Study of the synthesis and physical properties of fire-resistant polyurethane ionomers

Abstract

Fire-resistant polyurethane ionomers successfully synthesized at our laboratory have been proved by infrared spectra. In aqueous solution, the surface tension for fire-resistant polyurethane ionomers made by toluene diisocyanate or isophorone diisocyanate was found to decrease substantially with increasing concentration of 1,4-bis(2-hydroxyethyl)piperazine but to increase gradually with increasing phenylphosphonic acid or 1,4-bis(2-hydroxyethyl)piperazine with the phenylphosphonic acid concentration used to prepare these ionomers. For 1,4-bis(2-hydroxyethyl)piperazine-based polyurethane ionomers made by toluene diisocyanate or isophorone diisocyanate in aqueous solution, the number-average particle sizes of these ionomers decrease drastically with increasing 1,4-bis(2-hydroxyethyl)piperazine concentration, as a result of intramolecular interaction. On the other hand, for both phenylphosphonic acid and 1,4-bis(2-hydroxyethyl)piperazine with phenylphosphonic acid-based polyurethane ionomers, their average particle size increased with increasing phenylphosphonic acid or 1,4-bis(2-hydroxyethyl)piperazine 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 diisocyanate type than for the toluene diisocyanate type of fire-resistant polyurethane 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 polyurethane ionomers, the tensile strength at breaking point increases with increasing the concentration of fire retardants, but the elongation at breaking point for these ionomers, on the other hand, appears to decrease with increasing concentration of fire retardants.