Role of Magnetic <scp>NiFe</scp> ₂ O ₄ and Conductive <scp>rGO</scp> in Tailoring the Dielectric and <scp>EMI</scp> Shielding Properties of <scp>TPU</scp> Nanocomposite Films

ABSTRACT Thermoplastic polyurethane (TPU)‐based polymer nanocomposites (PNCs) reinforced with reduced graphene oxide (rGO) and nickel ferrite (NiFe 2 O 4 ) nanoparticles were fabricated via a solution casting followed by compression molding. The homogeneous dispersion of rGO sheets and NiFe 2 O 4 nanoparticles within the TPU matrix created multiple heterogeneous interfaces, which facilitated interfacial polarization and magnetic loss mechanisms. Owing to these synergistic effects, the TPU/rGO/NiFe 2 O 4 composite where 5 wt% fixed loading of NiFe 2 O 4 with rGO loading 20 wt% (T‐R20‐N5) exhibited excellent electromagnetic interference (EMI) shielding effectiveness across the X‐band (8.2–12.4 GHz), achieving a maximum total shielding of approximately 20 dB with a low reflection loss of ~3 dB, dominated by absorption. The dielectric constant ( ε ′) reached ~450, indicating enhanced charge transport and interfacial polarization. Furthermore, the nanocomposite demonstrated superior mechanical strength, with a tensile stress of 27 MPa, attributed to efficient stress transfer through the interconnected rGO‐NiFe 2 O 4 network. These results highlight the potential of TPU/rGO/NiFe 2 O 4 nanocomposites as lightweight, flexible, and broadband EMI shielding materials combining high dielectric performance, strong mechanical resilience, and low reflection—suitable for next‐generation aerospace, electronics, and wearable applications.