LAUSR

Split-phase alcoholysis of flexible polyurethane (PU) foam yields an apolar phase containing the recycled polyether polyol, and a lower, polar phase of the alcoholyzing agent and aromatic compounds. However, multiple purification steps are required to render the polyether polyol suitable for synthesis of new flexible PU foams; the unfavorable mass balance limits industrial applications. In this work, 2-pyrrolidone was identified as a performant additive for accelerating the dissolution and depolymerization process. By applying a lactam to PU foam weight ratio of 0.1:1, the glycol to PU foam weight ratio can be decreased from 1.5:1 to only 0.5:1, without loss of purity or yield of the recycled polyether polyol. Diglycerol was discovered as a novel, promising alcoholyzing agent; it allows to recycle the polyether polyol in high purity (97%) and excellent yields (98%), and after a single washing with diglycerol, a sufficiently low hydroxyl value (61 mg KOH/g) is reached. The recycled polyether polyol can replace the virgin polyether polyol (48 mg KOH/g) for up to 50% in the synthesis of new flexible PU foams with effects on the foam quality that stay within the limits of generally accepted specifications. A first step towards the valorization of the lower phase was also taken by hydrolysis of the newly formed carbamates to toluenediamines, which are readily reintegrated in new PU foams.