RELAXATION BEHAVIOR OF INTERPENETRATING POLYMER NETWORKS BASED ON CROSS-LINKED POLYURETHANE AND WEAKLY CROSS-LINKED POLY(BUTYL METHACRYLATE) IN A WIDE FREQUENCY-RANGE

The frequency dependence of the dynamic shear modulus and mechanical l osses have been measured for interpenetrating polymer networks (IPNs) based on crosslinked polyurethane and weakly crosslinked poly(butyl me thacrylate) with component ratios (by weight) of 65/35 and 50/50. The frequency range used was 0.1-100 Rad s-1 over the temperature range fr om 133 to 413 K. According to the experimental data the IPNs have a tw o-phase structure with a segregation degree of 0.35-0.40. For each pha se the apparent activation energy has been determined and relaxation s pectra have been constructed using the method of reduced variables. Th e conclusion is that the relaxation behaviour of IPNs is dependent on the phase composition and morphological features.