Application of β-sheet proteins as a compatibilizer in injection molding of kenaf core/polypropylene composites

ABSTRACTInjection-molding was performed using ethylene–propylene copolymer as the matrix by varying the physicochemical treatment of the reinforcement, i.e., core portion of kenaf stem that was dry-distilled and coated with or without β-sheet protein derivatives. Although dry distillation reduced the moisture content, the Charpy impact strength of the molded composites was low. When molding was performed using the fillers coated with β-sheet protein derivatives, especially coated with liquid silk (LS), a satisfactory Charpy impact strength of the molded composites was markedly gained. Thus, the β-sheet protein derivatives had potential to work as a compatibilizer. Coating the fillers with β-sheet proteins was also effective in suppressing the generation of silver streaks on the surface of composites and in preventing the occurrence of defective injection molding.