Shape recovery behavior of polylactic acid/thermoplastic polyurethane polymer blends

Abstract

Polylactic acid (PLA) and thermoplastic polyurethane (TPU)-based blends were prepared by twin-screw extruder and conventional injection molding (CIM) machine at various weight ratios of PLA/TPU, that is, 90/10, 80/20, and 70/30. The prepared blends were investigated for their shape memory properties by performing shape deformation and recovery experiments at various temperatures and bending angles. During the deformation process, TPU acted as a toughening agent that prevented the PLA/TPU blends from distortion. Hence, the temporary shape can be kept as the internal stress was stored in the blends. On heating above the glass transition (Tg) temperature of PLA, the deformed parts recovered their original shapes quickly along with the release of the stress. The prepared blends were found to exhibit significant shape memory properties at the TPU content of 10 wt%. The recovery rate was found to reach up to approximately 95%. Such shape memory polymers found fascinating applications in aerospace engineering, engineering plastics, biomedical implant materials, and textiles.