Miscibility and deformation behavior in some thermoplastic polymer blends containing poly(styrene‐co‐acrylonitrile)

Abstract

Abstract Miscibility in blends of poly(styrene‐co‐acrylonitrile) (PSAN) with several other polymeric components has been investigated over a range of compositions by means of thermal analysis and transmission electron microscopy. Systems in vestigated were (i) PSAN/polycarbonate (PC), (ii) PSAN/styrene‐maleic anhydride‐methyl methacrylate terpolymer (S/MA/MM), (iii) PSAN/polynorbornene nitrile (PNN), and (iv) PSAN//S/MA/MM//PC. PSAN/PC was demonstrated to be partially miscible in all proportions over the PSAN copolymer composition range 23–70 wt % AN, while the miscibility or lack thereof of PSAN//S/MA/MM depended on the relative AN and MA contents of the PSAN and S/MA/MM, respectively. In contrast, PSAN/PNN was found to be immiscible in all proporations, while the system PSAN//S/MA/MM//PC was shown to be partially miscible. Deformation studies performed on rubber‐modified versions of these blends defined deformation mode and microstructural deformation behavior. Dual extensometer tensile testing yielded relative contributions of crazing and of plastic flow, which correlated both with blend composition and with toughness. TEM observations of deformed specimens indicated a deformation process in the multiphase matrix blends consisting of craze initiation and propagation in the rubber‐containing phase, craze arresting in the ductile second matrix phase, and coordinated extensive deformation of the matrix phases and of the rubber particles, where the ability to support the latter coordinated forms of deformation were observed to increase with increasing proportion of plastically deforming phase.