Thermal degradation of polyether-urethanes: Part 3—Polyether-urethanes prepared from methylene bis(4-phenylisocyanate) and low molecular weight poly(ethylene glycols)

Polyurethanes have been prepared by reaction of methylene bis(4-phenylisocyanate) with diethylene glycol and with poly(ethylene glycol) with a molecular weight of approximately 200. Degradation has been carried out at temperatures up to 500°C and volatile products and structural changes in the residual polymer analysed in detail. The primary degradation reaction is one of depolycondensation to form the two monomers but a large proportion of these undergo a further complex series of reactions while they diffuse from the hot reaction zone. A comprehensive mechanism for the overall process has been deduced and discussed.