Degradation behavior of polycarbonate during melt processing with an aqueous solution of sodium hydroxide

In this study, we aimed to enhance the reactivity of polycarbonate (PC) with the epoxy group of styrene-co-glycidyl methacrylate copolymer (SGMA) by introducing aqueous solutions of sodium hydroxide during the melt processing of PC. This approach led to the generation of hydroxyl groups at the ends of PC molecules, facilitating the formation of PC-SGMA copolymer. The effectiveness of this method in improving the compatibility of PC and styrene-acrylonitrile (SAN) blends was successfully confirmed through blending experiments with SAN and SGMA. Additionally, we investigated the impact of alkali-promoted hydrolysis on the rheological properties of PC, apart from the functionalization of PC end groups. Our findings revealed that an increase in the concentration of sodium hydroxide resulted in a decrease in the complex viscosity of PC. However, beyond a certain concentration level, the viscosity exhibited an upward trend. Furthermore, when constructing van Gurp-Palmen plots for the modified PC, we observed a significant deviation in curve shape compared to pure PC or water-modified PC. This observation suggests that changes in the microstructure occur during the degradation process due to the interaction between PC molecules and sodium ions.