Basic Studies of Continuous Ultrasonic Devulcanization of Rubbers

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9312249 Isayev The main objective of the project is to develop basic knowledge for a new science-based technology of continuous devulcanization of vulcanized elastomers. It is well known that vulcanized elastomers having a three-dimensional network cannot flow under the effect of heat and/or pressure. It has been discovered that through the application of certain levels of ultrasolic amplitudes in special devices in the presence of pressure and optionally heat, the three-dimensional network of vulcanized elastomer can be broken down within a short period of time on the order of one second or less. As a most desirable consequence, ultrasonically treated vulcanized rubber becomes soft, thereby enabling this material to be reprocessed, shaped, and revulcanized in a manner similar to that employed with unvulcanized elastomer. The study outlines series of experiments enabling us to (i) identify an aptitude of polysulfidic, monosulfidic, and carbon- carbon crosslinks to ultrasonic devulcanization; (ii) to establish optimal conditions for the devulcanization process; (iii) to evaluate the rheological properties of devulcanized rubbers; and (iv) to measure the mechanical performance of revulcanized rubber products made of devulcanized rubber. The recycling of vulcanized elastomers (primarily used tires) has become a major environmental and social issue. The development of a novel technique for the reclaiming of rubber will have a significant impact on the further expansion of a recycling technology base through the optimization of the process and new discoveries.