Liquid isoprene rubber as a safe processing aid in natural rubber compounds

Authors Details :
Chandresh M. P.,
Roopa S.,
Siddaramaiah

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In order to overcome the carcinogenic ‘polycyclic aromatic hydrocarbon’ emission from aromatic oils, which are restricted in European countries since 2010, various efforts have been made to replace the aromatic oil in rubber-based compounds either fully or partially. The authors in the present work have used liquid isoprene rubber (LIR50 or LIR) as a reactive plasticizer in natural rubber (NR) compound at different loadings (2, 4, 6 and 8 phr) and have studied its effect on viscosity, curing characteristics and physico-mechanical properties. These results were compared with the control compound containing conventional aromatic oil as plasticizer. From the experimental data, it was noticed that, the minimum torque for control compound was 0.33 dNm and that for LIR based compounds ranged between 0.16 to 0.56 dNm. The LIR based compounds exhibited slightly higher Mooney viscosity but offers the same scorch safety. The study supports the utility of LIR as a promising alternative, as revealed by the comparable rheological and physico-mechanical properties attained with the usage of appropriate quantity of LIR, unlike the other alternatives of the previous investigations that usually showed a property difference. Keywords: aromatic oil, liquid rubber, reactive plasticizer, safe processing oil.