Multilayered frequency-selective and high-performance electromagnetic interference shielding materials derived from waste polyurethane foam†

The development of electromagnetic interference (EMI) shielding composites with tunable frequency-selective shielding attributes is of critical importance for their applications in military and signal detection fields. This study introduces a multilayered conductive polymer composite comprising waste polyurethane foam (WPUF), ground tire rubber (GTR) powders, carbon nanotubes (CNTs) and cellulose nanofibres (CNFs). The bulky waste polymeric material with a porous structure, WPUF, is utilized as the substrate to construct the rationally designed alternative conductive-insulating multilayered structure, which significantly enhances the multiple-reflection of the incident EM wave. This conductive composite provides enhanced EMI shielding effectiveness and unique tunable frequency-selective EM shielding performance. The EMI shielding peak shifts with the variation of CNTs, and adjusting the GTR/WPUF ratio in the insulating layer enables fine-tuning of its selective EMI shielding performance over a specific frequency range. In addition, the composite demonstrated robust durability, which benefits its practical application. This approach proposes a practical and innovative method for the design and fabrication of advanced frequency-selective EMI shielding composites with bulky polymer wastes.