Degradation of aliphatic polyesters by vacuum ultraviolet irradiation

The degradation of aliphatic polyesters was investigated using the process of vacuum ultraviolet irradiation (VUV). The reaction mechanism, the effect of oxygen, and the application of an external electric field during irradiation were also investigated. VUV was generated using a Xe excimer with a center wavelength of 172 nm and the light intensity was 0.23 mW cm2. Infrared radiation (IR) for the polyester samples were measured on germanium substrates using a Jasco FT-IR-460 spectrometer. Ultraviolet spectra for the samples were measured on quartz glass substrates using a Jasco V-570 spectrometer. Aliphatic polymers such as PBS and PLA revealed a higher rate of degradation under VUV irradiation. It was also found that the activated species for degradation under VUV was negatively charged oxygen and the degradation by VUV light is 10% of that due to the activated species.