Chemical Recycling of Flexible Polyurethane Foam Scraps Using Bio-Based Acidolysis Agents

Acidolysis is emerging as an industrial way to recycle chemical polyurethane foam (PUF) waste. This study developed a green and economical route for the chemical recycling of flexible PUF scraps by a virgin polyol-free acidolysis process. Ricinoleic acid (RA) derivatives synthesized from RA and anhydrides as a long-chain dicarboxylic acid (DA) were considered to investigate dangle-side chains' effect and molecular weight on PUF acidolysis. Prepared DAs were used as a biobased, renewable, and eco-friendly acidolysis agent. The thermoset PUF was efficiently fragmented into small molecules and oligomers with hydroxyl groups via DAs. Chemical structures of recycled polyol (RP) were identified by Fourier transform infrared (FTIR) spectroscopy, Nuclear Magnetic Resonance (NMR) spectroscopy, and gel permeability chromatography (GPC). The acquired RPs possess suitable industrial traits, such as hydroxyl number, acid number, and viscosity, for producing flexible PUF. RPs can substitute up to 30% virgin polyol in the production of flexible PUF while preserving the mechanical properties of RPUFs to pass commercial standards. This study shows a valuable acidolysis process with a biobased acidolysis agent, which promoted the industrialization of flexible PUF chemical recycling. The suggested flexible PUF recycling process will help a circular economy and sustainability and will grow the recycling rate of flexible PUFs in the polyurethane industry.