Mechanochemical surface activation of ground tire rubber by solid-state devulcanization and grafting

Cured rubber powder was successfully devulcanized under the application of high-energy ball milling. An attempt was made to improve the efficiency of devulcanization with a phenolic antioxidant (2,6-di-tert-butyl-4-methyl-phenol). In addition, the grafting of virgin natural rubber to the surface of rubber powder was promoted by milling under an inert atmosphere. The extent of mechanochemical devulcanization was studied by estimation of the sol-gel fractions and crosslink densities. Our findings suggest that the process led to a preferential breakage of sulfur crosslinks. The curing behavior of the compounds and the mechanical properties of the vulcanizates containing treated rubber powder and fresh rubber were investigated. The chemical and mechanical properties depended strongly on the experimental milling conditions, which could consequently be controlled to improve the quality of the reclaimed rubber. (C) 2003 Wiley Periodicals, Inc.