Development of Porous Biocarbon from Waste Wild Jack Husk for Enhanced EMI Shielding and Mechanical Performance in Wheat Straw Microfiber-Reinforced Vinyl Ester Composites

Abstract

This study focuses on the development and characterization of a vinyl ester composite reinforced with surface-modified biocarbon derived from wild jackfruit husk and silane-treated wheat straw microfibers. The vinyl ester resin was selected for its favorable properties, such as low shrinkage during curing. Biocarbon was extracted from wild jackfruit husk through a slow pyrolysis process, resulting in fine particles with an average size of 80 µm. These biocarbon particles, along with wheat straw microfibers, were subjected to silane treatment to enhance interfacial bonding with the vinyl ester matrix, which improved mechanical properties and particle dispersion. Composite specimens were fabricated with varying biochar content (1, 3, and 5 vol.%) and a constant 40 vol.% of silane-treated wheat straw microfibers. Among the composites, VMF5 (3 vol.% silane-treated biochar) exhibited the best overall performance. These improvements are attributed to the optimal balance between the biochar’s conductive nature and the enhanced interfacial bonding from the silane treatment, which also contributed to superior dielectric permittivity, with values such as 6.1 at 8 GHz and 2.7 at 18 GHz. Additionally, VMF5 demonstrated the total shielding values of 31.5 dB at 8 GHz and 68.3 dB at 18 GHz. SEM analysis provided further insights, revealing well-dispersed biochar particles and strong fiber–matrix adhesion, which were crucial in enhancing the composite’s mechanical and shielding properties. The findings underscore the effectiveness of silane treatment in improving the performance of biochar-filled composites and position VMF5 as a highly promising material for applications requiring robust mechanical, dielectric, and EMI shielding properties.