Role of macadamia shell nut extracted silicon carbide and natural fiber-reinforced PVA composite and its mechanical, thermal conductivity, dielectric and EMI shielding effectiveness

The present study investigates the role of silicon carbide (SiC) extracted from macadamia nut shells and natural short fibers in reinforcing polyvinyl alcohol (PVA) composites. The composite materials were prepared by integrating SiC, derived through pyrolysis and chemical processing, with PVA and natural fibers to evaluate their mechanical, thermal, dielectric, and electromagnetic interference (EMI) shielding properties. The prepared composites performance is evaluated as per ASTM standard. The result demonstrated that the ideal ratio of matrix, fibers f 40 vol%, and 3 vol% silicon carbide, PCS2 had the maximum tensile strength (142 MPa), tear strength (33 MPa), Izod impact strength (4.7 Joules (J)), and Shore-D hardness (82). Additionally, PCS2 had the highest EMI shielding performance, peaking at 64.84 dB at 18 GHz, as a result of the fibers and fillers working in concert to increase wave absorption and reflection through improved interfacial bonding and polarization. While, the composite PCS3 with reinforcement of 40 vol% of fiber and 5 vol% of SiC shows improved thermal conductivity of 0.23 W/mK, and maximum dielectric permittivity of 4.8 and dielectric loss of 0.73. This work emphasizes the potential of natural fibers and SiC obtained from macadamia shells as high-performance, sustainable fillers in innovative composite materials and it could be applied in areas such as communication, military, signal processing and navigation performance.