Rebiopolyols – New components for the synthesis of polyurethane biofoams in line with the circular economy concept

Abstract

The primary goal of the research presented here was to evaluate the possibility of chemolysis of polyurethane biofoams synthesized from vegetable oil-based biopolyols with different chemical structures. As a reference material, a foam synthesized in 100 % from a petrochemical polyol was used. Chemolysis of polyurethane foams was conducted by using diethylene glycol as a solvent with a 1.5:1 wt ratio of biopolyurethane scraps to glycol. The reaction was carried out at 180 °C for 100 min in the presence of potassium hydroxide as a catalyst. The results of the chemolysis of different polyurethane foams were evaluated in terms of the hydroxyl number, amine value, viscosity, molecular weight and FTIR analysis of the new rebiopolyols. It can be concluded that the chemical structures of different biopolyols (obtained through the method of transesterification of vegetable oils with two different reagents and a two-step method of epoxidation and oxirane rings opening) that are used to make biopolyurethane foams have an impact on the course of the chemolysis process and the properties of resultant rebiopolyols.In order to verify the application possibilities of the new components obtained in accordance with the idea of circular economy, extreme conditions were applied in the form of complete replacement of the polyol in the reference foam with the rebiopolyols. It was found that replacing the petrochemical polyol with the repolyol results in partial cell opening, and replacing this component with the rebiopolyols results in open-cell foams. Only the rebiopolyol derived from the biofoam with the biopolyol obtained by transesterification of oil with triethanolamine was not suitable for use in a polyurethane system because its reactivity was too high. In conclusion, there is no need to use catalysts to obtain new biofoams from rebiopolyols given the catalytic nature of the new biocomponents.