Understanding the Reinforcing Mechanisms in Kenaf Fiber/PLA and Kenaf Fiber/PP Composites: A Comparative Study

Abstract

This study focused on exploring the feasibility of green composites made from biodegradable and renewable materials as potential alternatives to petroleum polymer composites and understanding the reinforcing mechanisms in composites containing kenaf fibers (KF). KF-reinforced poly(lactide) acid (PLA) composites were made using melt compounding and injection molding, and their properties were compared to that of KF-reinforced polypropylene (PP) composites. The flexural properties and thermomechanical behavior were determined as a function of the fiber content, the crystallization of PLA and PP was studied using X-ray diffraction and differential scanning calorimetry, and the composites’ morphology was investigated using scanning electron microscopy. It was concluded that PLA exhibits higher modulus and Tg compared to those of neat PP. The modulus of the composites at 40 wt% fibers is 6.64 GPa and 2.96 GPa for PLA and PP, respectively. In general, addition of kenaf results in larger property enhancement in PP due to better wetting of the fibers by the low melt viscosity PP and the crystallization behavior of PP that is significantly altered by the fibers. The novelty of this work is that it provides one-to-one comparison of PLA and PP composites, and it explores the feasibility of fabricating green composites with enhanced properties using a simple scalable process.

Mechanical and degradation properties of natural fiber‐reinforced PLA composites: Jute, sisal, and elephant grass

“…The reduction in the strength may also be due to bad dispersion of fiber in the matrix . It was stated that as the fiber content increases there is more fiber surface that needs to be wetted by the polymer in order to have good contact and sufficient stress transfer . But due to less polymer that is available at higher fiber loading to wet the fibers, so the strength should either reach a plateau value or start decreasing upon further addition of fibers.…”

“…It is stated that the treatments have a lasting effect on natural fibers such as the removal of amorphous components of fibers, especially on fiber stiffness . The increase in the strength may be due to interfacial adhesion of fiber and matrix and also due to better mechanical interlocking between matrix and fiber after treatment . Also bleaching with H 2 O 2 resulted in smooth, compact and clean fiber surfaces which increased the surface area of contact between fiber and the matrix.…”

Preparation and properties of successive alkali treated completely biodegradable short jute fiber reinforced PLA composites

“…The reduction in the strength may also be due to bad dispersion of fiber in the matrix [1]. Han et al [24] stated that, as the fiber content increases there is more fiber surface that needs to be wetted by the polymer in order to have good contact and sufficient stress transfer, and due to less polymer that is available at higher fiber loading to wet the fibers, hence the strength should either reach a plateau value or start decreasing upon further addition of fibers.…”

Mechanical, dynamic, and thermomechanical properties of coir/pineapple leaf fiber reinforced polylactic acid hybrid biocomposites

“…PLA is one of the most extensively studied biopolymers mainly due to its high mechanical and thermal properties , which are comparable to those of polystyrene , and to its easy production from lactic acid monomer, which is derived from corn starch. PLA exhibits higher storage modulus and flexural properties, compared to polypropylene (PP) , and is naturally decomposable to minimize environmental loads . Natural fiber‐reinforced PLA composites have been reported extensively, though providing much variability in mechanical properties .…”