Mechanisms of Rubber Abrasion in Unsteady State

Abstract

Abstract Abrasion of rubber under the action of mechanical stress appears to involve two basic processes: micromolecular fracture and macrodelamination. The formation of ridges mainly results from the effect of tearing and tensile rupture, but the production of small particles is mainly due to the effect of microcutting. Ridge and small particle formation are basic characteristics of rubber abrasion. The physical processes during dry wear are gradual tearing leading to crack growth and also rupture of the tongue tip. A new concept of rupture length per revolution has been introduced, which is itself a function of the number of revolutions that have occurred during the unsteady state. Based on this, a quasi-theoretical relation for the rate of wear has been proposed. It reflects the influence of several factors on the rate of wear in a comprehensive way, and, it was verified by the experimental results. In the unsteady state of abrasion, the rate of wear and the spacing of the abrasion pattern not only depend upon the frictional force but also upon the number of revolutions. The relationship between the spacing and the frictional force is exponential. The influence of the rotational speed on the wear rate could be neglected when the speed did not exceed 18 rev/min. Oily wear was found at relatively small frictional forces (kN/F=0.24−0.41 m). The action of microcutting and the decomposition of the rubber are both prerequisites and sufficient conditions for oily wear to be produced. The same rubber shows two different modes of wear under different frictional forces. But a quantitative condition for the change from dry wear to oily wear is not yet clear.