Role of hybrid magneto-electric Fe 2 SO 4 /biocarbon on electrical conductivity, magnetic permittivity, and electromagnetic interference shielding properties of flexible PVA composite

This study investigates the influence of silane-treated loofah vine stem microfiber and hybrid magneto-electric fillers (Fe 2 SO 4 and biocarbon) on the electrical, magnetic, and electromagnetic interference (EMI) shielding properties of flexible PVA-based composites. The electrical conductivity increased significantly with hybrid filler loading, and among all specimens, PLF2 exhibited the most balanced and efficient conductive response, reaching 6.5 × 10 −9 S/m, which is 6.5 × 10 6 % higher than neat PVA. This enhanced conductivity is attributed to the formation of semi-continuous conductive networks created by 1.5 vol.% Fe 2 SO 4 and 1.5 vol.% biocarbon, supported by silane treatment that ensures uniform dispersion and low interfacial resistance. Magnetic measurements revealed progressive increases in both real (µ′) and imaginary (µ″) permeability with higher Fe 2 SO 4 content, where PLF3 recorded the highest values—µ′: 3.24–4.20 and µ″: 0.64–1.49—due to the formation of dense magnetically responsive micro-domains that promote domain wall relaxation, dipole rotation, and interfacial polarization. EMI shielding performance followed a similar trend, with PLF3 achieving the maximum SE, ranging from 8.89 dB (E-band) to 30.06 dB (J-band), owing to the synergistic combination of conduction loss from biocarbon, magnetic loss from Fe 2 SO 4 , and multiple reflection pathways created by the fiber network. Overall, the hybrid reinforcement system demonstrates strong potential for flexible EMI shielding applications, with PLF2 being optimal for conductivity-driven designs and PLF3 excelling in magnetic and EMI attenuation mechanisms. This composite show potential for flexible EMI shielding, wearable electronics, sensors and energy storage applications.