CHARACTERIZATION OF ELECTRICAL CONDUCTIVITY OF A CARBON FIBER REINFORCED PLASTIC LAMINATE REINFORCED WITH Z-ALIGNED CARBON NANOFIBERS

摘要

Traditional carbon fiber reinforced plastics (CFRPs) exhibit high in-plane strength and conductivity due to the orientation of the carbon fibers used as directional reinforcement. However, due to the absence of carbon fiber reinforcement in the through-thickness direction (i.e., z-direction), CFRPs tend to exhibit very poor strength and conductivity in the z-direction. Recently, a novel multiscale CFRP composite was developed using CFRP prepregs containing aligned long carbon nanofibers (CNFs) threading in the z-direction in order to improve the through-thickness mechanical, thermal, and electrical properties that are known to be intrinsic weaknesses of traditional CFRP laminates. The research presented herein specifically focuses on experimentally characterizing and elaborating the effect of CNF z-threads on the through-thickness DC electrical conductivity. The threaded z-aligned CNF network present within the CFRP was hypothesized to provide an electrically-conductive pathway between carbon fibers, thereby improving the through-thickness electrical conductivity of the CFRP laminate. It was further hypothesized that the effectiveness of the electrically-conductive pathway was strongly related to both CNF alignment and CNF concentration (measured as a percentage of matrix weight). To experimentally analyze the impact these factors had on the through-thickness DC electrical conductivity, z-aligned CNF-reinforced CFRP samples with various CNF concentrations were manufactured and compared with unmodified control CFRP samples and unaligned CNF-modified CFRP samples; the concentration of CNF-reinforcement was tested at both 0.1 wt% and 0.3 wt%. The through-thickness DC electrical conductivities were characterized for all samples and the results were compared and discussed against the experimental parameters. It was found that both CNF alignment and CNF concentration had a strong influence on the improvement of through-thickness electrical conductivity of CFRP laminates.