Sustainable rigid polyurethane foams based on recycled polyols from chemical recycling of waste polyurethane foams

Abstract

The preparation and characteristics of rigid polyurethane foams (RPUFs) based on recycled polyol obtained by glycolysis of waste RPUF scraps from end-of-life refrigerators were investigated. To deactivate the amine adducts derived from isocyanates, the recycled product obtained after depolymerization was chemically modified via addition polymerization of propylene oxide. Two kinds of recycled polyols with different hydroxyl values and viscosity were blended with conventional virgin polyether polyol to prepare the RPUFs. The effects of the recycled polyols on the physical properties of RPUFs such as cell structures, compressive strength, thermal conductivity, and limiting oxygen index were discussed. It was found that the RPUFs from recycled polyols showed superior compressive strength, thermal insulation property, and selfextinguishing property compared with conventional control foam. The results of this study reveal that the recycled polyols could be used as feedstock for RPUFs with superior performance.

Recovery of Flexible Polyurethane Foam Waste for Efficient Reuse in Industrial Formulations

“…Borda et al performed the glycolysis of flexible polyurethane foams and elastomers with ethylene glycol, 1,2-propylene glycol, triethylene glycol, polyethylene glycol, and diethanolamine at 180 • C, and they also proposed a reaction mechanism [11]. Shin et al obtained a recycled polyol through the glycolysis of waste rigid polyurethane foams scraps, but this recycled product needed further chemical modification by addition polymerization with propylene oxide to deactivate the amine adducts derived from isocyanates [12]. The glycolysis process of rigid polyurethane foams was also carried out with basic catalysts using microwaves as energy sources, and the best results obtained were with potassium hydroxide and sodium hydroxide [13].…”

Synthesis of Rigid Polyurethane Foams Incorporating Polyols from Chemical Recycling of Post-Industrial Waste Polyurethane Foams

“…Regarding chemical recycling processes, using thermochemical or solvolysis reactions, such as glycolysis [ 8 , 9 , 10 ], aminolysis [ 11 , 12 , 13 ], alcoholysis [ 14 , 15 ] or hydrolysis [ 16 , 17 ], polymers are broken down into basic hydrocarbon units or monomers that can be used in the chemical industry as raw materials. Glycolysis is undoubtedly the most important polyurethane material recovery process with remarkable advances in all different classes of polyurethane, including rigid foams [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. The glycolysis of RPUFs (Equation (1)) consists of treating the residues with a low molecular mass glycol, thus obtaining a homogeneous, single-phase product with low viscosity and high hydroxyl value that can be used as a partial substitute for commercial polyether polyols in the synthesis of new rigid foams [ 25 , 26 ].…”

Thermally Remendable Polyurethane Network Cross-Linked via Reversible Diels–Alder Reaction

“…The synthetic design of recyclable materials is essential for sustainability, and there is a noticeable growth in the number of papers in the field in the last decade [1]. There are two ways to increase polyurethane sustainability: developing materials based on biorenewable sources such as lignin or sugars [3][4][5][6] and developing recycling technologies [7,8]. Generally, PU may be recycled by either destructive or nondestructive methods.…”