Ferrocene decorative phenolic epoxy resin as lightweight thermal-stable dielectric relaxor for electromagnetic wave absorption

Abstract

Given the severe electromagnetic (EM) energy wasting and radiation interference, it is critically regarded to develop EM absorbing materials. In this work, a new type of lightweight heat-resistant polymer-based dielectric relaxor was manufactured as an efficient electromagnetic absorber by ferrocene (Fc) decorative phenolic epoxy resin (EPN) ferroelectric. A series of resin samples have been obtained as different amount of hydroxyethyl ferrocene (Fc-OH) was taken part in the EPN curing systems with 4,4′-diaminodiphenylmethane (DDM) as curing agent. Finally, the obtained results indicated that the EPN was gradually transformed into a typical relaxor ferroelectric from normal ferroelectric with the increasing amount of Fc decoration. The thermal stability was greatly optimized as the onset temperature of thermal decomposition was increased to 245 °C. It was confirmed that the optimized dielectric properties have strengthened the impedance matching and polarization relaxation behavior, which resulted in excellent EM dissipation. In details, the minimum reflection loss (RLmin) of EPN with 15 wt% Fc decoration reached -30.79 dB with an effective absorption band (fE) of 3.92 GHz at 1.9 mm and the maximum fE was 4.08 GHz at 2.00 mm. It is worth emphasized that the matching thickness was effectively decreased by modification of Fc moieties. Therefore, this research provides an effective path for EM absorption, opening up novel ideas for exploration of lightweight high-performance polymer-based EM absorbers.