Novel Strategy to Improve the Performance of Poly(l-lactide): The Synergistic Effect of Disentanglement and Strong Shear Field

Abstract

As a biobased and biodegradable material that can replace traditional petrochemical-based polymers, poly(L-lactide) (PLLA) shows great application potential. However, its widespread application still faces some obstacles, mainly associated with the poor thermal resistance, because the molecular chains of PLLA are semirigid and of poor regularity. Therefore, the crystallization rate is low, making it difficult to crystallize during the molding process, and the finally obtained PLLA is almost amorphous. In this work, the entanglement density of molecular chains was reduced to promote the molecular chain mobility. Then, PLLA was processed in combination with a strong shear field provided by the vibration injection molding technology. The results show that the synergistic effect of disentanglement and strong shear field can significantly accelerate the crystallization kinetics of PLLA. In addition, due to the better mobility, molecular chains of PLLA tend to be more regularly arranged along the flow direction under strong shear field, resulting in thicker shear layers as well as the generation of denser and more perfect shish-kebab structures. As a result, PLLA material with enhanced performance is obtained, which favors to broaden the application range of PLLA.