The tribological properties of poly(p‐phenylene benzobisoxazole) pulp reinforced friction materials

Abstract

Automotive friction materials reinforced by home-made poly (p-phenylene benzobisoxazole) (PBO) pulp (fibrillated organic fibers) were prepared through compression molding. The friction and wear behaviors of the obtained composite materials were evaluated using a constant rotating speed type friction tester. The PBO pulp content and the testing loads showed clear influence on the tribological properties of the composites. Friction stability, wear rate, and morphology of sliding surfaces were carefully examined to investigate the effect of the pulp ingredient in the friction materials. Scanning electron microscopy was employed to study the morphology of the surface and wear particles. The significant wear reduction was achieved when the mass fraction of PBO pulp was 3%. Wear rates of the composites with 3% PBO pulp were measured over a load range from 0.3 to 1 MPa at different temperatures. The results pointed to two facts: (1) the wear rate of the friction material increased linearly with load at low temperature (below 200 C); (2) wear status varied with the testing loads at high temperature (above 250 C).

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