Accession Number : ADA303579

Title :   Friction Transition In Polyimide Films as Related to Molecular Relaxations and Structure.

Descriptive Note : Technical note,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : Fusaro, Robert L.

PDF Url : ADA303579

Report Date : APR 1975

Pagination or Media Count : 31

Abstract : The friction characteristics of polyimide films bonded to metallic substrates were studied from 25 C to 500 C. These results were correlated to molecular structure and the results of torsional braid analysis (TBA). A large friction transition (0. 23 to 0.03) was found to occur at 45 C + OR - 5 C. It was postulated that this transition was initiated by some molecular relaxation, which gave the molecules a degree of freedom by which an external mechanical stress could rearrange the molecules into a structure, such as an extended chain, which is conducive to easy shear. Above 300 C the friction characteristics were found to be dependent on the thermal prehistory of the film. (MM)

Descriptors :   *SOLID LUBRICANTS, *SLIDING FRICTION, *POLYIMIDE PLASTICS, THERMOMECHANICS, METALS, HIGH TEMPERATURE, THERMAL STABILITY, SUBSTRATES, GLASS, DEGREES OF FREEDOM, TRANSITION TEMPERATURE, POLYMERIC FILMS, MOLECULAR STRUCTURE, RELAXATION, TRANSITIONS, BRAIDS, MOLECULAR PROPERTIES, TORSION, POLYIMIDE RESINS.

Subject Categories : Lubricants and Hydraulic Fluids
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE