Surface modification of polylactide films and their hydrolytic degradation performances in artificial seawater

Abstract

AbstractBenzophenone (BP) and N‐vinylpyrrolidone (NVP) were used to modify the surface of polylactide (PLA) films by UV grafting method. The effects of light distance, temperature, reaction time, and modifier concentration on the structure and properties of PLA films were investigated by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy (XPS), nuclear magnetic resonance spectroscopy, differential scanning calorimetry (DSC), and universal testing machine (UTM). With BP and NVP UV grafting, the hydrophilicity of PLA films is improved, but their thermal and mechanical properties are reduced under different surface modification condition. Base on the principle of good surface hydrophilicity, better mechanical and thermal properties, the hydrolytic degradation performance of modified PLA films in artificial seawater at 70°C was studied by scanning electron microscopy, XPS and DSC. The research results show that the degradation of modified PLA films mainly occurs in the amorphous region, and the degradation process conforms to surface hydrolysis mechanism. The grafting modification of NVP is better than BP to accelerate the degradation process of PLA films in artificial seawater. The degradation of modified PLA undergoes water molecule erosion and autocatalytic degradation reaction. The degradation of BP‐PLA obeys the first‐order kinetics in part, while the degradation of NVP‐PLA is more complex. Therefore, surface hydrophilicity modification is an effective technique for improving the degradability of PLA.