Effect of Bending Load on the Electrical Conductivity of Carbon/Epoxy Composites Filled with Nanoparticles

Hypothesis: The purpose of this study was to investigate the effect of bending load on the electrical conductivity of carbon-epoxy composites containing various nanoparticles. The developed samples, while having sufficient flexural strength, must have the electrical conductivity proposed by the U.S Energy Institute to be used in the manufacturing of electrodes. Methods: For this purpose, carbon black nanoparticles, carbon nanotubes and expanded graphite with unidirectional carbon fabrics and epoxy resin were used to make the samples. Carbon black particles, carbon nanotube and expanded graphite with optimum weight percentages (25, 10 and 15%) were added to carbon/epoxy composite and the electrical conductivity threshold of the samples was measured according to the four-point strength method. The average electrical conductivity permeability threshold for composites containing carbon black, expanded graphite and carbon nanotubes was 23.2, 27.3 and 24.7%, respectively. The samples were then subjected to bending load and for the 0.5, 1, 1.5, 2 and 2.5 mm transverse displacement, the electrical conductivity value was measured during loading and unloading. Findings: The results showed that the value of electrical conductivity loss in carbon/epoxy samples containing carbon nanotubes caused by bending was at lowest and in the carbon/ epoxy containing carbon black samples displayed the highest value. Then, the flexural strength of the specimens was measured using a three-point bending test method. The pattern of nanoparticle distribution in the samples was studied on images acquired by scanning electron microscope images. The result of this research could be used in manufacturing of composite electrodes which are subjected to flexural loading (electrostatic desalting crude oil tanks) in services.