Ground tire rubber (GTR) reclamation: virgin rubber/reclaimed GTR (re)vulcanizates

Thermochemically partially devulcanized ground tire rubber (GTR(D)) was revulcanized in compositions with different virgin rubbers. Two different devulcanizing groups (mixture of softeners) with and without processing oil have been used for GTR treatment. As virgin rubbers methylstyrene/butadiene (SBR), isoprene (IR) and butadiene (BR) rubbers or their combinations were selected. They were cured by using sulfur, tetramethyl thiuram disulfide (TMTD) or peroxide based vulcanizing systems. The Rubber/GTR(D) (re)vulcanizates with the GTR(D) content from 20 to 80 wt.% have been prepared and studied. Vulcanization by sulfur system was found as preferable for IR/GTR(D) formulations. The best properties for BR/GTR(D) and SBR/GTR(D) vulcanizates were reached with the vulcanization system based on TMTD. The co-curing in the interphase between the GTR(D) particles and the surrounding rubber matrix improves the mechanical properties of (re)vulcanizates obtained. The reclaimed GTR(D) studied has been used successfully in standard formulations for tires instead of the part of virgin rubbers.