TCF
tape on BF-PP composites fabricated using the
extrusion-compression molding (ECM) technique
on their mechanical properties and density. Flexural
and interlaminar properties of the composites
were evaluated per ASTM D790 and ASTM D2344
standard testing methods whereas scanning
electron microscopy (SEM) was conducted to study
MARCH APRIL 2023
|
SAMPE JOURNAL |
23
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SAMPE Journal - March/April 2023

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