Phase behavior at low temperature of poly(tetrafluoroethylene) by temperature-modulated calorimetry

Pucciariello, Rachele; Villani, Vincenzo

doi:10.1016/j.jfluchem.2003.07.019

Cited by 6 publications

(2 citation statements)

References 32 publications

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“…The second peak does not change with both methods. This kinetic effect has already been observed by means of ac-calorimetry on the PTFE [25] and frequency effects have already been reported at low frequencies with TMDSC [26,27]. For the presented ac-calorimetric device, we have worked out a thermal model for the sample and the sample holder which enable us to extract data in a larger frequency range (0.020Hz-40Hz) than the frequency range given by the inequalities (4).…”

Section: Ptfe : a Model For Out Of Equilibrium Phase Transitions In P...mentioning

confidence: 79%

Thermodynamics of small systems by nanocalorimetry: From physical to biological nano-objects

et al. 2009

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Membrane based nanocalorimeters have been developed for ac calorimetry experiments. It has allowed highly sensitive measurements of heat capacity from solid state physics to complex systems like polymers and proteins. In this article we review what has been developed in ac calorimetry toward the measurement of very small systems. Firstly, at low temperature ac calorimetry using silicon membrane permits the measurement of superconducting sample having geometry down to the nanometer scale. New phase transitions have been found in these nanosystems illustrated by heat capacity jumps versus the applied magnetic field. Secondly, a sensor based on ultra-thin polymer membrane will be presented. It has been devoted to thermal measurements of nanomagnetic systems at intermediate temperature (20K to 300K). Thirdly, three specific polyimide membrane based sensors have been designed for room temperature measurements. One is devoted to phase transitions detection in polymer, the second one to protein folding/unfolding studies and the third one will be used for the study of heat release in living cells. The possibility of measuring systems out of equilibrium will be emphasized.

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Section: Ptfe : a Model For Out Of Equilibrium Phase Transitions In P...mentioning

confidence: 79%

Thermodynamics of small systems by nanocalorimetry: From physical to biological nano-objects

et al. 2009

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“…The crystallinity of N-0-0, R-360-4 and F-360-4 is 78.0, 52.5 and 24.2%, respectively. PTFE is qualified as a semi-crystalline material, 10 and its molecules align in the composition of folded-ribbons forming lamellae crystal, [26][27][28] therefore, the obtained results could be interpreted from an angle of PTFE crystal. Starkweather 29 suggested that the transformation from extended chain crystal (ECC) in virgin PTFE into folded chain crystal (FCC) in molten PTFE (which is kinetically more accessible) could result in a lower melting point.…”

Section: Effect Of Sintering Mannermentioning

confidence: 82%

Sintering process investigation during polytetrafluoroethylene hollow fibre membrane fabrication by extrusion method

Jia

Kang

Zou

et al. 2017

High Performance Polymers

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In this study, the effect of sintering conditions including manner, temperature and duration on properties of polytetrafluoroethylene (PTFE) hollow fibre membrane fabricated by extrusion method was intensively investigated. Different from un-sintered and relaxed sintered, the fixed sintered PTFE hollow fibre membrane was observed to generate a uniform ‘fibril–node’ porous structure and a main crystal transformation to folded chain crystal with smaller size. Consequently, it was found that for fixed setting sintering, both temperature increase from 340°C to 400°C and duration prolongation obviously improved pore size, ethanol permeation performance and mechanical strength. Additionally, the test results revealed that the membrane sintered below virgin melting point (350°C) had a noticeable higher porosity but poorer ethanol permeation performance that could be primarily attributed to increased ratio of closed pore. The sintering condition exhibited evident influence on PTFE hollow fibre membrane thermal stability, though it showed no alteration to the thermal decomposition of PTFE. The obtained PTFE hollow fibre membrane was tested to evaluate their vacuum membrane distillation (VMD) performances. It was found that PTFE membrane from lower sintering temperature delivered a better salt rejection; on the other hand, the permeate flux was improved by increased vacuum pressure during VMD operation.

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Polytetrafluoroethylene matrix nanocomposites for tribological applications

Burris

Santos

Lewis

et al. 2013

Tribology of Polymeric Nanocomposites

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Phase behavior at low temperature of poly(tetrafluoroethylene) by temperature-modulated calorimetry

Cited by 6 publications

References 32 publications

Thermodynamics of small systems by nanocalorimetry: From physical to biological nano-objects

Thermodynamics of small systems by nanocalorimetry: From physical to biological nano-objects

Sintering process investigation during polytetrafluoroethylene hollow fibre membrane fabrication by extrusion method

Polytetrafluoroethylene matrix nanocomposites for tribological applications

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