Mechano-chemical rubber reclamation using aminolysis products of waste flexible polyurethane foams as the devulcanizing agent

Abstract

Rubber and polyurethane are polymers that are widely used but difficult to decompose in the natural environment. In this work, polyurethane aminolysis products (PAPs) are used to assist in the devulcanization of waste rubbers for the first time. The amine groups contained in PAPs can couple with the radicals generated by the scissions of crosslink bonds under the action of mechanical shear force, enhance the degree of devulcanization, and thus improve the mechanical properties of the reclaimed rubbers (RRs). The addition of PAPs can also shorten the optimum cure time of the RRs and improve the crosslink density and hardness of the RR re-vulcanizates. Using 1.8 phr of lower-layer PAPs prepared at 120 °C, the RR re-vulcanizate exhibit a tensile strength of 16.48 MPa, an elongation at break of 330.2%, and a tear strength of 48.5 MPa. This method realizes the dual high-value recycling of waste polyurethanes and rubbers, exhibiting bright application prospects.