Recycling of Polyurethane Polymers

Abstract

Thermoset polyurethane polymers, such as rigid and flexible foams, elastomers and RIM-PUR can be recycled. A lot of processes have been developed, based on physical and chemical methods, which produce materials that can be directly or indirectly reused in the production of new polyurethanes. Physical recycling methods (primary and secondary recycling), including recycling of material as filler, flake and particle rebonding and hot compression molding, have found different applications, especially in the field of flexible foams and RIM-PUR. Chemical recycling methods (tertiary recycling), such as hydrogenation, hydrolysis, glycolysis and pyrolysis seem to be more interesting, as they are able to assure a high recovery of these materials. In particular the glycolysis process has been dealt with in depth as it seems to be the most promising in versatility and cheapness among the different chemical processes. Incineration with thermal recovery (quaternary recycling) is a possible last stage operation for those materials that cannot be recovered in other ways. These recycling technologies contribute to overall energy savings and eliminate the cost and ecological problems of landfill.