In Situ Constructed Nanocrystal Structure and Its Contribution in Shape Memory Performance of Pure Polylactide

Crystal size plays an essential role in the performance of polymers. Generally, direct processing of common spherulites into nanocrystals (NCs) is hardly applied since polymer spherulites always shape into fibrous crystals and are hard to flow again. In this study, polylactide (PLA) lamellae of spherulites are first diluted by amorphous PLA. Then, PLA NCs are constructed in situ by intense stress, which is transferred by the amorphous polylactide in a high elastic state. The NCs and their network formed in bulk endow pure polylactide with excellent shape memory features. A strong shape recovery initiation force (around 4-5 MPa) and an enhancement of 41.6% in the shape recovery ratio with 30 wt % NCs in PLA are achieved compared with traditional PLA. This study presents a new common methodology for the industrial production of polymer NCs.

Automated summary

This study demonstrates a new common methodology for industrial production of polymer NCs, by diluting spherulites with amorphous PLA and constructing NCs in situ through intense stress, resulting in improved shape memory features of pure polylactide.