Excellent Microwave Absorption of Polyurethane Nanocomposites Engineered With Graphene Nanoplatelets and Magnetite

The escalating growth in telecommunication technology has led to a surge in electromagnetic pollution due to the increase in electronic devices. This not only impacts the performance of electronic gadgets but also poses risks to human health. To counteract electromagnetic pollution, researchers have extensively investigated microwave absorbers. As communication technologies predominantly operate in the microwave region, demand for efficient microwave‐absorbing materials is rising. Traditional metal‐based microwave absorber materials face limitations in terms of cost, density, corrosiveness, and rigidity, prompting attention to polymer‐based composites, among which polyurethane (PU) composites stand out for their exceptional properties, making them a favorable candidate for microwave absorption applications. This study explores the microwave absorption performance in the X‐band frequency (8.2–12.4 GHz) of PU nanocomposites containing graphene nanoplatelets (GNP) as a conductive filler and magnetite as a magnetic filler. Various loading percentages of GNP and magnetite were incorporated into both rigid polyurethane (RPU) and flexible polyurethane (FPU) matrices. The optimized composition of 2.5% GNP and 2.5% magnetite (1:1 ratio) exhibited superior microwave absorption properties, achieving a minimum reflection loss of −39.2 dB with an effective absorption bandwidth of 1.22 GHz in RPU, and −26.5 dB with an EAB of 1.52 GHz in FPU. These results highlight that the synergistic combination of conductive and magnetic fillers within PU matrices provides an efficient pathway for designing lightweight, cost‐effective, and high‐performance microwave absorbers.