Evaluation of Aged Tires with lnnerliners Containing Varying Halobutyl Rubber Levels
Event:182nd Technical Meeting Location: Cincinnati, OH Date: October 09, 2012 Author: Edward R Terrill*, Walter H. Waddell Paper Number: 26
Tires made with 100-phr of bromobutyl rubber and with blends of 8OI2O and 6OI40 bromobutyllnatural rubber in the innerliner were evaluated to order to understand the effect that the halobutyl rubber content used in the innerliner compound had on tire aging. Each of the tires was oven aged for 28 days at 70 0C and subsequently run on a 1.7-m laboratory roadwheel. Optical micrographs showed the strong effect that halobutyl content had on tire aging, namely the crack length decreased with increasing halobutyl rubber content. Modulus profiling showed the details of the aging in each tire type. The indentation modulus analysis was performed at various locations: under groove, under lug, centerline (crown), and belt edge. In all locations, the advantages of the innerliner were quantified. In all locations, use of increased halobutyl rubber levels provided an advantage in aging (oxidation) resistance. The extent of the advantage varied with location. Diffusion Limited Oxidation (DLO) modeling substantiated the aging resistance benefits of using increased halobutyl rubber in the tire innerliner and agreed with the results of the modulus profile measurements. The DLO model predicted that the effect of the tire innerliner polymer composition on the oxidation rate of the internal components would be greater during roadwheel testing than during static oven aging.