Electromagnetic shielding effectiveness of lyocell/nettle Fiber–Biocarbon reinforced vinyl ester composites

This study reports a novel silane-treated hybrid composite combining Lyocell and nettle fibers with Nypafruticans seed shell–derived biocarbon in a vinyl ester matrix. Composites were fabricated with a fixed fiber loading of 40 vol.% in an alternating stacking sequence, while biocarbon content was varied from 2 to 8 vol.% to tailor multifunctional performance. The composite with 4 vol.% biocarbon exhibited optimum mechanical properties, achieving tensile strength of 135 MPa, flexural strength of 151 MPa, impact energy of 3.58 J, and hardness of 83 Shore D due to enhanced interfacial bonding and efficient stress transfer. The composite containing 8 vol.% biocarbon showed superior dielectric permittivity (5.23), EMI shielding effectiveness (33.12 dB in the J-band), and thermal conductivity (0.58 W/mK), attributed to continuous carbon-rich conductive networks. Scanning Electron Microscopic (SEM) analysis confirmed improved matrix–fiber adhesion with localized filler agglomeration at higher loadings. The developed hybrid composite is suitable for lightweight structural applications such as automotive interiors, construction panels, and consumer casings due to its enhanced mechanical performance at optimal biocarbon loading. At higher biocarbon content, it is ideal for EMI shielding, electronic enclosures, and thermal management systems owing to its improved dielectric, conductive, and heat dissipation properties.