Flexibility Improvement of Poly(L -lactide) by Reactive Blending With Poly(ether urethane) Containing Poly(ethylene glycol) Blocks

Abstract

Poly(L-lactide) (PLLA) is melt blended with poly(ether urethane) (PEU) based on poly(ethylene glycol) blocks via a chain-extension reaction by diisocyanate as a chain extender to improve its flexibility without sacrificing comprehensive performance. The elongation at break of the blends with triphenyl phosphate (TPP) as a reactive blending additive is much higher than that without TPP by physical blending. When 10 wt% PEU is blended, the former elongation reaches to 298%, while the latter one is only approximately 20%. The reactive blending forms a PLLA–PEU block copolymer, thus improving their compatibility. When the weight-average molecular weight (Mw) of PEUs is 18–90 kg mol−1, the effect of Mw is very little on tensile properties of blends. The rheological properties of the blends are modified through the content and molecular weight of PEU. The complex viscosity (η*) of PLLA/PEU blends increases with increasing Mw of PEU. The η* of the PLLA blend containing 5 wt% PEU in Mw 73 kg mol−1 is higher than that of neat PLLA. The water absorption of the PLLA/PEU blends enhances because of the hydrophilicity of PEUs versus neat PLLA.