Aging Characteristics of Black Filled Vs Silica Filled Compound

Low rolling resistance tires have treads composed predominantly of silica.  As such PPD adsorbs on the filler and is less available as an antiozonant and antioxidant.  This is a severe issue resulting in Low RR tires aging poorly as compared to conventional tires.

 Initial study on “partitioning” experiments showed that in a typical formulation, the amount of PPD adsorbed on the silica is quite high and a large portion of the PPD originally put into the compound will not be readily available for protection.  For untreated silica nearly 100% of the typical levels of PPD is adsorbed on the filler, in silane treated silica the percentage was somewhat lower but still a very high percentage. The partitioning experiment suggests that PPD loading in this application significantly higher than typical usages in carbon black filled compounds in order to match aging performance.   

This paper presented data comparing the aging characteristic of Carbon Black filled vs. Silica filled compounds in the laboratory.