Polylactic Acid /High-Ratio Natural Kenaf Fiber Biocomposite Sheets Processed by Calendering Melt Mixing Technique

Biodegradable polymers reinforced with cellulose-based natural fibers are of high strategic necessities toward the environment preservation acts. Numerous studies have reported the formulation of polylactic acid based bio-degradable micro-composites loaded with natural fibers. However, the use of high natural filler content has been shown to be an underlying challenge in terms of bio-based composites’ processability. This study mainly aims at the processability of thermoplastic bio-degradable composites of polylactic acid/Kenaf using a two-roller calendering machine on the melt mixing manner assisted with high shear forces. The results indicated successful processing of the green composites containing 0-30 wt% of kenaf using the sheet forming process from direct mixing of kenaf and polylactic acid granules. It was shown that the tensile modulus increased by 130% and the density of the parts decreased by ~10% at the filler loading of 30 wt% with respect to the neat polylactic acid whilst the tensile strength decreased irrespective of the filler loading. The results further showed the melting temperature decreases supporting better processability by increasing the kenaf fraction. The crystallization against the decrease in the density was correlated to the decrease in the toughness of the parts. Moreover, the morphology and structural studies whilst supporting the changes in mechanical performance supported the effect of processing on the fillers orientation and the possible presence of agglomerated phase at higher filler loadings.