Imide-modified polyurethanes, syntheses, thermal, imide-modified polyurethanes, and mechanical characteristics

Polyurethanes based on polyethylene glycol and hydroxy-terminated polybutadiene, bearing pyromellitimide groups in the backbone, were synthesised via a sequential method. The diisocyanate and diamine telechelic precursor polymers, the polyamic acid intermediate and the polyimides were characterized by physicochemical and thermoanalytical techniques. The imide content could be varied in the chain through selection of the polyol of desired molecular weight or by a chain extension process of the diisocyanate precursor. The thermal and mechanical properties of the imide-modified polyurethane increased proportionate to the hard segment content, constituted by the imide and the urea groups. The presence of the imide group resulted in better thermomechanical profile and caused enhancement in glass transition temperature of the modified polyurethane vis-a-vis the unmodified resin. (C) 1998 John Wiley & Sons, Inc.