Reprocessing and Upcycling of Mixed Polyurethane Waste Streams

Polyurethanes (PUs) are used in bedding, furniture, and as thermal insulation, comprising 31% of the thermoset market ($48B in 2015). PU foams contain voids and take up disproportionate space in landfills for their weight. Unlike thermoplastics, PUs traditionally cannot be meltprocessed, and chemical cross-links preclude repairing or reshaping cross-linked PUs. Urethane chemistry is also not traditionally amenable to recycling, as even thermoplastic PUs degrade and lose performance at the required temperatures. Some flexible PU foams are mechanically downcycled into carpet rebond, but the chemical recycling of PU waste often provides products with deteriorated mechanical properties and limited utility. Rigid PU foams and cross-linked elastomers are recycled even more rarely. Therefore, developing methods to recycle or upcycle PU foams and elastomers represent an important opportunity to improve their circularity and sustainability.