Papers by Keyword: Poly(tetrafluoroethylene)(PTFE)

Abstract: The effect of dc discharge treatment at the anode and cathode on the surface properties of polytetrafluoroethylene (PTFE), tetrafluoroethylene–hexafluoropropylene copolymer (FEP) and poly(vinylidene fluoride) (PVDF) polymer films was studied. It was found that the modification of the films under conditions that ensure the separation of the discharge active species acting on the polymer materials makes it possible to achieve substantially lover values for the contact angle and higher values for the surface energy than in the case of other modes of discharge. The changes in the composition and structure of the films were studied by means of IR spectroscopy and electron spectroscopy for chemical analysis (ESCA). It was found that new oxygen-containing groups are formed on the polymer surface as a result of dc discharge treatment. To appreciate the adhesion characteristics of fluoropolymer films modified by dc discharge, American Society for Testing and Materials Standard Test Method for Measuring Adhesion by Tape Test (ASTM D3359-02) was used. The adhesion tape Scotch 810 and vacuum metallization of the film surface are account for the basis of this method. It was found that the adhesive bonding strength of the plasma treated films substantially increased.

Abstract: Poly(tetrafluoroethylene)(PTFE) thin films were coated onto metal substrates by a spin coat apparatus, vacuum evaporator and RF sputtering, and their adhesion and friction properties evaluated. PTFE thin film coated onto nickel-titanium (Ni-Ti) substrate by spin coating showed a low friction coefficient, however pull strength between the thin film and Ni-Ti substrate was low. In order to increase the pull strength, PTFE and poly(vinyl alcohol) (PVA) composite thin films were introduced between the PTFE thin film and Ni-Ti substrate by spin coating. PTFE thin film was also coated onto SUS302 substrate by a vacuum evaporator. This PTFE thin film showed poor adhesion to the SUS302 substrate. The adhesion was enhanced by heating of the substrate during the evaporation. In addition, a PTFE and ethylene vinyl alcohol (EVOH) composite thin film showed higher adhesion strength than that of the PTFE thin film. Poly(fluorocarbon) thin films were prepared by a conventional RF sputtering with PTFE target. These thin films showed a higher friction coefficient than that of the pristine PTFE. Molecular structures of the poly(fluorocarbon) thin films prepared by RF sputtering were different from the pristine PTFE. This difference may have influenced the friction coefficient. The pull strength of metal thin films such as gold, copper, nickel and aluminum deposited on the sputtered PTFE thin films by vacuum evaporation was measured. The nickel thin film adhered to the PTFE thin film most strongly of all the thin films.