A closed loop for polyurethane biofoams designed in line with the European Green Deal

Glycolysis is an efficient chemical degradation method allowing depolymerization of thermosetting rigid polyurethane foams into reusable monomers and oligomers. This study looks into a chemolysis of polyurethane biofoams containing different amounts of biopolyol (25-100 %) in the polyol premix. Increasing the biopolyol content in a foam had a positive effect on the viscosity of the rebiopolyol obtained as a result of the chemolysis reaction. As the biopolyol content increased, the viscosity decreased from 56,000 mPa s (foam subjected to chemolysis without biopolyol) to 4400 mPa s, which is by over 90 %. The foaming process was not affected in any significant way by different chemical structures of the rebiopolyols, as confirmed by, among others, FTIR and MALDI-TOF. The content of rebiopolyol in the system had a significant effect on the course of the foaming process, regardless the rebiopoyol structure. The rebiopolyol chemical structure has a significant impact on the content of closed cells of the newly-produced biofoams. The foams containing the rebiopolyols derived from the foams having more than 50 % of petrochemical polyol were characterized by the highest degree of cell openness. The content of closed cells had a direct impact on the foam mechanical properties. The lower the closed cells content, the worse the foam compression strength. However, it should be noted that open-cell foams are finding more and more applications. Thus, the effect observed in this study seems to be leading in a promising direction for the development of open-cell biofoams with the participation of rebiopolyols.