Preparation of dual-functional polymer composite for enhanced thermal insulation and microwave absorption

Carbonyl iron powder (CIP) exhibits excellent performance in absorbing waves, but the high thermal conductivity limits its engineering applications in safe thermal protection. This study proposes an integrated material design strategy based on interface engineering. Hollow glass microspheres (HGMs) and CIP are chemically coupled to create a micro-resonator network with thermal insulation properties. The effects of functional filler on thermal insulating and microwave absorption properties were systematically studied. The results show that the composite material demonstrates excellent microwave absorption performance, with a reflection loss (RL) of -33.96 dB at an addition of 30%. When the addition is increased to 40%, the microwave absorption performance of composite material decreased. However, the thermal conductivity is only 0.12128 W/(m·K) and the composite material shows excellent flame retardancy due to the structural characteristics of HGMs. The efficient integration of heat insulation and wave absorption performance was successfully realized through an ingenious interface structure design.