MECHANICAL RELAXATION IN MISCIBLE POLYMER SYSTEMS - THE GLASS-TRANSITION REGIME IN POLY(VINYLMETHYLETHER) (PVME) CROSS-POLYSTYRENE (PS) SEMIINTERPENETRATING NETWORKS

Miscible semi-interpenetrating polymer networks (semi-IPN) of varying composition are prepared by crosslinking polystyrene containing few maleic anhydride groups with a diamine in the presence of linear poly(vinylmethylether) (PVME). The resulting PVME-c-P(ScoMA) semi-IPNs are characterized by their thermal and thermomechanical behaviour. Comparison with the corresponding uncrosslinked material proves that weak crosslinking has a negligible effect on the location of the glass transition as measured by d.s.c. Both the Tg data and the temperatures of the loss modulus maximum E″ (at 1 rad/s) show the same non-linear curved composition dependence. Contrary to this the tan δ maximum varies linearly with composition. These experimental results, in combination with frequency dependent measurements show that the temperature dependence of the mechanical response in the glass transition region is thermorheological complex. The results are interpreted by different segmental mobilities of PS and PVME chain segments in the glass transition region. © 1990.