Page 40 - New Cloth Market December 2022 Digital Edition

Industrial Hemp Fibers: An Overview

ance of thermomechanical degrada- thermoplastic composites can also be Song et al. [69] investigated the me-
tion, and a larger amount of natural fi- recycled by chemical or energy meth- chanical properties of hemp fiber-rein-
bers that can be added to the com- ods as described above. In addition, forced PLA composites, with a focus
posite matrix. However, the effcient thermoplastic composites can also be on the viscoelastic and thermal behav-
recycling of thermosets is still a chal- recycled by grinding followed by repro- ior. Twill and plain-woven hemp fabrics
lenge and thermoplastics have also the cessing by a number of techniques were used as reinforcements. The twill
advantage of providing a greater flexi- such as injection molding [64]. fabric was found to be suitable for re-
bility in the design [11,30]. inforcing a PLA resin with higher im-
Hemp fibers are renewable and can be pact strength and better thermal and
Resin transfer molding, sheet molding incinerated at the end of the material viscoelastic behavior than the plain
compound, pultrusion, vacuum-assist- lifetime. From an eco-performance woven one, due to fewer intersections
ed resin transfer molding, and hand point of view, mechanical recycling is and closer packing of the twill fabrics.
layup are the most common process- favored over thermal recycling in the
ing methods for thermoset composites. case of natural fiber-reinforced com- Synthetic and Hemp
Vacuum-assisted methods are used to posites. Problems associated with ther- Fiber-Reinforced Composites
produce thermoset composites for mal degradation during recycling and Synthetic and hemp fiber-reinforced
high-end applications. The advantag- reprocessing may significantly lower composites have been used to en-
es of vacuum-assisted methods are the eco-performance of natural fiber hance the performance and properties
the following: (1) high fiber content lam- composites. Life-cycle assessment of the resultant composite materials as
inates, (2) lower void contents, and (3) studies show that the advantage of well as reduce moisture absorption and
improved fiber wet-out due to pressure natural fibers over glass fibers are balance the fiber’s cost [70]. As sug-
[11,61]. Sèbe et al. [62] manufactured mainly related to their low weight rath- gested by Sature and Mache [31], the
hemp fiber-reinforced polyester com- er than recyclability [65]. reinforcement of natural fibers with
posites using resin transfer molding glass fibers may work as a skin pro-
(RTM). They obtained good quality Hemp Fiber-Reinforced tection.
parts with high flexural properties. How- Hybrid Composites
ever, the impact strength of these Samanta et al. [71] performed a com-
Hybridization in polymeric materials
materials was found to be fairly low to parative study on hemp/glass fiber and
can be extended to a blend of one or
compete with glass fiber in structural bamboo/glass fiber hybrid reinforced
more polymers reinforced with one or
applications. epoxy composites. It was found that
more types of fibers. Hybridization pro-
hemp/glass fiber hybrid composites
Recycling of Thermoplastic and vides new opportunities to broaden the have a higher strength under compres-
Thermoset Polymeric Matrices applicability and improve the proper- sive load than bamboo/glass fiber hy-
ties of composite materials, especial- brid composites, whereas under ten-
Recyclability is becoming increasing- ly in high-end applications [3,7]. sile load the opposite scenario was
ly important. A major advantage of ther- Hence, hybrid composites can provide observed.
moplastics over thermosets is the abil- a high stiffness and strength, improve
ity to reuse the material. Thermoplas- the impact and fatigue resistance, pro- The effects of water absorption on the
tics can be heated above their melt tem- vide high fracture toughness, and si- mechanical properties of hemp and
perature and reformed into a new multaneously cut the weight and/or hemp/glass fiber hybrid reinforced
shape. The thermoset composites can total cost [66,67]. polypropylene composites were inves-
be recycled by three methods: (1) tigated by Panthapulakkal and Sain
chemical recycling refers to process- In addition, textile engineering has pro- [26].
es like pyrolysis in which the material vided affordable solutions for produc-
Hemp fiber-reinforced PP composites
is heated in an oxygen-free environ- ing hybrid fabrics, with controlled fiber
showed a significant reduction in
ment to produce one or more recover- content, fiber orientation, and roving
strength and stiffness due to the ab-
able substances, (2) in particle recy- texture. The most commonly hybrid
sorbed moisture, which resulted in the
cling, the thermoset composite is me- fabrics used as reinforcement are plain
debonding of the matrix–fiber interface.
chanically milled into particles to be (warp fibers alternately weave over and
The hybrid composites had a signifi-
used as a filler in new plastic or com- under the weft fiber in a regular pat-
cantly decreased water absorption by
posite applications as a replacement tern), twill (one or more warp fibers al-
40%, although the incorporation of
for calcium carbonate or talc, and (3) ternately wave under or over the weft
glass fiber did not have any significant
energy recycling refers to the possibil- fibers and are repeated in a regular
effect on the strength properties of the
ity of incinerating the material to re- manner), and satin (twill weave modi-
aged composites.
cover energy from its organic portion fied with fewer intersections of weft
[63]. Similar to thermoset composites, and warp) [4,68]. Akil et al. [16] studied the effect of
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