Abrasion and Friction of Rubberlike Materials

Abstract

Abstract The relationship between abrasion resistance and the coefficient of friction was observed in the early days of development of the modern synthetic rubbers. It has gained new interest in connection with the appearance on the market of polyester-isocyanate rubbers of the Vulcollan type. The abrasion of a rubber object in contact with a solid depends on the forces interacting at the surface of the two materials. These forces are again dependent on the forces pressing the two surfaces together, on the relative surface speed of the one object with respect to the other, and on the nature of the surfaces of the materials. Forces acting on the rubber surface and tending to pull the surface layer away from the bulk of the material deform the bulk rubber and excite counteracting cohesive forces. Abrasion of the rubber depends on the following two factors: 1) Development of frictional forces at the surface. 2) Counteraction of the force caused by the rubbing by cohesive force in the polymer adjacent to the surface layer. The question may be raised if it is possible to improve abrasion resistance by increasing the cohesive forces (1) without affecting the frictional forces and (2) if so, to what degree. With the help of the modified Cabot-Lambourn abrader, a number of experiments have been carried out that give some answers to the correlation of abrasion and friction. Abrasion is measured in terms of abrasion efficiency, i.e., weight loss per unit of energy. Correlations are established between: (a) Coefficient of friction and normal load. (b) Coefficient of friction and percentage loss of weight. (c) Coefficient of friction and carbon black loading. (d) Abrasion efficiency, coefficient of friction, and carbon black loading. (e) Abrasion efficiency and energy spent on abrasion. (f) Percentage of slip and torque obtained.