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(tetrafluoroethylene) (PTFE with average size of about 500 nm, 7A–J) were purchased from Dupont (USA); and the inorganic nanoparticle of CaCO 3 with average size of about 100 nm is of industrial grade, which is bought directly from Omya (China). The nanoparticle size of SiO
Abstract
Results of high thermal resolution microcalorimetric and dilatometric measurements performed on reducer — polytetrafluoroethylene (M-PTFE) pyrotechnic compositions have been discussed. The materials were selected for the study because of their behaviour in combustion tests. Two complementary thermal properties, i.e. the specific heat and coefficient of linear thermal expansion (CLTE), have been analysed in detail. The specific heat was obtained from DSC measurements performed from −20 to 375C. Measurements of CLTE and linear expansion were carried out from −40 to 270C. In both cases the measurements were performed on thermocycling with the high thermal resolution preserved. A special attention has been paid to a two-stage phase transition occurring just below the room temperature.
Abstract
Simultaneous TG/DTA has been used to study the thermal decomposition of binary compositions containing polytetrafluoroethene (PTFE) with silicon (Si), calcium silicide (CaSi2), ferrosilicon (FeSi) or iron (Fe) powders. In nitrogen and under dynamic heating program the thermal decomposition of Si/PTFE and CaSi2/PTFE is an exothermic process. The other two compositions decompose endothermically. In each case the decomposition reactions show first-order kinetics but only iron does not change considerably the kinetics of PTFE depolymerization. The constants of the decomposition rate at 850 K for silicon containing reducers are about four times higher than those of PTFE and Fe/PTFE.
plasma-treated PTFE . Surface and Interface Analysis , 16 , 412 – 417 . DOI: 10.1002/sia.740160186. [3] Tan K. L. , Woon L. L. , Wong H. K
Abstract
The influence of the size of poly(tetrafluoroethylene) (PTFE) particles, obtained from the formed polymer (bar) by cutting on the fusion was studied in order to get information on the polymer breaking consequence.Three fractions of particle diameters between 1.62–0.42 mm were submitted to DSC in nitrogen, DTA in air and DRX analyses and the results compared to those obtained with the non-processed formed polymer and PTFE mentioned in literature.The study on the heating rate influence on the melting temperature range (
T) and the specific heat of fusion (Q/J g–1) carried out with the fraction of 0.82 mm diameter afforded a method for estimating the polymer specific caloric capacity by means of DSC data.
Summary
Direct analysis of airborne particulate matter collected on PTFE-membrane filters was performed using synchrotron radiation X-ray fluorescence (SRXRF). Standard filter samples prepared in the laboratory were utilized to evaluate the setup performance as well as the capability of the proposed method. The influence of experimental parameters including the beam size and sample-to-detector distance were thoroughly examined. A total of 10 elements on the filter can be determined. It was found that the optimum detection efficiency for the system can be achieved if using a 3 mm´3 mm beam size as well as a 7 cm sample-to-detector distance with a two-step measurement procedure with photon energy less than 7 keV and 14 keV, respectively.
Abstract
Proton beams of diameters of 3 mm and 3 μm, were used to observe the differences in PIXE yield from pure metal targets encapsulated with PTFE, glass (macor) and nylon. The beam energy was kept constant at 700 keV. Beam currents varied from about 200 pA with the microbeam and between 1–10 nA with the macrobeam. Considerable enhancement was observed mainly with the use of PTFE, up to about a factor of 18 with the macrobeam and 306 with the microbeam.
process, which offers porosity of 65% and average pore size of 215 μm [ 13 ]. Recently, combustion synthesis conditions in the Ni + Zr + polytetrafluoroethylene (PTFE) mixture were studied to obtain porous (≈65%) NiZr-based materials with 50–600 μm
Introduction Fluoropolymers are technical polymers with very special properties and applications. The most important fluoropolymer is poly(tetrafluoroethene) (PTFE or Teflon) consist of a fluorinated straight chain polymer
