THERMOPLASTIC INTERPENETRATING POLYMER NETWORKS BASED ON A POLY(STYRENE-B-BUTADIENE) COPOLYMER AND AN IONICALLY-TERMINATED POLYBUTADIENE IONOMER

Thermoplastic interpenetrating polymer networks (IPN) are mixtures of two physically crosslinked polymers. Thermoplastic IPNs were prepared by blending an SBS triblock elastomer with a 1,2-polybutadiene that wa s ionically-terminated at both ends. The morphologies of these IPNs we re studied using differential scanning calorimetry and dynamic mechani cal thermal analysis. It was concluded that the ionomer was incompatib le with the SBS elastomer, since the T(g)s of both the 1,2-polybutadie ne from the ionomer and the essentially 1,4-polybutadiene from the SBS component were observable at temperatures that were close to those of the individual components. The addition of the polybutadiene material had, however, an influence on the relaxation processes of the polysty rene blocks. The polystyrene glass transition in the pure SBS copolyme r is broadened by the interfacial region between polystyrene and polyb utadiene. The low temperature shoulder was much more pronounced when t he ion-terminated polybutadiene was present, indicating it has a prefe rence to be located in these interfacial regions. (C) 1994 John Wiley & Sons, Inc.