The Coefficient of Friction of a Polyamide/Polymethyl Methacrylate Blend System

Abstract

The coefficient of friction is an important tribological property of polymer materials. In this work, values for the coefficient of friction of a polyamide (nylon 6,6)/polymethyl methacrylate (PMMA) blend system have been measured under various compressive stresses. The results show that the coeffi cient of friction of the amorphous polymer, PMMA, increases with increasing compressive stress; while the coefficient of friction of the crystalline polymer, nylon 6,6, either stays constant or decreases with increasing compressive stress. For crystalline polymers, the coefficient of friction measured parallel to the flow direction is lower than that measured perpendicular to the flow direc tion. The effect of sample orientation on the coefficient of friction of the amor phous polymer, PMMA, is insignificant. Values for the coefficient of friction of the blends measured are lower than those calculated from the additive rule for the coefficient of friction of the blend system. It is noteworthy that values for the coefficient of friction of several specific blend compositions are lower than those of the two thermoplastics. These results are in good agreement with the predictions from the tribological controlling equations developed. Based on these findings, nylon 6,6/PMMA blends with low values of the coefficient of fric tion have been successfully developed.