Polyurethane foam gets recycled

Abstract

Polyurethane films and foams are typically landfilled or “downcycled” into carpet padding. That might change: researchers have shown that they can re-form polyurethane for use in new products of similar commercial value to the original (ACS Cent. Sci., 2020, DOI: 10.1021/acscentsci.0c00083). Polyurethane is typically formed in an irreversible reaction catalyzed by dibutyltin dilaurate, which crosslinks the polymer chains when heated. The researchers found that adding more catalyst causes the reaction to go in both directions when the temperature is raised, allowing the polyurethane to be remolded, says Daylan Sheppard, a graduate student in William Dichtel’s lab at Northwestern University and lead author of the paper. The reverse reaction breaks only a few of the cross-links at a time, so the material never fully breaks down, Dichtel says. The team used a pair of turning screws to force out the excess air from foams as they extruded new filaments or films.