Recycling of Flexible Polyurethane Foams by Regrinding Scraps into Powder to Replace Polyol for Re-Foaming

Abstract

In the context of protecting the ecological environment and carbon neutrality, high-value recycling of flexible polyurethane foam (F-PUF) scraps, generated in the production process, is of great significance to save petroleum raw materials and reduce energy consumption. In the present study, F-PUF scraps were ground into powder by strong shear regrinding using two-roll mill and then reused as a partial replacement of polyol for re-foaming. A series of characterizations were employed to investigate the effect of milling cycles, roller temperatures, and content of the powder on the properties of the powder and F-PUF containing powder. It was revealed that the mechanochemical effect induced breaking of the cross-linking structure and increased activity of the powder. The volume mean diameter (VMD) of powder prepared with 7 milling cycles, at room temperature, is about 97.73 μm. The microstructure and density of the F-PUF containing powder prepared in the above-mentioned manner to replace up to 15 wt.% polyol, is similar to the original F-PUF, with resilience 49.08% and compression set 7.8%, which indicates that the recycling method will play an important role in industrial applications.

Impact of Sunflower Press Cake and Its Modification with Liquid Glass on Polyurethane Foam Composites: Thermal Stability, Ignitability, and Fire Resistance

“…Polyurethane (PUR) foams are an important group of polymers with many advantageous applications in various industries, such as for furniture, consumer bedding, automotive seats, cushioning, medicine, thermal insulation, sound absorption, and in specific locations where other materials would not be suitable because of the versatile chemistry of these products [ 1 , 2 ]. PUR is generally developed through the polyaddition reaction between isocyanates and polyols with other additives to improve the cellular structure and foaming [ 3 ]. The materials for the production of PURs are mainly from petrochemical feedstocks, whose usage is currently becoming unpopular because of the increasing environmental awareness and demand for a cleaner environment [ 4 , 5 ].…”

Opportunities in Closed-Loop Molecular Recycling of End-of-Life Polyurethane

“…14,15 While PU waste can be recycled by mechanical methods such as cutting, grinding, and tearing, mechanically recycled material cannot be reassembled into new plastic products. 16 Because PU is a thermoset, it cannot be remolded. Thus, the materials made from mechanically recycled PU waste are low-value products with limited applications.…”

“…Landfilling, however, abandons any value in end-of-life PU waste and requires virgin precursors be used in all newly produced PU products . To realize the valorization of PU waste, mechanical, biological, and chemical recycling methods have been investigated. , While PU waste can be recycled by mechanical methods such as cutting, grinding, and tearing, mechanically recycled material cannot be reassembled into new plastic products . Because PU is a thermoset, it cannot be remolded.…”

Single-Phase Recycling of Flexible Polyurethane Foam by Glycolysis and Oxyalkylation: Large-Scale Industrial Evaluation

“…Recently, acidolysis and glycolysis approaches have been introduced for the recycling of PUFs at an industrial scale. − However, these approaches suffer from limitations such as phase separation between the polyol and methylene diphenyl diisocyanate (MDI) compounds and partial/nonselective degradation of the urethane linkages, which lower the industrial yield of the process. In addition, the glycolysis method requires additional treatment steps for residual amines derived from isocyanates because of their undesirable odor, high reactivity, and influence on the physical characteristics of PUFs .…”