Impulse breakdown characteristics of polytetrafluoroethylene films have been studied using original sheet-films (U-film), films rolled at elevated temperature (R-film), and films elongated uniaxially (E-film). The R-film shows the highest breakdown strength which is independent of temperature and decreases with increase in the sample thickness. The suggests that the breakdown is due to electron avalanche process. Conductivity of the R-film is lower than that of the U-film. Observation by SEM shows that hot-rolling extinguishes voids where electrons can be accelerated easily. This extinction of voids and decrease in conductivity are thought to bring the highest breakdown strength to the R-film.
|出版ステータス||Published - 1986 12 1|
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