THERMOPLASTIC INTERPENETRATING POLYMER NETWORKS BASED ON A POLY(STYRENE-B-BUTADIENE) COPOLYMER AND A POLY(STYRENE-CO-SODIUM METHACRYLATE) IONOMER

Thermoplastic interpenetrating polymer networks (IPN) are blends of tw o physically cross-linked polymers. These thermoplastic IPNs were prep ared by melt blending an SBS triblock elastomer with a poly(styrene-co -sodium methacrylate) ionomer. Dynamic mechanical thermal analysis, el ectron microscopy and stress-strain analysis were used to probe the mo rphology of a range of compositions to assess the influence of mixing conditions, copolymer composition, molecular weight and degree of neut ralization on morphology. These thermoplastic IPNs showed clear phase separation. The best mixing occurred under conditions where the two co mponents were as near as possible to being isoviscous. Neutralization caused significant changes in morphology. The interpenetration of phas es is clearly evident.