Study On Full Biodegradable Composites: Ramie Fibre Reinforced PLLA-PCL Composite Prepared By In Situ Polymerization Process

With a greater concern for environmental protection, natural fibers such as Ramie fiber, Flax fiber, Jute fiber, bamboo fiber and wood fibers as reinforcement in plastics have increased dramatically during the last few years. But most the matrix of the natural fibers reinforced composites were not biodegradable resin, the composites also took destruction to the environment.In this study PLLA oligomer and NCO-terminated poly(ε-caprolactone) prepolymer were selected as matrix. Thermoplastic full biodegradable composites based on Ramie fiber and PLLA-PCL matrix was prepared by in situ polymerization. Surface treatment of Ramie fiber with KH550 and KH560, in situ polymerizing PLLA-PCL, composite process, length of Ramie fiber , content of Ramie fiber were systematically studied. The results showed that:1 , The best time and concentration of KH550 or KH560 were set at 30min and 1%. After treating with KH550 or KH560 , the hydrophile of Ramie fiber was reduced obviously, but the mechanical properties oframie fiber reduced a lit.2N The temperature and time of in situ polymerizing Ramie fiber reinforced PLLA-PCL composite were at 80 °C and 4h. During the in situ polymerizing process, the - NCO groups could react with - NH2 groups of KH550, so there would be resin grafting to Ramie fiber. And the epoxy groups of KH560 did not react with - OH of PLLA.3> Both KH550 and KH560 could improve the interface between Ramie fiber and PLLA-PCL, but KH550 was much better than KH560. 4> Both Ramie fiber and PLLA-PCL could not resist high temperature, so the mechanical properties of Ramie reinforced PLLA-PCL composite were influenced by the temperature and time of compression moulding. Under 155 °C, warm-up 5muK pressing 3min, the mechanical properties of Ramie fiber reinforced PLLA-PCL composite got the best.5^ When Ramie fiber were 5-6mm length and with 45% content, the mechanical properties of Ramie fiber reinforced PLLA-PCL composite got the best, and the tensile strength > Impact strength and Flexural strength were 36.21NQ^ 131.9 J/m and 64.2MPa respectively.