Manipulating the Strength-Toughness Balance of Poly(L-lactide) (PLLA) via Introducing Ductile Poly(epsilon-caprolactone) (PCL) and Strong Shear Flow

摘要

Poly(L-lactide) (PLLA) is a renewable and completely biodegradable material. However, due to its semirigid molecular chain, asymmetric carbon atoms, and poor regularity of the molecular chain, PLLA has poor crystallization ability and is almost amorphous under the traditional processing conditions, resulting in poor toughness and thermal resistance that severely limit its widespread use. In this work, biodegradable poly(epsilon-caprolactone) (PCL), a rubbery polymer, was added into PLLA to promote the mobility of PLLA molecular chains and then exerted the strong shear flow field generated by multiflow vibration injection molding (MFVIM) technology. The results demonstrate that the coexistence of ductile PCL and strong shear field could improve the crystallization ability and thermal resistance of PLLA significantly. The crystallinity increases to 40.7% and the Vicat softening temperature is up to 138.4 degrees C. Finally, a strength-toughness-balanced PLLA material is obtained, which can widen the application range of PLLA.