Methods and applications for selective pyrolysis recovery of thermosetting polyurethane

Abstract

This invention relates to a method for selectively degrading and recovering thermosetting polyurethane and its applications. First, thermosetting polyurethane foam is mixed with a polar organic solvent and N-hydroxyphthalimide for a selective degradation reaction. The N-hydroxyphthalimide free radicals selectively attack the urea bonds in the polyurethane, causing them to cleave and yield degradation products with terminal hydroxyl and amino groups. These products are then melt-blended with polylactic acid to obtain a thermally conductive composite material, which is subsequently 3D printed to produce products of different shapes. Compared to existing polyurethane recycling methods, the N-hydroxyphthalimide used in this invention is non-toxic, harmless, inexpensive, and readily available. The organic solvent consumption is low and recyclable. Depolymerization products with controllable molecular weights can be obtained without expensive and complex separation and purification processes. This not only ensures the complete recycling and reuse of polyurethane solid waste resources but also achieves a high-value transformation from downgraded recycling to upgraded remanufacturing.

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