Degradation of biobased poly(ethylene 2,5-furandicarboxylate) and polyglycolide acid blends under lipase conditions

Abstract

Bio-based polymer materials are considered to have function of protecting the environment, and improving the degradation performance of bio-based polymer materials is of great significance to realize the green cycle of production-use-degradation of plastic products. This present work is focused on the investigation of the degradation behavior of bio-based polymer blend poly(ethylene 2,5-furandicarboxylate) /polyglycolide acid (PEF/PGA) with different composition ratios in phosphate-buffered saline (PBS solution, pH = 7.4) with 0.5 mg/mL of lipase from porcine pancreas. The results observed that the thermal decomposition temperatures at 5% weight loss of both the PEF/PGA blends are higher than 310°C, which reflected that the PEF/PGA blends possessed excellent thermal stability. The water absorption of the PEF/PGA blends continued to increase with increasing the PGA content. This trend is consistent with the mass loss of blends in the degradation process. The systematic degradation study revealed that the neat PEF showed no mass loss in both PBS solution with and without lipase, while the PEF/PGA blends possessed a faster rate under enzymatic degradation circumstance in the first 4 weeks, and the weight loss in the same degradation period increase with increasing the PGA content due to the erosion of lipase on the polymer chain. In particular, the weight loss of PEFGA40 blend was more than 18.33% after 8 weeks of degradation in enzyme solution. 1H NMR results showed that in addition to PGA component as a major component of degradation, a small amount of PEF component was also involved in the mass loss of the blend during degradation. At the same time, the short-chain segment produced during the degradation had a clear plasticizing effect on the PEFGA blends, which is reflected in that the Tg of PEFGA40 blend decreased first and then increased with the increase of degradation time.