Effect of Carbon Black on Heat Build-up and Energy Dissipation in Rubber Materials

The heat build-up and energy dissipation of carbon black reinforced natural rubber compounds are studied using a rebound resilience tester, Goodrich flexometer and a Coesfeld heat build-up analyser. Natural rubber compounds containing eight different carbon blacks at 50 parts per hundred (phr) were studied. The carbon blacks varied widely in their structure and surface area properties allowing quantitative correlations to the heat build-up and rebound resilience measurements to be extracted from their colloidal properties. The results show the nature of deformation dictates different levels of influence of the carbon black properties. Carbon black surface area dominates in influencing the heat build-up and energy dissipation in the Goodrich flexometer, Coesfeld heat build-up analyser and rebound resilience measurements. The Goodrich flexometer heat build-up measurement, however, is the only experimental measurement where carbon black structure places a significant role in determining the heat build-up. The differences in the levels of influence of carbon black colloidal properties can be understood when the deformation index concept is applied to the experimental results. Goodrich flexometer measurements are predominantly strain-controlled measurements while rebound resilience and Coesfeld heat build-up are a complex combination of strain and energy-controlled deformations. Understanding the type of deformation that dominates in various heat build-up and energy dissipation tests and how carbon black properties affect the results of the tests are of practical importance. It enables the heat build-up and energy dissipation tests that closely represent the type of deformation that will be predominant in field applications to be selected during compound development and characterization. It also gives an understanding of how carbon black properties can be leveraged to optimize desired heat build-up and energy dissipation properties depending on the type of deformation during compound development.