Recycling of flexible polyurethane foam wastes of automotive parts by acidolysis

With the aim to minimize the quantity and disposal of the polyurethane foam waste residue, depolymerization of polyurethane (PU) waste scrap via acidolysis using dicarboxylic acids (DA) was successfully attained. PU flexible foam waste was recycled using different dicarboxylic acids, namely succinic and phthalic dicarboxylic acids, as the cleavage agent and polyol as a conventional solvent. The effect of reaction temperature on the conversion and properties of the recovered polyol (RP) was investigated. The degradation of PU foams and formation of reaction products was confirmed using Fourier-transform infrared spectroscopy. Phthalic acid as a cleavage agent resulted in higher conversion and single-phase recovered polyols, whereas succinic acid yielded split-phase polyols. Phthalic acid-based recovered polyol has higher viscosity than succinic acid-based recovered polyol. Finally, the recovered polyol was used as a partial substitute for virgin polyol (up to 10%, w/w) for the preparation of regenerated polyurethane foam (RPUF). The RPUF showed similar cell-size morphology and foaming properties to that derived from the virgin polyol. The comfort properties of the RPUF with respect to sag factor, hardness, and hysteresis loss displayed comparable values to that of virgin foam. Overall, the applicability of this method for the recycling of PU foam waste via acidolysis was illustrated, and the recovered polyol can be used as feedstock for foam preparation with comparable performance.