Anisotropic networking of carbon black in glass/epoxy composites using electric field

This investigation explores the manipulation of carbon black particles for tailoring the electrical properties of unidirectional glass fiber reinforced epoxy composites. Carbon black particles were anisotropically networked along the through-thickness direction of glass/epoxy composite plates using an alternating current electric field applied during curing of the composite, with the objective of maximizing the electrical conductivity through the thickness. Anisotropic networking was observed microscopically and was quantified by measuring the DC electrical conductivity of the cured glass/epoxy composite material in the three principal directions. The effects of carbon black amount, electric field strength, and electric field frequency on the anisotropic conductivity are elucidated using a parametric investigation. It is shown that the through-thickness conductivity can be increased by a factor of roughly 104 relative to the case with no conductivity tailoring and can be of the same order of magnitude as the transverse and longitudinal in-plane conductivities, which are improvements well beyond the studies published until now. Moreover, for the first time, it is shown that the through-thickness conductivity of unidirectional glass/epoxy composites containing carbon black can exceed the in-plane transverse conductivity by selecting appropriate electric field parameters during processing.