Photo-oxidative degradation of poly(p-dioxanone) under ultraviolet light source

The variations of structure and property of poly(p-dioxanone) (PPDO) in the process of photo-oxidative degradation and the mechanism of degradation were investigated in this work. The photo-oxidative degradation of PPDO was performed in air under ultraviolet light with two kinds of wavelength 365.0 nm and 253.7 nm. The extent of photo-oxidative degradation of the polymer was determined by morphological analysis, weight loss ratio, changes of viscosity and scanning electron microscope method (SEM). Infrared spectrometry (IR) and nuclear magnetic resonance (NMR) method were used to infer the mechanism of the photo-oxidative degradation. The changes of glass-transition temperature (Tg) and melting temperature (Tm) were characterized by differential scanning calorimetric (DSC) test. The morphological examination, IR and NMR testing revealed that the extent and mechanism of photo-oxidative degradation for PPDO are not closely correlated with its initial molecular weight. The main influence of initial molecular weight on the degradation is to change the ultimate distribution of the molecular weight. The conclusion is supported by the results of DSC test. All results from the research show the excellent photodegradable property of PPDO.