MULTIPHASE THERMOPLASTIC ELASTOMERS BY COMBINATION OF COVALENT AND ASSOCIATION CHAIN STRUCTURES .2. SMALL-STRAIN DYNAMIC MECHANICAL-PROPERTIES

Polybutadienes of narrow molecular-weight distribution, carrying statistically distributed polar phenylurazole (1), 4-ethoxycarbonylphenylurazole (2) and 4-carboxyphenylurazole (3) groups along the polymer chain, are analysed with respect to their dynamic mechanical properties in the linear viscoelastic region. In these systems thermoreversible networks are formed by hydrogen-bond complexes. In the case of 1 and 2, where only binary complexes are formed, the systems show thermorheologically simple behaviour, i.e. the construction of viscoelastic master curves is possible and the temperature dependence is described by an average apparent activation energy of flow for all relaxation processes. For polybutadiene carrying between 0.5 and 4 groups of 3 per 100 repeat units, thermorheologically complex behaviour is observed, which is related to the multiphase structure formed by phase separation between the covalent polybutadiene backbone and supramolecular ordered association polymers formed by the polar functional groups. © 1990.