Effect of kenaf fibre loading and thymol concentration on the mechanical and thermal properties of PLA/kenaf/thymol composites

• Poly(lactic acid) composites containing kenaf fibre and thymol were prepared.
• Kenaf fibre reinforces the polymer and improves mechanical strength.
• Composites with thymol showed improved processability.
• The composites show potential for food packaging applications.

Composites of poly(lactic acid) (PLA) containing up to 40% (w/w) of kenaf fibre and up to 10% (w/w) of thymol were studied to evaluate the mechanical and thermal properties. These composites were compared with control systems containing either no fibre or no thymol and were prepared using melt blending and compression moulding techniques. The composites with 10% (w/w) thymol had the lowest tensile strength with slightly higher flexibility compared with those systems containing lower concentrations of this additive. The tensile properties of composites containing 5% (w/w) thymol demonstrated that the addition of fibre to the PLA/kenaf composites was affected more than the incorporation of the thymol alone. Thermogravimetric analysis of neat PLA and PLA/kenaf composites incorporated with 5% and 10% (w/w) thymol revealed no significant changes in the decomposition temperature. Analysis by differential scanning calorimetry, however, showed a decrease in all of the key thermal transitions with the addition of 5% and 10% (w/w) thymol into the neat PLA and PLA/kenaf composites. The results of the mechanical and thermal properties tests suggest that thymol acts as a plasticizing agent in this composite.