Hybrid micro-composite sheets of Polylactic Acid (PLA)/Carbon Black (CB)/natural kenaf fiber processed by calendering method

Bio-composites filled with natural and bio-fibers can lead to novel green products. However, in terms of processing, there still exist serious challenges in the development of bi-based parts with respect to the materials selection and limitations associated with the fabrication route. Further issues rise when a uniform and homogenous blending of bio-based constituents is required. This study examines the feasibility of two roller mixer method (calendering) in the sheet fabrication of natural kenaf fiber/carbon black (CB) reinforced polylactic acid (PLA) on the basis of melt mixing. To do this, composites of 20 wt% kenaf, based on an optimized filler content, were reinforced with 0–10 wt% of CB to enhance the processability and to evaluate the synergistic effect of CB on kenaf/PLA parts. The results showed a 75% increase in the modulus of the pure PLA filled with 20 wt% kenaf whilst representing the greatest tensile strength amongst kenaf/PLA specimens. Specimens reinforced with 5 and 10 wt% of CB exhibited enhancement in the elongation at break with respect to the reference neat kenaf/PLA composites, which was attributed to the lowered crystallites size and softer interfacial interphase. However, with the addition of only 5 wt% of CB, the tensile modulus and the crystallization improved by ~ 50% compared to that represented by neat kenaf/PLA parts. The microstructural images confirmed the aligned kenaf phase, dispersion state and interfacial bonding of the CB/kenaf/PLA specimens in correlation with the thermal and mechanical response of the specimens.