Thermoreversible and Recycling Properties of Ethylene Propylene Diene Rubber Based on Diels-Alder Reaction

The preparation and properties of thermoreversible ethylene propylene diene rubber (EPDM) based on reversible Diels-Alder reaction were investigated. The reversible cross-linking ethylene propylene diene rubber was prepared by a two-step method. The EPDM which was grafted with maleic anhydride (MA) was firstly modified by furfurylamine to graft furan groups on rubber backbone, and then crosslinked with bismaleimide (BMI) via a Diels-Alder reaction. At room temperature, thermoreversible cross-linking EPDM exhibited excellent mechanical properties. The molar ratio between BMI and MA was studied, and it was found that too high and too low ratios were not conducive to the formation of high cross-linking density network. When the molar ratio between BMI and MA was 0.9, the cross-linking EPDM had the best mechanical property, with tensile strength of 2.3 MPa and the elongation at break of 312%. The dynamic mechanical analysis and dissolution experiments showed that the reversible Diels-Alder reaction at high temperatures led to the de-crosslinking of rubber networks. Despite the presence of a small number of side effects, the EPDM obtained by Diels-Alder reaction showed a better reshaping ability, and it could be recycled several times.