Friction of Polymer Solutions

Abstract

Friction measurements on steel, glass, and copper with a stainless steel rider on solutions of poly(n-alkyl methacrylate)s show that as the length of alkyl group is increased the coefficient of friction is reduced. The friction values are almost the same as those obtained with n-alkyl acetates having the same alkyl length. Changes in concentration from 0.01 to 10 mg/ml yield at most an insignificant increase in friction. The progressive friction reduction with increasing alkyl length is explained in terms of increasing lateral interactions of the adsorbed polymer film with increasing fraction of alkyl lengths having one free end. These lateral interactions lead to progressively increasing rigidity which contributes to friction reduction. Measurements with copolymers of n-hexadecyl methacrylate and methacrylic acid show minimum friction with approximately 50% of methacrylic acid indicating that strongly polar groups which can interact with the surface and long alkyl groups both contribute to friction reduction. When either is decreased in concentration in the film near the surface, friction increases.

Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis, Minnesota, October 18–20, 1966.

Notes

Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Minneapolis, Minnesota, October 18–20, 1966.