Abstract
Purpose This study aims to fabricate a novel electromagnetic interference (EMI) shielding composite aerogel with both thermal insulation and high temperature warning functions. Design/methodology/approach An emerging bio-based polypyrrole (PPy) gel/Fe3O4/calcium alginate (PFC) EMI shielding composite aerogel was prepared by freeze-drying and in situ polymerization method. First, Fe3O4/calcium alginate (CA) aerogel was obtained by freeze-drying the Fe3O4/CA mixture. Then, PPy/Fe3O4/CA was obtained by synthesizing PPy on the surface of CA/Fe3O4 aerogel through in situ polymerization. Finally, PPy/Fe3O4/CA was immersed in porphyrin solution (cross-linking agent) to get the final PFC EMI shielding composite aerogel. Findings Due to the matched impedance between Fe3O4 and PPy, the EMI shielding performance of PFC composite aerogel can reach up to −8 dB. In addition, the PFC EMI shielding composite aerogel also shows excellent self-extinguishing and thermal insulation properties. After leaving the flame, the burning PFC aerogel is quickly extinguished. When the PFC aerogel is placed on the heating plate at 230 °C, the temperature on the side of the aerogel away from the heating plate is only 90.3 °C after 5 min of heating. The electrical resistance of the PFC composite aerogel can be reduced from 3.62 × 104 O to 5 × 102 O to trigger the warning light after 3 s of exposure to the alcohol lamp flame. This reversible thermal resistance response characteristic can be used to give an early warning signal when the PFC encounters high temperature or flame. Originality/value This work provides a novel strategy for designing a multifunctional EMI shielding composite aerogel with repeatable high temperature warning performance. This PFC composite aerogel shows potential applications in the prevention of material combustion in high temperature electromagnetic environments.
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