Crack healing and reclaiming of vulcanized rubber by triggering the rearrangement of inherent sulfur crosslinked networks

Abstract

CuCl₂ has been shown to effectively catalyze reshuffling of the inherent sulfur crosslinked networks of vulcanized rubber. Once activated, CuCl₂-based complex catalysis enables disulfide metathesis through circulated crossover reactions among disulfide and polysulfide bonds without forming radicals and ionic intermediates. By taking advantage of this mechanism, the model material of this study, vulcanized polybutadiene rubber, acquires thermal remendability as characterized by repeated restoration of mechanical properties. Moreover, it can be reprocessed like thermoplastics. The compositions and fabrication of the model material simulate those of industrial vulcanized rubber, so as to facilitate formulation optimization under the circumstances close to the actual situation for possible future practical applications. It is hoped that the results of the present preliminary exploration would provide the basis for extending the service life and developing new recycling techniques of vulcanized rubber, which is produced, used and scrapped in large quantities every day.