The effect of styrene-methyl methacrylate block copolymers on the interfacial tensions between (poly(phenylene oxide)/polystyrene) and poly(styrene-co-acrylonitrile)

The effect of styrene-methyl methacrylate block copolymers on the interfacial oxide)/polystyrene) (PPO/PS) and poly(styrene-co-acrylonitrile) (SAN) was examined by the imbedded fiber retraction (IFR) method. It was found that the interfacial tension between (PPO/PS) and SAN decreases with increasing the amount of the block copolymer and the block copolymer containing longer PMMA block is more effective in reduction of interfacial tension than the block copolymer of shorter PMMA block. When the block copolymers were added into SAN fiber, the reduction in interfacial tension was larger as compared with the case when the block copolymers were added to the (PPO/PS) matrix. These results were very consistent with the results of SEM observations: more regular and finer dispersion was observed when the block copolymers were added to the blend system.