Characterization of PTFE Using Advanced Thermal Analysis Techniques

Abstract

Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer used in numerous industrial applications. It is often referred to by its trademark name, Teflon. Thermal characterization of a PTFE material was carried out using various thermal analysis and thermophysical properties test techniques. The transformation energetics and specific heat were measured employing differential scanning calorimetry. The thermal expansion and the density changes were determined employing pushrod dilatometry. The viscoelastic properties (storage and loss modulus) were analyzed using dynamic mechanical analysis. The thermal diffusivity was measured using the laser flash technique. Combining thermal diffusivity data with specific heat and density allows calculation of the thermal conductivity of the polymer. Measurements were carried out from −125 • C up to 150 • C. Additionally, measurements of the mechanical properties were carried out down to −170 • C. The specific heat tests were conducted into the fully molten regions up to 370 • C.

Interlayer thermal conductivity of rubrene measured by ac-calorimetry

“…(The interface thermal resistance typically increases by ~ 50% between room temperature at T = 130 K. either saturated or decreasing with decreasing temperature and v c is expected to be only weakly temperature dependent, Eqtn. (6) implies that  also increases with decreasing temperature, as would be expected for phonon-phonon scattering. This is again consistent with being larger than the interlayer spacing.…”

“…6,7 While such low values of κ may limit the use of these organic semiconductors in microelectronics, they are favorable for possible thermoelectric applications. 7 Because rubrene has a layered structure, it is also important to know its interplane thermal conductivity.…”

“…One disadvantage of the 3 technique is that for a layered, anisotropic crystal the heater's oscillating temperature will be a function of the geometric mean of the "in-plane" and transverse thermal conductivities, 15 so the two components are not separately determined; in addition, it may be difficult to apply a low-noise Joule heater to some organic materials without damaging the material. Alternatively, other investigators have used chopped light to apply oscillating power to one surface of the sample and measured the oscillating temperature at different positions and/or frequencies; [6][7][8][9][10][12][13][14] the frequency dependent response is a function of the thermal diffusivity, D  /c, where c is the specific heat,  the mass density, and  the thermal conductivity. Most commonly, the oscillating temperature is measured on the opposite surface as a function of the lateral distance from the light, either by screening the light from part of the sample [8][9][10]14 or by using a laser to illuminate a small spot.…”

Advanced biomaterials in hip joint arthroplasty. A review on polymer and ceramics composites as alternative bearings

“…It does not adhere to other materials and has the lowest coefficient of friction of all solids. However, clinical studies involving PTFE acetabular cups in the total hip replacement prostheses showed unacceptably high wear and distortion [37]. The wear debris resulted in extensive tissue reaction and even formation of granuloma.…”

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“…Diffusion of CO 2 was most significant in the DOC cooling coil, a 1.5-m long portion of tubing positioned right after the combustion column, probably because this tube carries hot carrier gas and water vapor that increases PTFE diffusivity (Blumm et al 2010). Other non-PTFE components were tested for microleaks or CO 2 diffusion but were not found to be significant contributors.…”