Regeneration of Polyol by Pentaerythritol-assisted Glycolysis of Flexible Polyurethane Foam Wastes

The aim of this work is to introduce a novel chemical recycling approach for polyurethane foam wastes which can produce useful chemicals. Flexible polyurethane foam was dissolved in a mixture of diethylene glycol (DEG) and pentaerythritol (PE). PER is a useful choice in recycling processes because of its OH functional groups and its structural similarity to polyols. Meanwhile, there are several environmental advantages for chemical recycling of polyurethane foam wastes due to the capabilities of the above method. The trans-esterification process cleaves the urethane structure, producing OH containing chemicals. The product is separated in 2 phases which are both useful in the production of new PU foams. The split product was characterized by several analytical methods, e.g., chromatography and spectroscopy. Optimum reaction condition and the role of recycled polyol on foam properties were investigated, as well. The solvent system contained DEG/PER as 9/1 ratio. Sodium hydroxide was used as the catalyst and the optimum reaction time was 4 h. Separated phases of the product are reusable in polyurethane foam formulation: upper phase in flexible (40%) and lower phase in rigid (30%) foams to obtain desirable physical properties in the final product. This method can be introduced as a route for reduction of environmental hazardous materials, while regenerating valuable raw materials.