Conduction pathways in CNF/PTFE composite: Air oxidized CNFs coated with the incomplete layer of PTFE

Abstract

In the present work, the conduction pathways by air oxidized carbon nanofibers (CNFs) (coated with Polytetrafluoroethylene (PTFE)) dispersed in PTFE polymer have been studied and explored with backbone and dangling ends model. The utility of critical exponents (t) explains the distribution status of CNFs and indicates the possibility of charge transport by ohmic conduction due to connected conducting channels of CNF and tunneling transmission between close CNFs. A 5 wt% sample exhibits a conductivity of 1.91 S/m. Moreover, a cost and material saving method of coating of decomposed PTFE on CNF; regardless of the coating thickness is discussed and studied in order to improve interfacial interaction and dispersion within the polymer without using sonication. Some interesting and informative evidence have also been revealed such as a decrease in d-spacing of 〈002〉 layer of CNF after heat treatment at ~800 °C in air and confirmation of Hexafluoropropylene (HFP) and Octafluoro‑1‑butene (OF1B) thermal products of PTFE on CNFs. The presence and coating of HFP and OF1B were confirmed by FTIR and TEM respectively.