Effect of interfacial tension on the cell structure of poly(methyl methacrylate)/bisphenol A polycarbonate blends foamed with CO2

Abstract

A small amount of low‐decomposition temperature poly(methyl methacrylate), (low‐Td PMMA), can be used as a compatibilizer for high‐decomposition temperature PMMA (high‐Td PMMA) and polycarbonate (PC) blend systems. When low‐Td PMMA is thermally decomposed in the PMMA/PC blend, the PMMA‐g‐PC copolymer is formed. This copolymer decreases the interfacial tension between PMMA and PC, decreases the domain size of PC and increases the interfacial area. Blends of high‐Td PMMA/PC with different amounts of low‐Td PMMA undergo a batch physical foaming with CO2. With increasing amounts of low‐Td PMMA, which is equivalent to increasing the PMMA‐g‐PC copolymer, the number density of bubbles increases due to the increase of the interfacial area of disperse domains. However, the interfacial tension is decreased and the heterogeneity of PMMA/PC blend is decreased with increasing amounts of the copolymer. The number of bubbles per unit interfacial area and that per unit number of domains are decreased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39228.