Effect of Chemical Structure and Apparent Density of Rigid Polyurethane Foams on the Properties of Their Chemical Recycling Products

The aim of this work was to synthesize polyurethane foams based on petrochemical polyols and biopolyols with specific apparent densities (40, 60, 80, 100, and 120 kg/m³), test their properties, glycolyze them, and finally analyze each glycolyzed product. The petroleum-based foams, used as reference foams, and the bio-based foams underwent a series of standard tests to define their properties (the content of closed cells 20-95%, compressive strength 73-1323 kPa, thermal conductivity 24-42 mW/m∙K, brittleness 4.6-82.9%, changes in linear dimensions < 1%, and water absorption < 1%). Taking into account the need for recycling, the foams were shredded and then glycolyzed by diethylene glycol, with the addition of a catalyst in the form of potassium hydroxide. The chemolysis products were analyzed through determination, i.e., the amine and the hydroxyl values, viscosity, and molecular weight. The obtained rebiopolyols had hydroxyl numbers ranging from 476 to 511 mg KOH/g. The type of biopolyol used in the PUR foam systems had a significant impact on the amine number and the viscosity of the obtained rebiopolyol.