CHEMICAL RECOVERY OF POLYETHER POLYOLS FROM FLEXIBLE POLYURETHANE FOAM WASTES: CATALYST INFLUENCE

摘要

Polyurethanes represent one of the most important groups of plastics, so the increasing quantity of wastes makes its recycling an urgent task. The general purpose of polyurethane chemical recycling is to recover the polyol, a valuable raw material. Most of these processes yield a liquid mixture, which can only be used blended with raw materials to obtain middle quality products. Nevertheless, better quality products can be achieved from flexible polyurethane foams using a two-phase glycolysis. In this study, glycolysis reactions of flexible polyurethane foams in "split phase" were conducted with different glycols and catalysts, in order to study their activity and select a system which allows the obtaining of a quality recycled polyol. Reaction kinetics were investigated using GPC, glycolysis products were analysed by FT-IR and their properties measured according to standard methods. Diethylene glycol was probed to be the most suitable glycol to obtain a high quality recovered polyol. Diethanolamine and titanium butoxide showed a suitable catalytic activity. Times to reach complete conversion, chemical properties of the polyol phase and its purity depend on the glycol and catalyst employed. The recovered polyol obtained with DEG and DEA as catalyst has proved to be an economic alternative to organometallic catalysts as titanium compounds and presents good expectations to be successfully applied in new PU flexible foams synthesis.