Insight into Chemical Recycling of Flexible Polyurethane Foams by Acidolysis

Abstract

Acidolysis is emerging as a promising method for recycling polyurethane foam (PUF) waste. Here, we present highly efficient acidolysis of PUFs with adipic acid (AA) by heating the reaction mixtures with microwaves. The influence of experimental conditions, such as reaction temperature, time, and amount of the degradation reagent, on the polyol functionality, molecular weight characteristics, the presence of side products, and the degree of degradation of the remaining PUF hard segments was studied by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS), nuclear magnetic resonance (NMR), size-exclusion chromatography (SEC) coupled to a multidetection system, and Fourier transform infrared (FT-IR) spectroscopy. The purified recycled polyols were used for the synthesis of flexible PUFs. The morphology and mechanical properties of the PUFs show that the degree of functionalization of the polyol by the carboxylic end groups, which is higher for larger amounts of AA used to degrade the PUFs, significantly affects the quality and performance of the flexible PUFs from the recycled polyols.

Green biobased P‐N coating: Towards waste‐minimization flame retardant flexible polyurethane foam

“…On the one hand, FPUF has a high potential fire hazard due to its flammable characteristics and particular use environment 4 . On the other hand, like most polymers, the service life of FPUF is not infinite, and the increasing number of FPUF is bound to cause a vast number of wasted FPUF that is difficult to degrade, resulting in severe environmental pollution 5 . Hence, researchers worldwide have made great efforts to solve the above issues.…”

“…Hence, chemical recycling, including glycolysis, aminolysis, and alcoholysis, has become the most employed technique for FPUFW recycling 29 . Now, acidolysis is emerging as the most promising recycling technology for FPUFW because it can recover single polyols with a high recovery rate 5 . Nevertheless, little attention has been paid to chemical recycling for FPUFW in the presence of flame retardants.…”

Chemical Recycling of Flexible Polyurethane Foams to Recover High Quality Polyols

“…Chemical recycling of polymers is an alternative to traditional methods of treating plastic waste (land ll, incineration, mechanical recycling) by converting them into feedstock suitable for re-polymerization into the same materials or into new materials of higher value (upcycling) [2][3][4] . Chemical recycling is particularly suitable for polymers with chemically labile groups in the backbone such as polyesters, polyamides, polyurethanes (PUs), and polycarbonates [5][6][7] . Depolymerisation of these polymer types is usually carried out by solvolysis using nucleophilic solvents in the presence of a catalyst.…”

“…Depending on the mechanism of urethane bond degradation, recycling technologies are mainly classi ed into hydrolysis 14,15 , (hydro)glycolysis [16][17][18][19][20][21][22][23][24] and, more recently, acidolysis 7,11,25−28 . To achieve e cient degradation of urethane groups, the process of PUF recycling must be carried out at high temperatures (200°C and above) by heating the reaction mixtures by conventional heating or, less commonly, by microwaves (MW) 7,17,29,30 , which allows an equally effective degradation process in a much shorter time. The high reaction temperatures required for e cient process highlight the importance of thermal degradation of urethane groups in PUF recycling 7,23 .…”

“…To achieve e cient degradation of urethane groups, the process of PUF recycling must be carried out at high temperatures (200°C and above) by heating the reaction mixtures by conventional heating or, less commonly, by microwaves (MW) 7,17,29,30 , which allows an equally effective degradation process in a much shorter time. The high reaction temperatures required for e cient process highlight the importance of thermal degradation of urethane groups in PUF recycling 7,23 . The general consensus is that the urethane groups start to thermally dissociate into the isocyanate and hydroxyl precursors above 150°C and in particular above 200°C 31,32 .…”