Alkali-treated Borassus Husk Fibre Reinforced High-heat Resistant Epoxy Composites: Insights into Their Thermal, Dynamic Mechanical and Outgassing Properties

Natural fibres from renewable resources offer a sustainable and biodegradable alternative to synthetic reinforcements. This study investigates the thermal and mechanical properties of Borassus husk fibre/epoxy composites, fabricated via the hand layup process using 5% NaOH alkali treatment at varying durations (0.5-2 hours). Their thermal and thermo-mechanical properties were investigated through thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) followed by outgassing test. Results indicate that alkali treatment significantly enhances the thermal stability of the composites, as evidenced by increased char content (up to 8.11%) and higher integral procedural decomposition temperature (IPDT), with the 0.75-hr treated fibre/epoxy achieving the highest IPDT (525°C). The composites also demonstrated superior energy dissipation and mechanical stiffness compared to neat epoxy (NE) and other bio-fibres based composites. The glass transition temperature (Tg) decreased from 150°C (NE) to 126°C (0.5TBHFE)-137°C (0.75TBHFE), yet outperforming composites reinforced with other conventional natural fibres. Additionally, storage modulus and damping factor (tan δ) improved significantly, with 0.5TBHFE exhibiting the best balance between stiffness and damping. The total mass loss (TML) from outgassing test was increased (0.7-0.89%) considerably compared to NE (0.26%), still confirming acceptable thermal stability. These findings suggest that alkali-treated Borassus husk fibre/epoxy composites offer excellent thermal resistance, mechanical strength and impact resistance, making them promising materials for high-performance applications in the aerospace industries, which would also promote sustainable development. However, variations in properties of biofibres require further research, along with the development of an efficient supply chain for industrial-scale production.