Green Biocomposites From Agro‐Waste With Central Layer Architecture: A Performance Comparison Against Glass Fiber Composite

This study develops and evaluates green biocomposites using agro‐waste fibers, maize husk fiber composite (MFC), luffa fiber composite (LFC), and betelnut husk fiber composite (BFC) as core reinforcements in a central‐layer unsaturated polyester resin (UPR) matrix, comparing their performance with a 5% glass fiber composite (5% GFC) and neat UPR. Fibers underwent alkali treatment to enhance interfacial adhesion beforehand lay‐up fabrication. The composites were characterized via structural, mechanical, physical, thermal, and morphological analysis. Among the natural fiber systems, tensile (20.68 MPa) and compressive (87.6 MPa) strengths were highest for the BFC. LFC showed superior flexural strength (48.83 MPa) and microhardness (14.2 HV). MFC exhibited the highest impact strength (0.34 kJ m −2 ) and ductility (7.64% elongation). Natural fiber composites showed lower strength than glass fiber in all tests except hardness, and lower tensile and flexural strength than neat UPR. All agro‐waste composites exhibited greater water uptake (up to 1.524%) and biodegradability (0.00072% mass loss) than neat UPR, but the central layer structure seemed protecting the natural reinforcements from the environmental effects. Thermal analysis revealed improved char yield in natural fiber systems, and confirmed that fiber addition (0.310–0.361 W m −1 K −1 ) had minimal effect on heat transfer, indicating matrix‐dominated thermal behavior across all composites. Scanning electron microscopy (SEM) indicated weaker interfacial bonding compared to GFC. The work demonstrates the potential of central‐layer agro‐waste biocomposites as sustainable structural materials for automotive interiors, panels, and lightweight construction, with competitive functional properties and improved environmental performance. Future research should optimize fiber treatment, loading, and hybridization to enhance interfacial bonding and durability for broader engineering applications.