Abstract
Bio-based materials are gaining importance in engineering due to their availability, recyclability, and eco-friendliness. Among them, Borassus flabellifer (Palmyra palm) fruit shell (husk) is an underutilized biofiber in Bangladesh, currently limited to disposal or waste-to-energy applications despite its potential for high-value uses. This study explores the physical, chemical, and microstructural properties of untreated Borassus flabellifer husk to evaluate its suitability as a sustainable material for engineering applications. The physical properties, including density, water absorption, moisture regain, and porosity, were assessed according to BS EN ISO 1183-1:2019, ASTM D750, ASTM D2654-22, and ISO 2738 standards. The husk was found to be significantly lighter than its fine as well as coarse fibers and conventional natural fibers like jute, flax, and sisal, making it ideal for lightweight engineering designs. FTIR analysis (qualitatively) revealed the presence of cellulose, hemicellulose, and lignin, which contribute to its mechanical strength, water absorption, and thermal insulation properties, respectively. SEM analysis further demonstrated a cross-linked, porous, and tubular fiber structure, enhancing its thermal and sound insulation features. The findings suggest untreated Borassus flabellifer husk can be a promising alternative for applications requiring lightweight, thermally, and acoustically insulating materials. While its moisture and water resistance outperform some biofibers, chemical treatments could enhance these properties further. To maximize its potential, efficient collection and supply chain systems are essential for industrial-scale production. Harnessing this abundant resource could support sustainable development while encouraging the cultivation and preservation of Borassus flabellifer trees.