Sustainable recycling of flexible polyurethane foams: chemolysis via anhydrides

The purpose of this work is the recycling of flexible polyurethane foams via chemolysis with anhydrides, an innovative process compared with the classical chemical recycling methods. Tests carried out include the use of various anhydrides. However the work is mainly focused on the succinic anhydride since the results obtained with it are the most promising, especially in terms of MDA (4,4' - Methilendianilina) abatement. The variables analyzed are the amount of exploited anhydrides in relation to the quantity of waste to be recycled, the operating temperatures and the formation and processing of unwanted by-products. A recycled polyol characterization (viscosity, MDA content, hydroxyl and acid number) is essential to be able to reintegrate it in new formulation: the production of new foams containing increasing percentages of recycled polyol will therefore fully represents the concept of circular economy.