HARDENING OF SILK SERICIN-g-PLA/MARL BIOCOMPOSITES BY POLYBENZOXAZINE

摘要

This work emphasizes the synthesis of a graft copolymer, Sericin-g-PLA, having marl as a filler. The graft copolymer from biodegradable PLA was developed to reduce PLA brittleness and cost. Polybenzoxazine was used to modify the strength of the biocomposite product. In this work, polybenzoxazine precursor was synthesized from aliphatic diamine, bisphenol-A, and paraformaldehyde by using a faster quasi-solventless approach with 88% yield. The synthesized polybenzoxazine was blended with marl to improve its mechanical properties. Due to the poor interfacial adhesion between the marl and the polymer matrix, revealed by SEM, (3-aminopropyl) trimethoxysilane and stearic acid were chosen as surface modifying agents of marl. The effect of the surface treatment on the mechanical properties and morphology of polybenzoxazine-marl composites were studied. Afterwards, the graft copolymer, filled with modified surface marl, was blended with the polybenzoxazine precursor. The chemical structures of the graft copolymer and precursor were confirmed by FTIR and ~1H NMR. The DSC and TGA technique were used to study the thermal properties. The mechanical properties of the biocomposite hardened by polybenzoxazine were improved significantly.