Effect of carbon black type on viscous heating, heat build-up, and relaxation behaviour of SBR compounds

Generation of heat via viscous dissipation of uncured filled rubber compounds can lead to significant temperature increment, which its estimation is very important. In this work, viscous heating and stress relaxation of uncured carbon black and silica filled SBR compounds and heat build-up of the cured one were investigated by rubber process analyzer (RPA2000) instrument. These compounds were prepared in Haake internal mixer at 60 degrees C, 10 min mixing time and a rotor speed of 40 rpm. The mixing was followed by using a two-roll mill with adding curing agents. A part of these compounds was used to prepare the cured samples for Goodrich flexometer, to determine the heat build-up of cured compounds. There was a similar trend in the data of both measurings. The results of this study showed that with increasing the particle size, i.e., decreasing the structure of carbon black,the amount of generated heat has been reduced. Fillers which cause higher viscous heating in the uncured compounds also impart higher heat build-up in the cured compounds. Results also demonstrated that compounds which contain larger particle size, i.e., lower structure carbon black have shorter relaxation time. An silica filled SBR, viscous heating, heat build-up, and stress relaxation have been increased, also.