STUDY OF THE SYNTHESIS AND PHYSICAL-PROPERTIES OF FIRE-RESISTANT POLYURETHANE IONOMERS

Fire-resistant polyurethane ionomers successfully synthesized at our l aboratory have been proved by infrared spectra. In aqueous solution, t he surface tension for fire-resistant polyurethane ionomers made by to luene diisocyanate or isophorone diisocyanate was found to decrease su bstantially with increasing concentration of 1,4-bis (2-hydroxyethyl)p iperazine but to increase gradually with increasing phenylphosphonic a cid or 1,4-bis( 2-hydroxyethyl)piperazine with the phenylphosphonic ac id concentration used to prepare these ionomers. For 1,4-bis( 2-hydrox yethyl) piperazine-based polyurethane ionomers made by toluene diisocy anate or isophorone diisocyanate in aqueous solution, the number-avera ge particle sizes of these ionomers decrease drastically with increasi ng 1,4-bis(2-hydroxyethyl) piperazine concentration, as a result of in tramolecular interaction. On the other hand, for both phenylphosphonic acid and 1,4-bis (2-hydroxyethyl) piperazine with phenylphosphonic ac id-based polyurethane ionomers, their average particle size increased with increasing phenylphosphonic acid or 1,4-bis (2-hydroxyethyl)piper azine with phenylphosphonic acid concentration. This may be attributed to the results of intermolecular interaction. Obviously, the limiting oxygen index values are seen to be higher for the isophorone diisocya nate type than for the toluene diisocyanate type of fire-resistant pol yurethane ionomer. In fact, our experimental results suggest that the isophorone diisocyanate types of fire-resistant polyurethane ionomers provide good fire-resistance. For self-cured films of fire-resistant p olyurethane ionomers, the tensile strength at breaking point increases with increasing the concentration of fire retardants, but the elongat ion at breaking point for these ionomers, on the other hand, appears t o decrease with increasing concentration of fire retardants. (C) 1998 John Wiley & Sons, Inc.