Reviving recovered carbon black as a reinforcement for natural rubber by utilizing acylhydrazine-functionalized polysulfide as an intelligent interfacial modifier

Abstract

Recovered carbon black (rCB), a regenerative product from the thermal pyrolysis of waste tires, can be reused as a reinforcement for rubbers, with the goal of achieving high-value utilization of resources and promoting sustainable development. However, the inert surface of rCB causes poor compatibility with rubbers and results in low reinforcement efficiency. In this work, we synthesized acylhydrazine-functionalized polysulfide (SPT) and utilized it as an interfacial modifier for demineralized rCB (drCB)-filled natural rubber (NR) composites. SPT was synthesized through a one-pot sequential copolymerization of sulfur, styrene and thioctic acylhydrazine. The acylhydrazine moieties of SPT have multiple interactions with the oxygen-containing groups on the drCB surface, while the polysulfide segments are able to graft onto NR chains, thereby creating a molecular bridge between drCB and NR. Morphological and interfacial studies show that drCB dispersion is remarkably improved and interfacial adhesion is greatly enhanced upon the addition of SPT. As a consequence, the reinforcement efficiency of drCB is improved and the hysteresis loss of the resulting composites is significantly decreased.