Processing and characterization of carbon nanoparticle/fiber-reinforced polymer composites

Abstract

Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have an exceptional combination of properties that make them ideal materials for use as reinforcing particles in advanced composites. This investigation was aimed at obtaining fundamental understanding of the processing and properties of carbon nanoparticle/fiber-reinforced polymer composites ―defined as multiscalereinforced polymer composites (MRPCs)― manufactured through a practical and scalable process. Such process consists of two stages. The first stage involves the synthesis of multiscalereinforcement fabrics (MRFs) by electrophoretic deposition of carboxylic acid- or aminefunctionalized CNTs and CNFs onto the surface of carbon fiber layers in aqueous medium; while the second stage proceeds with the stacking of the MRFs and infusion of the resulting preforms with an epoxy-amine resin system to obtain the MRPC. MRPCs manufactured following the described approach were tested for mechanical and electrical properties. Mechanical test results showed an increase in interlaminar shear strength (ILSS), shear stiffness, and compressive strength of all panels manufactured. Panels containing amine-functionalized carbon nanoparticles had the highest increase in properties: 13% in ILSS, 2.5-4 fold in shear stiffness, and up to 15% in compressive strength. On the other hand, it was found that through-plane electrical conductivity of MRPCs increased by 100% when using unsized MRFs. Investigation into the enhancement mechanism of mechanical and electrical properties was also performed. Discussion of these mechanisms are presented with emphasis placed on the fiber/matrix interface and the load transfer mechanisms between matrix, carbon nanoparticles, and carbon fiber.