Recycling of rigid polyurethane foams via acidolysis

Abstract

The primary objective of this research is to advance our understanding of the recycling of polyurethane foams (PUF) through the process of acidolysis, with the specific focus on evaluating the potential of recovering rigid PUF waste. Drawing from the prior investigations on acidolysis of flexible PUF waste, we extended our research to the depolymerization of rigid PUF using succinic acid. The resulting recycled polyol (RP) exhibited comparable characteristics to the RP derived from flexible PUF. This similarity was confirmed by Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses, as well as by examining the hydroxyl number (OH_number) and acid value (AV) of the ensuing RP. Subsequently, rigid foams were produced using the RP as a partial replacement of the conventional polyol. The assessments of the PUF obtained revealed that this substitution did not compromise the morphology nor the physical properties of the foams. This was verified by scanning electron microscope (SEM) analyses, mechanical tests, and thermogravimetric analyses (TGA). In summary, our findings indicate that acidolysis is a viable method for recycling both flexible and rigid PUF, underscoring the growing significance of this recycling technique for the development of more sustainable materials.