Synthesis, characterization and properties of novel poly (urethane-imide) networks as electrical insulators with improved thermal stability

A new series of thermoplastic poly(urethanein-imide)s (TPUI1-4) containing hydroxyl groups in the backbone was synthesized from the reaction of epoxy-terminated polyurethane prepolymers (EPU1-4) and an imide containing diacid (DIDA) chain extender under optimized reaction conditions. EPU1-4 was prepared through end-functionalization of NCO-terminated polyurethanes based on polyester polyol (CAPA) and hexamethylene diisocyanate with glycidol. A blocked isocyanate (BIC) was made from the reaction of trimethylol propane (TMP), toluene diisocyanate (TDI) and N-methylaniline (NMA). Polymer networks were prepared from the reaction of librated isocyanate groups of BIC with hydroxyl groups of TPUIs. The starting materials and polymers were characterized by conventional spectroscopic methods and the physical, thermal and electrical properties of crosslinked networks were studied. Investigation of the recorded properties for these samples showed considerable improvement in thermal and electrical properties in comparison to common polyurethanes. [GRAPHICS] Synthetic route for preparation of TPUIs.