Impact of electron beam treatment on copolymers of polylactide and poly(trimethylene carbonate) in an air atmosphere

The effect of exposure of polylactide (PLA) and poly(trimethylene carbonate) (PTMC) statistical copolymers to ionizing radiation was studied by means of EPR spectroscopy. In addition, the influence of radiation-induced processes on thermal properties, miscibility of the components, weight average molecular weight (M-w) and number average molecular weight (M-n) were investigated for doses in the range of 0-200 kGy. In copolymers containing PLA and PTMC components in a ratio of 30:70 and 70:30 PLA radicals identified in the homopolymer under cryogenic conditions were dominant. This showed that PTMC radical centers either recombine or are transferred to PLA along the macromolecules. The results obtained for the non-irradiated and irradiated samples showed that the glass transition values measured by differential scanning calorimetry and calculated using the Fox equation were similar and indicated compatibility between the constituents of the tested copolymers and their miscibility. M-w and M-n changes measured by gel permeation chromatography were used to determine the radiation yield of scission G(S) and cross-linking G(X). In the case of PLA and PLA-rich copolymers, the difference between G(S) and G(X) with increasing dose increased, thus the chain scission predominated over cross-linking. For PTMC rich copolymer, the effect was opposite.

Automated summary

The study investigated the effect of ionizing radiation on polylactide (PLA) and poly(trimethylene carbonate) (PTMC) statistical copolymers using EPR spectroscopy, revealing that PLA radicals dominate in copolymers with ratios of 30:70 and 70:30 PLA and PTMC components. The results showed compatibility and miscibility between the components in both non-irradiated and irradiated samples, with chain scission predominantly over cross-linking in PLA and PLA-rich copolymers.