Ultra-low percolation threshold in epoxy resin–onion-like carbon composites
Résumé
This paper deals with dielectric/electrical properties of composite films based on onion-like carbon (OLC) as filler in an epoxy resin matrix. The measurements were carried out in a very broad range of frequencies (20 Hz–34 GHz), and the results show that the percolation threshold in these composites is related to the size of the OLC aggregates, the biggest aggregates leading to the lowest threshold (0.7 vol. %). The observed critical exponent reasonably agrees with the theoretical value. Composites comprising 10.89 vol. % of 250 nm-big OLC aggregates exhibit dielectric permittivity as high as 60 000 and electrical conductivity as high as 0.05 S/m at 20 Hz.
The authors gratefully acknowledge the financial support of “Gilibert” PHC exchange project “Dielectric and electric properties of hollow carbon spheres and mesoporous carbon between Lithuania and France”.