Thermal degradation of polyether-urethanes: 5. Polyether-urethanes prepared from methylene bis(4-phenylisocyanate) and high molecular weight poly(ethylene glycols) and the effect of ammonium polyphosphate

Polyurethanes prepared by reaction of methylene bis(4-phenylisocyanate) with poly(ethylene glycols) with molecular weights of approximately 1000 and 1500 have been degraded thermally, alone and in the presence of ammonium polyphosphate (APP). Degradation has been carried out at temperatures up to 500°C and the volatile products and structural changes in the residue analysed in detail. From these data, comprehensive mechanisms have been deduced and discussed and the differences in absence and presence of APP emphasised.A brief general discussion of this and previous work on polyetherurethanes (PEU) is presented, which illustrates in particular the effect of the length of the polyether segment on the degradation reaction.