Phenolic Resin Composites for EMI Shielding: Strategies Toward Future Aerospace Requirements

The rapid advancement of aerospace technology demands electromagnetic interference (EMI) shielding materials that maintain reliable performance under severe thermo-mechanical conditions, such as sustained high temperatures and thermal shock. Phenolic resin (PR) stands out as a highly suitable matrix material, especially for carbon-based composites, thanks to three key features: (i) good thermal stability from high char yield. (ii) strong ability to combine with various functional fillers. This review introduces the basic principles of EMI shielding and explains the influence of phenolic resin's structural designability on shielding performance. Furthermore, it addresses two primary strategies: intrinsic shielding via molecular backbone modification of PR, and composite shielding by incorporating new functional fillers. On this basis, the concept of multifunctional collaborative design is further proposed, which integrates EMI shielding with high-temperature resistance, thermal insulation, ablation resistance and mechanical load-bearing properties to match the complex extreme service requirements of aerospace scenarios. Both approaches and their synergistic extension toward multifunctionality are examined systematically. In summary, although PR-based composites outperform conventional polymers in high-temperature EMI shielding, they still face major challenges: filler-matrix interfacial problems and insufficient validated in situ high-temperature performance data, which need to be solved for practical deployment from lab prototypes.