Effect of steam explosion and silanization of hemp fibers on polylactic acid biocomposites; analysis of mechanical-thermal properties and fungal biodegradation

Alkaline pretreated hemp fibers were modified by steam explosion and/or silanization before being compounded with polylactic acid (PLA). The fungal biodegradation of the PLA/hemp fibers composite was investigated using Aspergillus niger TISTR 3153 in an aqueous medium for 28 days, following the ISO 846: 1997 standard method. The influence of the different physicochemical modifications of hemp fibers on the fungal biodegradation of the composite was evaluated in terms of molecular weight, chemical structure, mechanical properties, thermal properties, and hygroscopic properties. The results showed that the modulus of all composites were averagely increased by 109%, compared to neat PLA. All the PLA/hemp fiber composites better retained their properties after fungal biodegradation than neat PLA. Therefore, the physicochemical treatments of fibers after alkaline pretreatment promoted the resistance of the composite to fungal biodegradation. The treatment of hemp fibers in the present work was alkalization followed by silanization, which resulted in a PLA-based composite that was suitable for outdoor applications.