Thermal behavior, morphology, and some melt properties of blends of polycarbonate with poly(styrene‐co‐acrylonitrile) and poly(acrylonitrile‐butadiene‐styrene)

Blends of bisphenol‐A polycarbonate (PC) with poly‐ (styrene‐co‐acrylonitrile) (SAN) and poly (acrylonitrile‐butadiene‐styrene) (ABS) prepared by screw extrusion and solution‐casting were investigated by differential scanning calorimetry and scanning electron microscopy. From the measured glass‐transition temperatures (T_g) and specific heat increments (ΔC_p) at the T_g, SAN appears to dissolve more in the PC‐rich phase than does PC in the SAN‐rich phase. Also, the decrease of T_g (PC) in PC/ABS blends is larger than in the PC/SAN blends. From the T_g behavior and the electron microscopy study, it is suggested that the compatibility increases more in the SAN‐rich compositions than in the PC‐rich compositions of the blends. In the study of extrudate swell of the PC/SAN blends and the PC/ABS blends, the maximum level of extrudate swell is reached at 0.5 weight fraction of PC for both blend systems. The Flory‐Huggins polymer‐polymer interaction parameter (χ12) between PC and SAN was calculated and found to be 0.034 ± 0.004. A similar value of χ for PC and SAN was found with the PC/ABS blends.