Kenaf Derived Cellulose (KDC)/Poly(lactic acid) (PLA) Composites: Optimisation of Melt Mixer Parameters via Response Surface Methodology

Abstract

Kenaf-derived cellulose (KDC) reinforced poly(lactic acid) (PLA) composites with constant filler loading of 5% KDC were prepared by melt compounding and compression moulding. Kenaf bast fibre was chemically treated by chlorination and mercerisation to obtain the α-cellulose and evaluated as the KDC. Mixer variables, namely mixing temperature (160 to 180°C) and mixing time (10 to 30 min), were screened and optimised with the response surface method (RSM) to maximise the tensile strength, minimise the stock temperature (below 200°C to avoid fibre degradation) and monitoring the mixing torque curves (to ensure composite is well mix at sufficient duration). The variables were selected as two independent variables, whereas the tensile strength and stock temperature were selected as the response variables in this response surface study. The mixing temperature term was significant, with a P value less than 0.0500 for both tensile strength and stock temperature. The optimum variables were determined at 170⁰C and 30 min based on the overlaid contour of tensile strength, stock temperature, and stabilisation zone via mixing torque of composites at various loading.