A Quantitative Study of the Carbon Black Reinforcement System for Tire Tread Compounds

Abstract

Abstract This comprehensive program clearly shows the influence of the four defined reinforcement system variables. The tread wear testing conducted over an extremely wide severity range illustrates how the influence of each variable or factor changes as the tire use of test severity is changed. The quantitative influence of the four variables is best illustrated by the index severity gradient, while the index range serves as a quick indicator. The influence of each factor of the reinforcement system increases as general test severity is increased. Carbon blacks with high structure and surface area are substantially superior to blacks with normal structure and surface area at the higher test severities. At the higher general severities, increased oil content produces higher wear rates. At any given severity level, the rate of wear passes through a minimum as carbon black level is increased. The carbon black content at this minimum wear rate shifts to higher values as general severity is raised. Test results at a series of specific cornering force levels (0.10–0.30 g range) indicate that the relative wear of typical tread compounds demonstrates crossovers of index values. Compounds that show superior wear resistance compared to a reference compound at high cornering severities often show inferior wear resistance at low cornering severities. Therefore, for maximum tread life or wear resistance, the reinforcement system with any tread rubber or rubber blend must be carefully adjusted to the anticipated level of tire use severity. The introduction of improved-technology carbon blacks with increased rubber-black interaction that is promoted by high DBP and EMA levels is a substantial advancement in rubber materials science and is most important for the production of high-performance long-treadlife tires.