Characteristics of the structure and properties of low-temperature fractions recovered from the powder ultradispersed polytetrafluoroethylene by sublimation

Thermal properties and degradation of polytetrafluoroethylene low‐molecular fractions

“…For the fraction isolated at 50°C, the bands intensities ratio I 1154 / I 1786 ~ 8, that, in accordance with the regularity found in Ref. , corresponds to the length of a chain consisting of eight CF 2 fragments. For the fraction isolated at 100°C, the bands intensities ratio I 1154 / I 1786 ~ 18, that, in accordance with the regularity , corresponds to the length of a chain consisting of 18 CF 2 fragments.…”

“…The presence of the band characterizing vibrations of CF 2 groups in the spectrum (1,154 cm −1 ) indicates to preservation of chain molecules in the gas phase (although, molecules are shorter than in the initial samples). The bands intensities ratio I 1154 /I 1780~3 -4, that, in accordance with the regularity [17], corresponds to a very short chain, it is not more than 3-4 fragments of CF 2 .…”

“…The low‐frequency range containing bending and out‐of‐plane vibrations of CF 2 groups, γ ω (CF 2 ) vibrations (640 cm −1 ), and deformation and pendulum vibrations of CF 2 groups (555 and 516 cm −1 ) is not required for further discussion; therefore, corresponding bands are not presented in the figures. The IR spectra of UPTFE and the low‐molecular fractions, notably, contain the bands at 1786 and 985 cm −1 which absent in the PTFE spectrum. Weak bands at these frequencies appeared in the IR spectra of PTFE samples, which were subjected to destruction by radiation irradiation .…”

Peculiarities of the structure of copper- and nickel-fluoropolymer composites fabricated by explosive pressing

“…The second feature manifested as a lowintensity peak at 317 8C can be also related to melting, but in this case to that of the part of the fluorocarbon material formed during partial destruction of PTFE in the process of EP treatment. PTFE short chains and defect structures are characterized by lower melting points [16]. The possible emergence of such formations was shown above by the energy-dispersive analysis data.…”

“…The released fluorine forms CF 3 groups (end or side ones). The above features are characteristic for PTFE destruction [16]. In the area of transition of these monolith areas (1&2), one observes from the SEM data the area composed of fibril structures (length 1-5 mm, thickness 40-150 nm).…”