Nanoengineered polyaniline/carbon black VXC 72 hybridized with woven abaca for superior electromagnetic interference shielding

The growing demand for efficient electromagnetic (EM) shielding materials has driven extensive research into sustainable and functionalized composites for high-frequency applications. This study investigates the electromagnetic (EM) shielding properties of Polyaniline (PAni)-functionalized woven abaca fibers, reinforced with Carbon Black (CB) VXC 72, in the ultrahigh-frequency (UHF) range (500-4500 MHz), as determined using Vector Network Analyzer (VNA). The composite was developed by functionalizing abaca fabric with PAni through in situ chemical oxidative polymerization and depositing CB via a dip-and-dry method. The morphological structure and elemental composition were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), while Fourier-transform infrared (FTIR) spectroscopy was used to confirm functional group interactions. Electrical resistivity was determined using the four-point probe method, and EMI shielding effectiveness (SE) was evaluated in the ultrahigh frequency (UHF) range of 500 MHz to 4500 MHz using a Vector Network Analyzer (VNA). Experimental results indicate that PAni/CB functionalization successfully imparted shielding properties to abaca fabric. PAni/1CB/Abaca exhibited the highest shielding effectiveness with an average SE of 5.96 dB, corresponding to 74.34% attenuation of incident electromagnetic waves, and a peak attenuation of 7.45 dB at 4.5 GHz. In contrast, 2CB/Abaca and PAni/2CB/Abaca showed selective EMI shielding, with peak attenuation values of 8.27 dB at 1.67 GHz and 7.98 dB at 1.69 GHz, respectively. The electrical resistivity measurements revealed that PAni/1CB/Abaca had the lowest resistivity at 891 Ω·cm, whereas 1CB/Abaca exhibited the highest at 5238 Ω·cm. The primary shielding mechanism was absorption rather than reflection, making the composite a lightweight, corrosion-resistant alternative to traditional metal-based EMI shields. These findings demonstrate the potential of natural fiber-based conductive composites for flexible EMI shielding applications in telecommunications, healthcare, and aerospace industries.