Glycolysis of Flexible Polyurethane Foams

Abstract

Flexible water blown polyurethanes are polymers with repeating urethane and urea groups. When they undergo heating in the presence of glycols the reaction of these groups leads to soluble products. The transesterification reaction of the urethane groups, that leads to the formation of new carbamate is faster than that of the urea groups. Carbamates in turn undergo aminolysis due to the amines formed in the glycolysis of the urea groups. The use of ethylene glycol (EG) allows the process to be carried out with high polymer/glycol ratio (up to 4:1). A polyphase product is obtained with a top liquid phase mainly formed by the polyether polyol from the polymer, an intermediate liquid phase formed by the solution of carbamates, ureas and amines in EG and a bottom solid phase with compounds with prevalent urea bonds.