Rubber friction in aqueous solutions containing ions

Abstract

Lubricantsordinarily operate by keeping two sliding surfaces separated. The efficiency of a lubricant may be expressed by equations of hydrodynamics where the mechanical properties of the films of lubricants are adequately defined by the properties of bulk lubricant.In the case of water lubrication of black rubber at slow speeds and low pressures the lubricating ability of water is shown to be enhanced by addition of electrolytes to the water. It is thought that negative ions from the electrolytic solution collect on each sliding surface, repel each other and prevent the close approach of two sliding surfaces. Thus a thicker water film exists between the sliding surfaces than if the ion layers did not exist. The thicker film results in a reduced viscous drag force, lower than can be accounted for by conventional hydrodynamics.

From Wipers to the JKR Equation: Boundary Lubrication and Adhesion of Rubber

“…Experiments have been carried out with aqueous inorganic solutions in the absence of surfactant [1,[27][28][29][30]. The magnitude of friction measured [29,30] for a rubber-glass contact depended upon the pH (acidity/alkalinity) of the solutions.…”

Friction of rubber on ice in the presence of salt

“…Investigations have shown that rubber lubricated with salty water has a lower friction than with distilled water (Roberts and Tabor 1971, Mortimer and Ludema 1974, Davis et a1 1979. To our knowledge there are no parallel studies published on the effect of salt on rubber-ice friction.…”