Study of relaxation behavior and processability of polybutadiene rubber composition

In this work, nickel-catalyzed high-cis 1,4-polybutadiene rubbers (PBR) with different molecular weight, molecular weight distribution, and Mooney relaxation time have been solution blended at different ratios and their rheological, thermal, and physical properties were characterized. PBR blend compositions showed similar processability as pristine rubber grades at higher temperature, but their Mooney relaxation time and rheological branching index (BI) are distinctly different from both pristine PBR grades at low temperature. In addition, Mooney relaxation time and BI of the blends were found to be independent of blend compositions; however, glass transition temperature (Tg), cis%, volatile% of the compositions remain similar to the raw rubbers.