Interpenetrating polymer networks of 2-hydroxyethyl methacrylate terminated polyurethanes and polyurethanes

Interpenetrating polymer networks (IPNs) of 2-hydroxyethyl methacrylate ter minated polyurethanes (HPU) and polyurethanes (PU) with different ether-typ e polyols were prepared by simultaneous solution polymerization. Differenti al scanning calorimetry showed that the compatibility of polymers in IPN fo rmation depends on the molecular weight of the prepolymers. Compatible IPN systems resulted in greater-than-average density values and reduced swellin g behaviour. Water absorption of the IPNs was found to be mainly determined by the hard-to-soft segment ratio of the materials. The maximum tensile mo dulus occurred at a 25 wt% HPU content for the compatible systems and a 12. 5 wt% HPU content for those that were incompatible. The maximum tensile str ength occurred at a 25 wt% HPU content for all the TPN systems. Morphologic al observations using a scanning electron microscope revealed different fra cture surfaces between the compatible and incompatible systems. (C) 1999 El sevier Science Ltd. All rights reserved.