Influence of crystallization on the shape memory effect of poly (lactic acid)

The objective of this study is to investigate the influence of crystallization on the shape memory effect (SME) of poly (lactic acid) (PLA). Different thermal treatment times were applied to the PLA to obtain different degrees of crystallinity. Additionally, a PLA sample was cooled rapidly to obtain an amorphous PLA. The characterization techniques used in this study were Fourier transform infrared spectroscopy, x-ray diffraction, Dynamic Mechanical Analysis, the differential scanning calorimetry, optical microscopy, and the SME was evaluated by fold-deploy and torsion modes. Results show that crystallization positively affected the SME, both in shape fixity and shape recovery. Different crystallization times provided different degrees of crystallinity, and the SME gradually increased with increasing crystallinity. Additionally, it was found that the SME of PLA is higher in water. The study concludes that the crystallization process plays a crucial role in the SME of PLA, and this work contributes to the understanding of the relationship between crystallization and the SME of PLA, which can contribute to the development of new technologies and applications for shape memory polymers.