Bulk viscoelastic contribution to the wet-sliding friction of rubber compounds

The wet-sliding friction characteristics of rubber compounds made of high cis-polybutadiene were examined with a British pendulum skid tester at room temperature. Three series of compounds were prepared-unfilled or filled with carbon black at two different levels. The bulk viscoelastic properties as characterized by the bulk glass-transition temperature for the compounds were systematically adjusted by changing the crosslinking density via sulfur vulcanization. In fact, the dynamic mechanical glass-transition temperature for the compounds ranges between approximately -100 and 20 degreesC. Consequently, the wet-sliding friction of these rubber compounds is dramatically affected. With increasing compound glass-transition temperature, the wet-sliding friction increases to a maximum and then decreases. However, the rate of increase or decrease varies with the amount of filler in the compounds. (C) 2003 Wiley Periodicals, Inc.