REDUCTION OF POLYMERIC FRICTION BY MINOR CONCENTRATIONS OF PARTIALLY FLUORINATED COMPOUNDS
NAVAL RESEARCH LAB WASHINGTON DC
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A new approach to the reduction of boundary friction in solid polymers was studied. Dry frictional properties of several classes of polymeric solids were reduced significantly by the addition of small proportions of a suitably designed surface-active compound. Appropriate fluorocarbon derivatives were prepared and found effective in polymethyl methacrylate, polyvinyl chloride, and in several polyvinylidene chloride copolymers. These addition agents are effective both in polymer films prepared by evaporation from a solvent and in thick disks prepared from the melt. The low-energy surfaces formed by the fluorinated additives may also be selfhealing, that is, any surface-active molecule lost from the film may be replaced by the diffusion of additional material to the interface. The decrease in friction caused by the addition agent is accompanied by an increase in the equilibrium contact angle of each of several liquids on the polymer surface. The small proportion of addition agent used causes only a small decrease in the hardness of the polymers.
- Lubricants and Hydraulic Fluids