Preparation And Properties Of Polylactic Acid-Based Shape Memory Blends Using Melt Mixing

Polylactic acid(PLA) based shape memory material can spontaneously recover its original shape, but also has good biocompatibility and biodegradability, so its potential applications are very broad. In this paper, PLA/ethylene-octene copolymer grafted glycidyl methacrylate(POE-g-GMA) shape memory blends, PLA/poly propylene carbonate(PPC) shape memory blends, and PLA/thermoplastic polyurethane(TPU)/polyethylene glycol(PEG) shape memory blends are prepared by melt mixing, and PLA-based three-way shape memory material are prepared by layer composite technology. The microstructure, rheological properties, thermal properties, mechanical properties and shape memory properties of prepared samples are studied, and the mechanism of their shape memory are further discussed.POE-g-GMA reacts with PLA, which improves their compatibilization. POE-g-GMA reduces glass transition temperature and cold crystallization temperature of PLA, and greatly improves its toughness. The impact strength of PLA/POE-g-GMA(40 wt%) blends is up to 49.3 kJ/m2, which is about 60 times of that of PLA. PLA/POE-g-GMA blends exhibit good shape memory properties, and their shape fixing rate and shape recovery rate decrease with increasing POE-g-GMA content. When POE-g-GMA content is 10 wt%, the blend exhibits the highest shape memory property. PPC and PLA are partially compatible. PPC can increase the toughness of PLA. The storage modulus and complex viscosity of PLA/PPC blends increase with increasing PPC content, and this trend is more obvious at low frequencies. PLA/PPC blends exhibit good shape memory properties, and their shape fixing rate and shape recovery rate decrease with increasing PPC content. When PPC content is 30 wt%, the blend exhibits the highest shape memory property. Although the compatibility between PLA and TPU is not good, the addation of TPU can improve the toughness of PLA. A small amount of PEG can improve the compatibility between PLA and TPU, so it can still improve the toughness of PLA. However, an excess of PEG cannot improve the compatibility between PLA and TPU, and cause a substantial decline in the toughness of PLA. PEG reduces the storage modulus and the glass transition temperature of PLA/TPU/PEG blends, so that the transition temperature of PLA/TPU/PEG blends can be adjusted to near human body temperature. PLA/TPU/PEG blends have excellent shape memory properties, their shape fixing rate decrease and the shape recovery rate increase with increasing PEG content. PLA-based three-way shape memory material has two glass transitions, and the two glass transition temperatures are greatly different. PLA-based three-way shape memory material has good three-way shape memory properties.