Accession Number : AD0696964

Title :   STERIC FACTORS AFFECTING FRICTION AND WEAR OF POLYALKENES.

Descriptive Note : Final rept.,

Corporate Author : NAVAL SHIP RESEARCH AND DEVELOPMENT LAB ANNAPOLIS MD

Personal Author(s) : Lagally,Paul ; Nagy,Robert

Report Date : OCT 1969

Pagination or Media Count : 35

Abstract : The sliding performance of polyalkenes in rubbing contact with a metal (oxide) surface was investigated in relationship to the structural order and molecular symmetry. High-density polyethylene surpassed, in its overall sliding performance, the substituted crystalline polyalkenes. The ability of the conventional (branched) polyethylene to function as a low friction contact when water is the lubricant is attributed to the presence of amorphous regions also present in the linear type. The erratic sliding of isotactic polybutene (and other homologs) is explained by internal friction in the rubbing interface resulting from polymorphic transitions. Cross-linking with a peroxide increases friction of polyethylene, but it reduces the abrasive wear of the composites containing carbon black. The use of highly reactive channel blacks requires no free radical source, and a further reduction in abrasive wear can be achieved by auxiliary cross-linking agents such as ethylene imine which reacts exothermally with the acidic surface of the carbon black present in the composite structure. The ratio of crystalline and amorphous conformations governs the overall sliding performance of polyalkenes. Frictional effects due to different mating surfaces are explained by material transfer and interfacial phase elastic phenomena. (Author)

Descriptors :   (*POLYETHYLENE PLASTICS, FRICTION), (*COMPOSITE MATERIALS, FRICTION), (*WEAR RESISTANCE, *POLYMERS), CARBON, CROSSLINKING(CHEMISTRY), PEROXIDES, MOLECULAR STRUCTURE, DENSITY, BEARINGS

Subject Categories : Laminates and Composite Materials
      Lubricants and Hydraulic Fluids
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE