The fillers such as carbon black and silica were incorporated in to the fresh natural rubber (NR) latex by a modified coagulation process. The coagulum containing fillers was dried in the conventional way to get latex filler masterbatches. NR/BR blend compounds were prepared by mixing the master batch with the required quantity of BR and other compounding ingredients. The compounds were vulcanized and characterized for mechanical and dynamic properties. It was observed that blends prepared from master batches had better mechanical properties like tensile strength, modulus, tear strength, abrasion resistance, hardness and lower heat build-up compared to blends prepared using dry rubber mixing technique. As the proportion of BR in the blend increased the abrasion loss reduced while the hardness and heat build-up increased for all the blends, due to the unique micro structure of cis-1, 4-polybutadiene rubber. There was reduced filler-filler interaction on blending NR with BR for the blends based on masterbatches. Filler dispersion data indicated that filler dispersion was not adversely affected on blending. From the plots of tan d versus temperature it was observed that for the pure materbatch there was a lowering of tan d peak height indicating better polymer-filler interaction, compared to the mill mixed compound. The tan d value at 60 oC and hence the rolling resistance was lower for the 80/20 NR/BR blend prepared using the masterbatch.
Carbon black, Latex masterbatch, Natural rubber latex, Polybutadiene rubber, Silica
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