Oscillatory rheometry and dynamic mechanical analysis (DMA) were conducted on unvulcanized and vulcanized model tire tread compounds. Commercially available carbon black activators (also called coupling agents) were introduced to two of the three formulations during the compounding stage. Prior to vulcanization, differences in dispersion between the compounds with and without activators dominated the viscoelastic properties, as defined by reduced zero-shear complex modulus and subsequent Payne effect. After vulcanization at 160°C for 20 minutes, the performance of the two activators diverged, with the sulfurous activator increasing Payne effect. This was thought to be caused by flocculation effects during curing.

• Why there is an interest in utilizing carbon black activators in tire compounds
• Discussion of methods for measuring viscoelastic response
• The effects of commercial carbon black activators in model tire treads