Frictional Coefficient and Boundary Lubrication of Synthetic Fibers(I) -Effects of Chain Length of Lubricant-

합성섬유의 마찰계수와 경계윤활(I) -유제의 탄소원자수의 영향-

The efficiency of the lubricating action of oil, from the point of view of the molecular mechanical nature of friction, is caused, on the one hand, by a reduction in the forces of adhesion interaction and in the mechanical strength of the bridges in the bond. On the other hand, it is associated with a reduction in resistance to elastic or plastic repulsion to disintegration of the thin surface layer and to its maximum localization, i.e. with an increase in the gradient of its mechanical properties. It depends on the nature of lubricant, on the structure of its molecules, on its chemical composition, on temperature, and a series of other mutually related parameters. Moreover, lubricating action is conditioned not only by the properties of a lubricant introduced from an external source, but also by its interaction with the surface of a solid body and by mutual interaction between hard surfaces. In order to investigate the frictional behaviors of boundary lubrication of the synthetic fiber, various chain length of straight chain fatty acids and fatty alcohols were empolyed as lubricants. The frictional coefficient of polyester fibers were measured by Rothschild Friction meter at the velocity range from 0.5 to 100m/min. The effects of chain length of lubricant, speed and temperature are presented. The conclusions obtained from this study are as follows. 1. At any given hydrocarbon chain length, fatty acids are more effective on the frictional coefficient than fatty alcohols. 2. For each homologous series, the frictional coefficient decreases with increasing lubricant chain length up to approximately fourteen carbon atoms, after which the frictional coefficient remains essentially constant. 3. The frictional coefficient always increases with the increase of sliding speeds. 4. The frictional coefficient initially decreases with increasing temperature of friction pin and shows the minimum values at the near melting point of lubricant, and then sharply increases their values as the temperature increases over the melting point.