Amino-Functionalized DWCNTs Tailor Curing Kinetics and Multifunctional Performance of Epoxy Nanocomposites

The influence of amino-functionalized double-walled carbon nanotubes (DWCNTNH2) on the curing behavior and multifunctional properties of an epoxy resin was systematically investigated. Isothermal FTIR analysis, interpreted using Kamal’s autocatalytic model and model-free isoconversional DSC analysis, showed that the presence of amino-functionalized nanotubes accelerates the initial epoxy curing reaction, increasing the primary reaction rate constant, reducing the activation energy, and confirming the catalytic role of the nanotube surface amino groups. Thermal–mechanical analysis indicated the formation of an interphase characterized by locally reduced crosslink density resulting from reactions between the functionalized nanotubes and the epoxy precursor. This interphase slightly lowers the glass transition temperature and the onset of thermal degradation without significantly affecting the overall thermomechanical performance. The incorporation of the filler also produces a remarkable increase in electrical conductivity, with an electrical percolation threshold between 0.1 and 0.3 wt%. Conversely, moisture diffusion and equilibrium water uptake remain essentially unchanged, demonstrating that the low nanotube content does not significantly alter the diffusion pathways or the polarity of the crosslinked network.