Hydrolytic degradation of nonoriented poly(β‐propiolactone)

Abstract

Abstract The hydrolytic degradation of poly(β‐propiolactone) with a molecular weight M w of 32,000 has been studied in a buffered salt solution (pH 7.2) at 37°C. Within 42 days, the embrittlement of the samples made tensile strength measurement impossible, which is due to the rapid reduction of molecular weight, 50% reduction after 49 days. The maximum weight due to water absorption was measured to 1.2 wt %, reached after 2 days. The absorbed water acts as a plasticizer in poly(β‐propiolactone) observed by the displacement in the maxima of the tan δ α peak. A fast increase of crystallinity in the samples has been observed during the first 50 days of degradation, with the increase continued up until 190 days, after which a decline of the crystallinity can be observed, indicating hydrolityc degradation of the crystalline part of the samples. The mass loss of the samples becomes prominent after 150 days of immersion and reached a value of 14.6% after 260 days.