Studies on the grafted polyurethane-polystyrene IPN's

Abstract

The grafted interpenetrating polymer networks (IPN``s) were prepared from the grafted polyurethane (based on polystyrene grafted poly (propylene glycol)) and polystyrene. The effect of improved compatibility on IPN morphology and properties was analyzed, by comparing these grafted IPN``s with regular polyurethane (based on poly(propylene glycol)) - polystyrene IPN``s. The morphology was studied by transmission electron microscopy. Both grafted and regular IPN``s showed heterogeneous morphology and showed phase inversion occuring somewhere between polyurethane 75% to 50% concentration. The grafted IPN``s had finer domain dispersions (as small as several hundred angstroms) than the regular IPN``s (about one thousand angstroms). The differences in the tensile properties, glass transition temperature and thermal stability were insignificant and did not show the effect of improved compatibility. But the hardness and density showed small effect. The enhancement in tensile strengths due to interpenetration was noted for both IPN``s but the effect of grafting was not noted in this study.