Thermal effects in polytetrafluoroethylene at high hydrostatic pressures

Abstract

SynopsisThe temperature changes as a result of rapid hydrostatic pressure applications are reported for polytetrafluroethylene (PTFE, Teflon) in the reference temperature range from 294" to 381°K and in the pressure range from 13.8 to 200 MN/m2. The thermal effects were found to be higher a t the reference temperature approximating the transition temperatures of 19" and 30°C than at higher reference temperature. The data were analyzed by determining the predicted thermoelastic coeEcients derived from the Thomson equation (aTlaP = uT/pC,). A curvefitting analysis showed that the empirical curve, (dT/dP) = ab(APP ~ described the experimental thermoelastic coefficients obtained from the experiments. The fact that no agreement was found between the predicted and the experimental coefficients is due to the physical changes in PTFE at the transition temperatures. The relationship between the thermal effects and the chain molecular motion is discussed by including dynamic mechanical analysis and differential scanning calorimetry DSC measurements for the PTFE samples.

Thermal and thermoelastic properties of fast extrusion furnace (FEF) carbon black loaded SBR vulcanizates

“…(3) where the proportionality constant CI was found to be a function of the carbon content in the rubber used. The fitting parameters ATm, and the values of the coefficient 7 for 100 FEF/SBR samples are given in Table 2. As the strain amplitude increases, the concentration of ruptured bonds together with free radicals increases, leading to intensified friction between particles and consequently to the observed rise in thermoelastic temperature change, as shown in Fig.…”

Effect of swelling process on thermoelastic temperature change of butadiene acrylonitrile rubber filled with polyvinyl chloride

“…The rapid deformation is closely related to an adiabatic process whereby the heat absorbed or generated during the deformation changes the temperature of the material. 6 For more explicit examination of thermoelastic phenomena, it is necessary to develop relations between force f, length l, and temperature T on the one hand, and the thermodynamic quantities, entropy S and internal energy E, on the other. 7,8 These relations could be summarized in the following equations:…”

Effect of swelling process on the thermoelastic temperature change of ethylene propylene diene rubber filled with carbon black

“…The method used involves deformation of the thermoelastic coefficient, change in entropy, enthalpy per unit length, and Gruneisen constant. It is well recognized 4 that the rapid deformation of a solid usually results in a change of its temperature. This rapid deformation is closely related to an adiabatic process, where the heat absorbed or generated during the deformation changes the temperature of the material.…”

“…One of the most recent uses of the material is for improved aging rocket 1 insulator compounds, filled with cork, asbestos fiber, and iron oxide. The basic structure of EPDM is represented by the following schematic configuration Test samples (EH 4 , EH 6 , EH 8 , and EH 10 ) were obtained by introducing different concentrations of carbon black HAF (high-abrasion furnace black) in ethylene propylene diene polymer.…”