Flexible metal foil/polymer sandwich composites for electromagnetic interference shielding with anti-wind–sand environment tolerance

In the anti-wind–sand environment, it is challenging to find a single material that fulfills all the required functional application requirements, such as shielding performance, mechanical performance, chemical performance, reliability, and economic efficiency. Herein, a multi-layer electromagnetic shielding composite sheet specifically was designed for large military bases in anti-wind–sand environments. The composite material structure comprises laminated aluminum foil, PET film, and Oxford fabric, utilizing an acrylic emulsion pressure-sensitive adhesive that was modified with superior nano-SiO₂. The results showed that the electromagnetic interference shielding of Al Mylar foil (0.03 mm) measured 88 dB, whereas the medium gauge foil recorded 84.7 dB after salt spray test for 288 h. The samples of Oxford fabric showed an increase in tensile and tearing strength as the fabric density increases, but the rate of increase decreases gradually. The shear and peel strengths of acrylic emulsion modified by hydrophobic nano-SiO₂ were 67.1 MPa and 24.3 N/m, respectively, with a blending ratio of 7 wt%. Finally, we handpicked 140 g/m² of Oxford cloth, 0.03 mm of aluminum foil with PET films, and acrylic emulsion pressure-sensitive adhesive containing 7 wt% hydrophobic nano-SiO₂ for the lamination. The samples have good aging performance, with electromagnetic shielding performance, shear strength, peel strength, and weight loss declining less than 10% at 85 °C and 85% RH for 1000 h.