Fabrication of carbon nanotube epoxy prepreg towards lightweight structural composites

Despite improvements in carbon nanotube fiber tenacities, their shear strength continues to limit their performance in composite applications. Shear strength can be improved through resin penetration into the nanotube fiber hierarchical microstructure to enhance internal interfaces. In this work, a manufacturing process uses an ionic liquid and epoxy to simultaneously stretch and infiltrate nanotube roving resulting in a nanotube-epoxy-ionic liquid prepreg. The ionic liquid also serves as a latent curing agent/hardener for the prepreg. After curing, the resulting composite fiber has comparable tenacity and specific modulus to fibers made without epoxy but with improved shear properties. The dry core shear failure mode typically observed in CNT fibers was eliminated and the apparent interfacial shear strength was improved by over an order of magnitude.