Effect of curing on activation energy and dielectric properties of carbon black–epoxy composites at different temperatures

•We studied curing effect on the activation energy & dielectric properties of CB–EP composites.•Thermal curing reduces the activation energy.•Activation energy decreases with an increase in the concentration of CB in the composite.•Cured EP–CB composite shows increased dielectric constant (ε′).•Effects of frequency, temp. & volume concentrations were studied on dielectric properties.

The effect of curing on activation energy and dielectric properties of carbon black–epoxy (CB–EP) composites has been reported at different temperatures and frequencies. The activation energy was found to be higher for the room temperature cured CB–EP samples as compared with the thermally cured CB–EP samples. Curing behavior of epoxy nanocomposites prove that epoxide molecules contribute to the curing reaction and reacted with them to form a cross-linked network. Dielectric constants of thermally cured CB–EP samples were higher than the room temperature cured samples. The results showed that activation energy, decreased with an increase in the concentration of carbon black in the composite, which may be due to an increase of polarization energy and/or charge carrier density leading to a decrease of the domain boundary potential of carbon black aggregates into the epoxy matrix. At room temperature, the electrical conductivity is due to electron tunneling and hopping. Dielectric constant of the CB–EP composite increase with increase in temperature and decreases with an increase in frequency from 0.5 kHz to 10 kHz for both room temperature cured and thermally cured specimens. The peak height of the dielectric constant curve of both cured samples decreases with increasing frequency.

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