Characterization of thermoplastic interpenetrating polymer networks by various thermal analysis techniques

Thermoplastic interpenetrating polymer networks (t-IPNs), prepared by melting and pressing of crystallizable polyurethane (CPU) and styrene/acrylic acid random copolymer (S/AA) in wide ranges of composition, were investigated by the combination of various thermal analysis techniques: differential scanning calorimetry (DSC), thermomechanical analysis (TMA), thermally stimulated depolarization currents (TSDC) and thermally stimulated conductivity (TSC) measurements, as well as broadband dielectric relaxation spectroscopy (DRS). The results show that the t-IPNs under investigation are microheterogeneous systems with contributions to microheterogeneity from both the heterogeneity of the individual polymers and the thermodynamic incompatibility of the components.