Four Probe Electrical Resistance Characterization of Carbon Fiber and Carbon Nanotube Buckypaper Composites

摘要

In this work, the electrical resistance of carbon fiber reinforced polymer (CFRP)and carbon nanotube buckypaper (BP) composites has been studied. The specimenswere prepared according to three different layup configurations. Three 16-plyunidirectional carbon fiber (CF) composites IM7/977-3 [0]16T, or CF16, were preparedand used as the baseline for the study. Additional specimens were prepared with theaddition of 4 and 7 layers of BP. Experimental measurements of the electricalresistance have been performed using two methods. In the first method, six probeswere attached to the top and bottom of the specimens and measurements wereperformed using the traditional 4-probe electrical resistance method (i.e. the electrodesspan the entire width of the specimen) for composite laminates. The second methodwas based on a modification of the four-point probe method of the Japanese IndustrialStandard (JIS) K7194. Results were analyzed in order to observe the effects of thehighly conductive buckypaper on the overall resistance of the composite laminates aswell as to illuminate any trends between the number of BP layers added and theresulting changes to electrical resistance.The specimens with layers of BP were found to have lower resistance comparedto the specimens with no BP. Moreover, as the number of BP layers increased from 4to 7, the resistance continued to decrease. These results demonstrated two significantfindings. First, the current not only flowed through the top CF layer but penetratedthrough the thickness, as evidenced by the lower resistance measured on thespecimens with BP. Second, the decrease in resistance between the specimens with 4and 7 layers of BP measured by the traditional 4-probe electrical resistance methodwas greater than predicted by finite element analysis (FEA) due to nonlinear edgeeffects. The method based on the JIS K7194 was found to reduce the influence of edgeand geometry effects on resistance.