Abaca Fiber as a Potential Reinforcer for Acoustic Absorption Material at Middle-High Frequencies

Recently, abaca fibers have become the focus of specialized research due to their intriguing characteristics, with their outstanding mechanical properties being a particularly notable. In the conducted study, the abaca fibers underwent a preliminary treatment process involving an alkaline solution, which was composed of 0.5% sodium hydroxide (NaOH) and 50% acetic acid (CH₃COOH). This process entailed immersing each fiber in the solution for a period of one hour. This treatment led to a 52.36% reduction in lignin content compared to the levels before treatment, resulting in a dramatic decrease in the full width at half maximum (FWHM) in the XRD spectra from 1.13 to 0.13. This change indicates that the fibers became more crystalline following the treatment. The abaca fibers were also characterized using BET (Brunauer Emmett Teller) measurements, which revealed that the average pore length ranged from 33–49 nm and the surface area was between 13–28 m^2·g−1. The morphology of the abaca fiber after alkali an hydrolisis treatment (AFAH) appeared rougher and more uniform. DMA measurements revealed a significant rise in the storage modulus of the single fiber post-treatment, with dependencies on both frequency and temperature. AFAH exhibited an optimal absorption coefficient of α = 0.9 for frequencies above 2500 Hz. The combined effect of alkalization and hydrolyzation treatments, while resulting in an enhancement in the mechanical properties of the fibers, also reduced high-intensity noise produced by sources such as machin-ery, aircraft takeoffs and landings, etc., across a broader working frequency range.