Influence of Frictional Vibration on Wear When Razor Rubs Polypropylene Single Fiber

The phenomenon, when a polypropylene single fiber was rubbed by a razor, was investigated, and morphology of the rubbed fiber was observed. In particular, presence or absence of occurrence of friction vibration on the razor during rubbing was paid attention. In this study, an original friction and wear testing machine, which can change the free-end length of the razor, the testing tension and the testing speed, was used. As a result, when the free-end length of the razor 0.1 mm, friction vibration was not generated on the razor and a part of fiber surface was scraped off equally. However when the free-end length of the razor 1.0 mm, friction vibration was generated on the razor and bumps were formed periodically on the fiber surface. It is because of increase of spring constant of the razor by increase of the free-end length of that. Moreover,press-fitted depth of the razor deepened and also the period of bumps (the structure period) increased, as the testing load increased. On the other hand, the structure period decreased, as the testing speed increased. This tendency was reverse to a tendency which was derived from a model of the friction vibration. However negative speed dependence of friction coefficient, which was reported by many researchers, can explain the former tendency. In conclusion, when spring constant of the razor is low, friction vibration occurs on the razor. Furthermore, friction vibration on the razor changes morphology of damage on the fiber significantly, and forms periodic bumps on the fiber.