Fabrication and Characterization of Carbon Nanotube/Bismaleimide Nanocomposite Laminates with Ultrahigh Nanofiber Volume Fraction

Abstract

With their high mass-specific mechanical properties including elastic modulus and strength, as well as high electrical and thermal conductivity, aligned carbon nanotubes (CNTs) are advantaged candidates as reinforcements for polymer nanocomposites (PNCs) that could enable various structural and multifunctional applications. To achieve enhanced polymer nanocomposite properties, uniform distribution, and dense packing of the aligned CNTs are desired. Previous approaches for making CNT-reinforced PNCs often resulted in low CNT packing density (< 10 vol%), CNT agglomerations, random morphologies, and inhomogeneous nanofiber distribution, making it difficult to realize predicted property enhancements. In this study, we demonstrated a novel bulk nanocomposite laminating (BNL) process that enables scalable fabrication of CNT-reinforced PNC plies and laminates with uniform CNT distribution and a nanofiber packing density exceeding 50 vol%. CNT/Bismaleimide (BMI) polymer nanocomposite laminates with CNT volume fractions ranging from ~ 37 to 52 vol% were fabricated, and their process-structure-property relationships are investigated using techniques including scanning electron microscopy, X-ray micro-computed tomography, thermogravimetric analysis, and tensile testing. The knowledge obtained from this study will also provide insight into the effect of high CNT packing density (> 50 vol%) on various properties of aerospace-grade bismaleimide thermoset resins, which will support the design of next-generation PNCs with high CNT packing density for further enhancement of mechanical and multifunctional properties.