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
has a positive effect on the viscosity of the rebiopolyol obtained as a result of the
chemolysis reaction. As the biopolyol content increases, the viscosity decreases from
56,000 mPas (foam subjected to chemolysis without biopolyol) to 4,400 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 polyol were characterized by the highest degree of cell
openness. The content of closed cells had a direct impact on the mechanical
properties. The lower the closed cells content, the worse the 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.