Dielectric studies in homogeneous and heterogeneous polyurethane/polycyanurate interpenetrating polymer networks

Broadband dielectric relaxation spectroscopy and thermally stimulated depolarization currents techniques were employed to investigate molecular mobility in relation to morphology in semi-interpenetrating polymer networks (semi-IPNs) of linear polyurethane and polycyanurate networks (PCN) and in full sequential IPNs of crosslinked polyurethane and the same PCN. The semi-IPNs are found to be homogeneous at length scales larger than about 2 nm, whereas heterogeneity is suggested at shorter length scales. The full IPNs are characterized by microphase separation. The results are discussed in terms of the formation of chemical bonds between the components.