Molecular mobility and hydration properties in polyurethane and styrene-acrylonitrile blends

Dielectric measurements by means of thermally stimulated depolarization currents (TSDC) techniques in the temperature range 90-300 K were used to study molecular mobility and morphology in blends of polyurethanes based on branched polymer polyol (PUR) and styrene-acrylonitrile copolymer (SAN) with different SAN content. Water sorption/desorption isotherms both in equilibrium (ESI) and dynamic (DSI) were used to measure isothermal water uptake and diffusion coefficients. Water sorption has a significant influence on the /spl gamma/ and /spl beta/ relaxations. With increasing water content the MWS peak shifts to lower temperatures. For all samples studied the amount of water at saturation was found to decrease with increasing temperature and SAN content in the blends.