Interaction of Hydrocarbon and Surface-active Agent

Abstract

IT is generally assumed, in colloidal systems, that the hydrocarbon carrier plays a negligible part in determining the effectiveness of surface-active agents. We have carried out scuffing experiments using a 4-ball machine which show this is not always true. The machine consisted of three 1-in. hard steel balls clamped together in a cup and flooded with lubricant, with a 4th ball loaded against the other three, such that the centres of the four are at the corners of a tetrahedron. The 4th (top) ball is rotated at speeds up to 200 r.p.m. The solvents were straight-chain paraffins and the surface-active agents long-chain acids, amines, and alcohols, in 0.3 per cent molar concentrations. The number of carbon atoms in the agents were varied and the loads on the top ball increased in 15-lb. increments (at about 5-min intervals) until scuffing started. This point was marked by definite stick slip oscillations, and an increase in friction.