Efficiently enhancing toughness of polylactic acid film through synergistic effect of bamboo charcoal and carbon fiber.

Polylactic acid (PLA) film has great potential for application, but its poor toughness is an insurmountable gap at present. For this issue, two kinds of carbon materials (bamboo charcoal and carbon fiber) with different shapes are used as toughening agents, and KH-550 silane coupling agent is introduced to form a solid link between the toughening agents and the PLA matrix to improve the compatibility. When PLA is stretched and under high elastic deformation, an ultra-fine cavity is formed on one side of K-UFBC (KH-550 modified ultra fine bamboo charcoal), which absorbs most of the fracture energy and performs effective stress transfer. The longitudinal rod-like structure of K-CF (KH-550 modified carbon fiber) acts as a "reinforcing bar", disperses part of the longitudinal tension and reduce the overstretching of the holes near K-UFBC. The two mechanisms work together to achieve toughening effect. The crystallinity of prepared composite film is 2.4 times higher than that of the pure PLA film, and its toughness (fracture tensile rate) increase by 340.73 %. In this study, a new toughening strategy for PLA was proposed to provide a theoretical basis for constructing high-toughness PLA materials and expanding their further application.