Facile Fabrication of Lightweight Shape Memory Thermoplastic Polyurethane/Polylactide Foams by Supercritical Carbon Dioxide Foaming

Abstract

Lightweight shape memory thermoplastic polyurethane (TPU)/polylactide (PLA) foams with favorable mechanical properties and anti-shrinkage properties were prepared by a facile and green supercritical carbon dioxide foaming technology in this work. The introduction of cells enhanced the shape recovery ratio of TPU/PLA blends from 72.7 to 91.7% due to the good resilience and deformability of cells. Meanwhile, the existence of PLA and crystals in TPU/PLA foams improved the shape fixing ratio of TPU/PLA foams to 92.7% by restricting the movement of TPU molecular chains. The shape memory properties of TPU/PLA foams can be tuned by the control of the cell structure and expansion ratio. Additionally, the addition of PLA restrained the shrinkage of TPU/PLA foams, and the expansion ratio of TPU/PLA foams increased to 7.1. The mechanical properties of TPU/PLA foams were enhanced by the addition of PLA.