A facile strategy for high mechanical performance and recyclable EPDM rubber enabled by exchangeable ion crosslinking

Endowing rubber with excellent recycling ability is of great significance for energy conservation. It is still a huge challenge to obtain high-performance recyclable commercial rubber to satisfy practical applications. Herein, a facile strategy of incorporating exchangeable Zn2+-carboxyl crosslinks into commercial EPDM system was developed through reaction of zinc acetate and EPDM grafted maleic anhydride (EPDM-g-MAH) to obtain EPDM-g-MAZn. The constructed exchangeable crosslinking networks as sacrificial unit significantly enhanced mechanical properties of EPDM, much higher than EPDM cured by covalent bonds (tensile strength: 2.00 MPa and fracture toughness: 6.75 MJ/m(3)). The dynamic crosslinking was reversibly broken and reformed by hot pressing, endowing EPDM-g-MAZn with good recycling ability. The promising mechanical properties of EPDM-g-MAZn can be tailored by incorporation of carbon black (CB) or zinc dimethacrylate (ZDMA), and recycled EPDM-g-MAZn/CB exhibited good mechanical properties to meet industrial applications. Additionally, multiple cross-linking networks were constructed for EPDM-g-MAZn/ZDMA with fine dispersion of ZDMA due to Zn2+-carboxyl interactions. Such effective strategy exhibits a promising perspective in industrial applications of high -performance recyclable rubber field.