Influence of high molecular weight poly(ethylene adipate) on the crystallization behavior and mechanical properties of biodegradable poly(l-lactide) in their immiscible polymer blend

A fully biodegradable polymer blend consisting of poly(l-lactide) (PLLA) and poly(ethylene adipate) (PEA) with relatively high number average molecular weight of 8000 g/mol (80/20 in weight ratio) was prepared through a solution and casting method. The dynamic mechanical analysis and scanning electron microscopy studies confirmed that PLLA was immiscible with PEA. The crystallization behavior, crystal structure and mechanical properties of PLLA/PEA blend were investigated and compared with those of neat PLLA. In the immiscible blend, the blending with PEA enhanced the nonisothermal cold and melt crystallization behavior, decreased the isothermal melt crystallization rate and retained the crystallization mechanism and crystal structure of PLLA. The tensile test results revealed that the ductility and toughness of PLLA phase were significantly improved by the blending with high molecular weight PEA.