Thermodestruction and thermooxidative destruction of polyurethanes

Abstract

Abstract It has been shown that the mechanism of destruction of the urethane group is determined by the structure of the starting components. The electron‐donating properties of the radical attached to the isocyanate group favor dissociation of the urethane group into isocyanate and alcohol, and electron‐accepting ones favor splitting of the urethane group into CO 2 and amines. The effect of the alcohol radical is quite contrary to the effect of the isocyanate radical: the electron‐donating properties of the radical favor splitting into CO 2 and amines, and the electron‐accepting ones favor dissociation of the urethane group into isocyanate and alcohol. The study of the effect of the foam‐forming catalysts on polyurethane destruction has shown that triethylenediamine and stannous dioctoate slightly accelerate the destruction processes. Being the catalyzer of the hydrolytic splitting, tin diethyl dicaprilate greatly accelerates the destruction in the presence of moisture only. It has been shown that urethane and urea groups of toluene diisocyanate polyurethanes improve the polymer stability toward thermooxidative destruction. In the course of the thermooxidative destruction of polyurethanes based on poly(oxypropylene) glycol the chain‐radical process of oxidation of the polyether unit of a macromolecule occurs.