Abrasive Wear of Rubbers Based on Natural Rubber, Carbon Black, and Polyoxadiazole Fiber

Abstract

The influence of the abrasive particle size and modifiers (low molecular weight liquid rubbers (LMWRs), sulfidosilane) on the rate of wear on abrasive paper of rubbers based on natural rubber (NR), carbon black (CB), and polyoxadiazole (POD) fiber is studied as a function of structure and mechanical properties of rubbers. Model rubber blends were prepared in a closed-type mixer, the abrasive wear tests were conducted on a drum-type machine, the structure and the mechanical properties of rubbers were characterized by DMA, static tensile tests, hardness measurements, and tear resistance. The wear surfaces were analyzed by SEM. Tests have shown that the addition of fiber does not affect the rate of abrasive wear of the original NR/CB rubber regardless of the grain size of the abrasive. Addition of modifiers that increase tensile modulus M10, hardness H_Sh, tear resistance T_R, tensile strength A, and degree of crosslinking γ reduces the wear rate under friction on coarse abrasive, which is characteristic of abrasive wear with a predominance of micro-cutting. The greatest influence, judging by the value of the correlation coefficient, is exerted by the value of M10, dependent on the bond strength between the matrix and the fiber, which allows predicting the wear rate of rubbers based on the results of mechanical tests. When worn on a fine abrasive paper, the increase in M10, H_Sh, T_R, and γ on the contrary, raises the wear rate of rubber, and the tensile toughness has practically no effect on it. This is attributed to the predominance of the fatigue wear mechanism, in which the wear rate increases with contact stresses, in proportion to the strength properties, with tear resistance exerting the greater effect on the wear rate.