Conductive Network Enhanced Carbon Black/Epoxy Composite Coating with Imide Curing for Antistatic and Heat-Resistance Improvement

Abstract

Epoxy resins are essential in aircraft coatings due to their strong mechanical properties and corrosion resistance. However, their limited high-temperature resistance restricts their use in high-speed aircraft, particularly for anti-static and electromagnetic-shielding coatings, which incorporate conductive networks. The dispersion of conductive fillers is hindered by the crosslink network of epoxy resins. Here, we developed a mixture curing system combining diethylenetriamine and dicarboxylic phthalimide. This system allows imide to copolymerize with the epoxy resin, enhancing temperature resistance and optimizing the dispersion of fillers by adjusting the densities of chemical and physical crosslinks. Our results indicate that the decomposition temperature of the epoxy composite increases to 383.8 °C, suitable for aircraft exceeding Mach 3 speeds. Additionally, the percolation threshold for carbon black fillers in this system is 8.1 vol%, significantly lower than the ca. 70% in volume-exclusion systems. This reduction is primarily due to the liberation of epoxy resin segments from the chemical crosslink network. The electrical performance is also notable, with volume resistivity dropping to 0.2 Ω·m near the percolation threshold, meeting anti-static product requirements. This advanced epoxy resin system shows promise for use in electromagnetic coatings on aircraft, given its enhanced temperature resistance, anti-static properties, and mechanical strength.