Electrical Conductivity Enhancement of PTFE (Teflon) Induced by Homogeneous Low Voltage Electron Beam Irradiation (HLEBI)

Abstract

Electrical conductivity (·) enhancement, control, aging stability, and linear relation between · and reciprocal temperature (1/T) in PTFE (Teflon) had been examined by homogeneous low potential electron beam irradiation (HLEBI). Irradiations up to 0.432 MGy were found to raise the · of PTFE more than two orders of magnitude. In addition, control of electron movement or Fermi level by HLEBI on polymers seems possible since at low HLEBI levels up to 0.216 MGy, a strong dependence on · was observed. Aging stability investigation showed the saturated conductivities at 10 6 s (· s ) (2.5 © 10 ¹16 and 3.6 © 10 ¹15 S m ¹1 ) obtained at EB doses of 0.0432 and 0.432 MGy, respectively were approximately 4.9 and 70.6 times higher than · of untreated PTFE (5.1 © 10 ¹17 S m ¹1). Although the aging initially reduced the · of irradiated samples, · s were remarkably higher than the untreated. For example, the lower dose 0.0432 MGy samples decayed significantly, but its · s value (2.5 © 10 ¹16 S m ¹1) was still about 490% above untreated condition at 5.1 © 10 ¹17 S m ¹1. ESR (electron spin resonance) measurements showed aging for 10 6 s only slightly reduced the peak intensity of irradiated PTFE. This indicated the charge carriers generated did not easily decay. Results agree with the literature where PTFE was irradiated with VUV and radicals such as CF 3 + did not substantially decay with aging. Since the slopes of linear relationships between logarithmic electrical conductivity (ln ·) and reciprocal temperature (1/T) of all PTFE samples irradiated were approximately equal to that before treatment from 303 to 375 K, HLEBI didn't convert the · system. The small irradiation dose of 0.0432 MGy raised the electrical conductivity at room temperature. At higher temperatures above ³375 K, the 0.0432 and 0.432 MGy-HLEBI generated drops in conductivity ·. When unstable dangling bonds with isolated radicals at terminated sites are assumed to be formed in irradiated PTFE, the · recovery by heating to 424 K as well as high · of irradiated PTFE could be explained. HLEBI probably generated dangling bonds in the form of radicals acting as acceptors to carry charge. Since a chemical dopant was not needed to act as a charge carrier, HLEBI could probably be an attractive method to attain homogeneous doping of organic films.

WITHDRAWN: Effects of Additives and Conductors on Properties of Conducting Porous Composite Based on Activated Carbon

“…Electrical conductivity of AC/BC/PVDF/NMP and AC/BC/PTFE/H 2 O were 1.55 (S/cm) and 0.32 (S/cm), respectively. The cause of the difference in conductivity was explained by the conductivity of the corresponding polymer [12,13]. Therefore, PVDF was selected as the binder for further research.…”

Quinone‐Based Redox Supercapacitor Using Highly Conductive Hard Carbon Derived from Oak Wood

“…This value is much higher than other wood‐derived hard carbons reported so far . On the other hand, the conductivity of A–HC with 10 wt% PTFE is 240 S m −1 despite the very low conductivity of PTFE (5.1 × 10 −17 S m −1 ) . In comparison, the commercial activated carbon with 10 wt% PTFE has a conductivity of 30–60 S m −1 .…”

“…[36] This value is much higher than other wood-derived hard carbons reported so far. [40] In comparison, the commercial activated carbon with 10 wt% PTFE has a conductivity of 30-60 S m −1 . [40] In comparison, the commercial activated carbon with 10 wt% PTFE has a conductivity of 30-60 S m −1 .…”

“…[37][38][39] On the other hand, the conductivity of A-HC with 10 wt% PTFE is 240 S m −1 despite the very low conductivity of PTFE (5.1 × 10 −17 S m −1 ). [40] In comparison, the commercial activated carbon with 10 wt% PTFE has a conductivity of 30-60 S m −1 . [35] This shows that the conductivity of A-HC with 10 wt% PTFE is one order higher than the commercial activated carbon.…”

Evaluating Current Distribution and Influence of Defect Sites for Graphitic Compound Bipolar Plate Materials

“…The same is true for the thin (80 µm thickness) PTFE sheet, which has roughly the same values for all sizes, with the one at 8 mm diameter (50.3 mm 2 area) showing a significantly larger fraction of current at the defect size and the one at 14 mm diameter (153.9 mm 2 area) a significantly lower fraction. Although a good trend can be seen for the thicker PTFE sheet, the values seem to be still quite large, given the fact that PTFE has a very low electrical conductivity of around 5 × 10 −17 S m −1 . Part of this can be explained by the fact that some current flows back into the area of the defect from around it due to the cross‐conductivity of the graphitic BPP material, which is exactly what the BPP is supposed to achieve.…”