Amino-Functionalized Carbon Nanotubes For Effectively Improving The Mechanical Properties Of Pre-Impregnated Epoxy Resin/Carbon Fiber

Pre-impregnated carbon fiber/epoxy resin (CF/epoxy prepreg) gained its popularity for significant stress applications, especially in the aerospace industry, owing to its excellent resistance and low specific mass. However, these CF/epoxy prepregs have a tendency to crack propagation. A solution for the prepregs fragility is the addition of carbon nanotubes (CNTs), especially those functionalized with amino groups, reinforcing the material due to its exceptional mechanical properties. In this work, the influence of the carbon chain length of two different amino-functionalized CNTs from diverse backgrounds (commercial and laboratory growth CNTs) is studied. The nanofillers were added in CF/epoxy prepregs by dry spraying without solvent aid. CNTs' samples were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis (TGA), while the composites were analyzed by TGA, dynamic-mechanical analysis, and field emission scanning electron microscopy. The various surface treatment occurred at different levels according to the CNTs background, and all samples exhibited a distinct behavior. These differences were also observed in the composites' thermomechanical performance: CNTs functionalized with larger carbon chain amine presented the best results, with an increase of almost 100% in the storage moduli (E'), confirming the efficiency of amino-functionalized CNTs in the reinforcement of CF/epoxy prepregs.