Enhanced Electromagnetic Interference Shielding Performance in Multilayered Thermotropic Polyarylate Composites Reinforced with Carbon Nanotubes, Carbonyl Iron Particles, and Carbon Fibers

The development of lightweight, thermally stable, and high-performance electromagnetic interference (EMI) shielding materials is critical for next-generation electronic applications. In this work, thermotropic polyarylate (TP)-based composites reinforced with 3 wt % carbon nanotube (TCNT3), 5 wt % carbon fibers (TCF5), and 80 wt % carbonyl iron particles (TCIP80) are fabricated via melt compounding, hot-pressing, and multilayer stacking. Microstructural analyses reveal well-dispersed fillers with strong interfacial adhesion to the TP matrix and seamless interlayer welding in heterogeneous multilayered structures. Electrical conductivity measurements show significant enhancements with filler incorporation, with values of 7.4 × 10^-11, 9.0 × 10^-8, and 2.7 × 10^-3 S/cm for TCNT3, TCIP80, and TCF5, respectively, compared to pristine TP. Correspondingly, the thickness-normalized shielding effectiveness (<i>SE</i>_tot/<i>t</i>) in the X-band frequency of 8-12 GHz increases from ∼5 dB/mm for pure TP to ∼25.9 dB/mm for TCF5. The three-layered composite (L-TPF), comprising sequential layers of TCNT3, TCIP80, and TCF5, exhibits the highest shielding performance of an average <i>SE</i>_tot/<i>t</i> of 31.8 dB/mm, representing a 23% enhancement over the best-performing single-filler system. This improvement in the three-layered composites is attributed to synergistic absorption-reflection mechanisms, impedance mismatch at interlayer boundaries, and magnetic loss contributions from the centrally positioned TCIP80 layer. The transmission coefficient further confirms that L-TPF suppresses incident wave propagation nearly 4-fold compared with TCF5. These findings highlight multilayered TP composites as lightweight, thermally robust, and tunable materials with significant potential for enhanced EMI shielding applications in electronic applications.