The molecular conformations of polytetrafluoroethylene: forms II and IV

Macroscopic Evidence of Thermally Activated Friction with Polytetrafluoroethylene

“…For the case of 2% RH, the friction coefficient climbs as the temperature is reduced to 225 K, which corresponded to visible ice formation on the counterface (initially shiny but becoming hazy); deviations from this trend were observed during the room temperature phase transitions [17][18][19] and during a hypothesized glass transition near 400 K [17,[20][21][22]. At 2% RH with a background temperature of 296 K, the frost-point is approximately 243 K. As the temperature was further reduced below 225 K, the friction coefficient continues to fall, which is presumably due to a more contiguous film of ice on the surface.…”

Ultra-broadband THz time-domain spectroscopy of common polymers using THz air photonics

“…Despite of the apparent simplicity of the CF 2 chain which may seem similar to that of PE, the presence of polar bonds along the backbone chain and its helical structure make the physical properties of this material very different from those of PE. The spectral assignment and the crystalline structure of PTFE (existing in at least three different phases in the temperature range 273-313 K at ambient pressure) has been discussed extensively [28][29][30]36].…”

Nanotribological characterization of perfluoroalkylphosphonate self-assembled monolayers deposited on aluminum-coated silicon substrates

“…This fact implies that the perfluorinated chain film structure is more rigid than that of the hydrocarbon chain film. The C-C bonds of alkylcarbon chains can freely rotate around (Clark 1999). Bhushan and Liu (2001) and Liu and Bhushan (2002) have used a molecular spring or brush model to explain why less compliant SAMs show larger friction.…”