Recycle of Flexible Polyurethane Foam by Acidolysis and Reuse of Recovered Polyol

Polyurethane foam (PUF) is one of the most widely used polymers and accordingly large quantities of waste materials reveal globally. In this study, chemical recycling method based on acidolysis by dicarboxylic acids using a mixture of unsaturated maleic acid and saturated phthalic acid was used to cleave urethane bonds and produce recycled polyol (repolyol). Effects of the reaction temperature (190 °C, 220 °C), stirring speed (400 rpm, 500 rpm), and reaction time (6 h, 12 h) on the hydroxyl number, water content, viscosity, and acid number of the repolyols were tested. FTIR (Fourier Transform Infrared) and TGA (Thermogravimetric Analysis) techniques were employed to compare the properties of the obtained repolyols with reference polyol. The repolyols were then used at 10–50 wt% as substitute of reference polyol to produce flexible polyurethane foam (FPUF). The produced foams were analyzed by optical microscopy and TGA techniques, and the density, hardness, air permeability, compression set, resilience, and tensile strength characteristics were tested. The analysis results of the FPUFs containing repolyols were compared with those of the reference foam. It was concluded that the obtained polyol can be safely used up to 20 wt% to produce FPUFs. However, further increase in repolyol ratio led to reduction in air permeability, compression set, and resilience performance of the produced FPUFs.