Toward Highly Toughened Polylactide/Polycaprolactone-Based Polyurethane Blends With Shape Memory Property via Reactive Blending

Reactive blending has proven to be a versatile and efficient method for enhancing the impact toughness of polylactide (PLA). PLA/cross-linked polycaprolactone-based polyurethane (c-PCLU) blends are prepared by reactive blending of PLA with PCL triol and hexamethylene diisocyanate (HDI). The reaction mechanism, compatibility, crystallization behavior, rheology behavior, mechanical performance, and shape memory property are thoroughly studied. The FTIR results confirmed that the N=C=O groups of HDI reacted with the hydroxyl groups of PLA and PCL triol, leading to the in situ formation of c-PCLU and PLA-co-PCLU. The phase morphology exhibits a sea-island structure, suggesting incompatibility between the two phases. The compatibility of the blends is improved with the increase of the PCL triol feeding ratio. The crystallization ability of PLA is retarded in the reactive blend. Both the elongation at break and the shape recovery ratio increase with c-PCLU content, reaching up to 94.0% and 92.6%, respectively. These findings show that the formation of c-PCLU greatly enhanced the toughness and shape memory performance of PLA.