Process Development for Carbon/Epoxy Prepreg Laminates with Magnetically Aligned CNT Interlayers

Carbon fiber reinforced plastics (CFRPs) are widely used in industry due to their high strength-to-weight ratio, and interest exists in improving their mechanical and multifunctional properties. The aerospace industry, in particular, values prepreg CFRPs for their ease of use and superior performance, and carbon nanotubes (CNTs) have shown promise as a multifunctional reinforcement material for CFRPs due to their exceptional nano-scale properties. However, CNT morphology control is required because CNTs tend to agglomerate and that limits their effectiveness as an additive. In this study, we developed a novel approach that involves using a B-staged epoxy film with magnetically aligned CNTs as a method to introduce CNTs into prepreg CFRPs. A hot press and vacuum bag were used to consolidate and cure the laminates. A magnetic field of 180 G was applied at different stages of the laminate fabrication process to effectively align the CNTs while minimizing agglomeration while the polymer is flowing. Laminate properties were assessed through short beam shear (SBS) testing, and although interlaminar shear stress (ILSS) did not significantly improve or degrade, trends regarding magnetic field application in various parts of the process and the effect on ILSS were observed. This knowledge will be used in the future for deciding processing conditions that can maximize mechanical reinforcement with the final goal of attempting to integrate aligned CNTs to the entire prepreg laminate volume. Future work includes further adjustment of magnetic field application for improved CNT distribution, and multi-functional property characterization of CNT-integrated CFRPs.