Effect of gamma-irradiation on hydrolysis of commercial poly(L-lactide) at elevated temperature

• Published in: Polymer degradation and stability Vol. 206; p. 110202
• Main Authors: Fedorenko, Alexandra A., Grinyuk, Evgeny V., Salnikova, Iryna A., Kostjuk, Sergei V.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2022
• Subjects: Degradation; Hydrolysis; Irradiation; Polylactide; Hydrolysis; Degradation; Irradiation; Polylactide
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2022.110202

•Preliminary irradiation accelerates poly(L-lactide) hydrolysis.•Irradiated poly(L-lactide) crystallizes at higher rate during hydrolysis.•Radiation treatment may eliminate induction period during polymer degradation. The present study aimed to examine the effect of gamma-irradiation on subsequent hydrolytic degradation of poly(L-lactide) (PLLA) and polymer crystallization behavior during this process. Absorbed doses were 29 and 75 kGy, unirradiated sample was also studied. Hydrolysis was performed at 60 °C for up to 50 days. Radiation treatment of PLLA accelerates hydrolysis process. It affects polymer mass loss, molecular weight distribution, change of hydrolysis media pH, and values of the hydrolytic degradation rate constant. Preliminary irradiation makes it possible to eliminate the induction period of PLLA mass loss during hydrolysis. However, a decrease of polymer molecular weight during irradiation leads to an increase of PLLA crystallization rate upon hydrolysis. It was found that α crystals can be formed during hydrolytic degradation. Parameters of PLLA unit cell were calculated. When polymer degree of crystallinity becomes high enough its hydrolytic degradation slows down. Thus, faster crystallization of irradiated PLLA reduces the acceleration effect of radiation treatment on polymer hydrolysis. [Display omitted]