Comparative Effects of Alkali Treatment on the Physical, Mechanical, and Morphological Properties of Natural Fiber for Preliminary Insulation Material Screening

Abstract

The effects of alkali treatment were studied relative to the physical, mechanical, and morphological properties of oil palm empty fruit bunch (OPEFB) and banana fibers to evaluate their potential as insulation materials. Both fibers were subjected to several concentrations of sodium hydroxide (3, 6, and 9 wt%). The impact of altered fibers was assessed using image analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), tensile testing, and thermal characterisation. The diameters of both fibers were decreased post-treatment, along with reductions in lignin and hemicellulose contents inside the fibers. Tensile strength was enhanced by 29% to 177% with 3% alkaline treatments for both fibers, while 6% alkali treatment yielded superior results for both fibers. The NaOH-treated OPEFB and BF exhibited increased residual content after thermogravimetric analysis and enhanced thermal stability. SEM analysis revealed that 3% alkali treatment eliminated silica bodies from OPEFB fiber, but 6% alkali treatment consistently filled the porosity of BF. The results implied that alkali treatment of OPEFB fiber significantly enhanced compatibility and mechanical properties, whereas treated BF had improved thermal stability for the manufacture of composite materials. Thus, alkali treatment effectively enhanced OPEFB and banana fibers, making them promising candidates for insulation material applications.