Palmyra Palm Shell (Borassus flabellifer) Properties Part 3: Insights Into Its Morphological, Chemical, and Thermal Properties After Alkali Treatment

Abstract

The demand for materials that combine high thermal stability and environmental sustainability is growing in modern engineering. While synthetic fibers are effective, their environmental impact often undermines sustainability goals. This study explores the potential of Borassus flabellifer fruit husk, typically discarded as agricultural waste in Bangladesh, as a bio-fiber alternative for thermal insulation applications. The research investigates the morphological, chemical, and thermal properties of the husk after alkali treatment with sodium hydroxide (NaOH) for varying durations. The results show that alkali treatment significantly enhances the thermal properties of Borassus husk. Notably, char content increased by up to 32%, surpassing other biofibers such as hemp, sisal, jute, and kenaf. The integral process decomposition temperature (IPDT) was found to be up to 30% higher than the untreated husk fiber, indicating improved thermal stability. Additionally, specific heat capacity (Cp) decreased by approximately 37%, correlating with an increase in integral process decomposition heat (IPDH). Scanning electron microscopy (SEM) analysis revealed that treated husks had a rougher and cleaner surface, which may improve thermal insulation properties by creating more voids and enhancing adhesion in composite materials. Fourier Transform Infrared Spectroscopy (FTIR) analysis showed reduced and shifted hemicellulose peaks, consistent with lower moisture absorption, as confirmed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Optimal results were observed in samples treated for 0.25 and 0.75 h, suggesting that alkali-treated Borassus husk could serve as an alternative eco-friendly material for energy-efficient and sustainable engineering applications.