Reinforcing effect of reclaim rubber on natural rubber/polybutadiene rubber blends

Mechanochemically devulcanized ground rubber tire (GRT) was revulcanized in a composition with natural rubber (NR) and polybutadiene rubber (PBR). Reclaiming of GRT was carried out by tetra methyl thiuram disulfide (TMTD) in the presence of spindle oil, a paraffin base rubber process oil. The cure characteristics and tensile properties of NR/PBR compounds were investigated. Results indicate that the minimum torque and Mooney viscosity of the NR/PBR compounds increase with increasing reclaim rubber (RR) loading whereas the scorch time remains unaltered but optimum cure time exhibits a decreasing trend due to the presence of active crosslinking sites in the reclaim rubber. The (re)vulcanization of different NR–PBR/RR blends was found to give a new low cost product with adequate properties. The mechanical properties before and after aging of NR–PBR/RR blend system and different proportions of carbon black loaded NR–PBR/RR blend system were studied. Tensile strength increases with increasing the proportion of reclaim rubber, but for all the vulcanizates the values are less than those of the control formulation. Thermogravimetric analysis of RR, NR–PBR and different NR–PBR/RR vulcanizates was carried out in order to get thermal stability of the vulcanizates. The effects of variations of RR loading on dynamic mechanical properties like loss tangent, storage and loss modulus were studied.

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► A new elastomer product is developed by blending of reclaim rubber with fresh rubber at various proportions.
► The improved mechanical properties of blend vulcanizates are due to the enhanced interfacial interaction between reclaim and fresh rubber.
► The DMA studies indicated that blend vulcanizates had lower internal friction losses of molecular chain.
► The SEM studies indicated that blend vulcanizates had better interface coherence and homogeneity between the reclaim rubber and matrix.
► Isothermal aging test reveals that the aging performance of reclaim rubber containing vulcanizates is superior to fresh rubber vulcanizates.