The chemical, morphological, physical, and thermal properties of raw materials and single fibers extracted from different morphological parts of windmill palm were examined and comprehensively characterized after an alkali treatment. Leaf sheathes (LS) with the highest cellulose content (52.26%) achieved the most efficient extraction of fibers. Single fibers extracted from the vascular bundles of the windmill palm raw material had a slender shape with a tapering and sealing terminus, with each single fiber possessing a lumen in its cross-section. These windmill palm fibers displayed similar chemical compositions, but they exhibited significant differences in morphological parameters. Leaf blade fibers (LBFs) had the longest length (1240 μm ± 470 μm) and highest aspect ratio (121.39), which presented excellent potential as a reinforced fiber. After the alkali treatment, almost all of the hemicelluloses and lignin were removed, which resulted in increased crystallinity of extracted fibers. Thermogravimetric analysis confirmed LS stability up to 319 °C, which was higher than that of other materials from windmill palm.
Windmill palm single fibers (WPSFs) and fiber bundles (WPFBs) were extracted from a windmill sheath mesh. For the palm fiber acoustic application, WPSFs/WPFBs nonwoven materials and windmill palm fiber (WPF)/polyvinyl alcohol (PVA) coated nonwoven mats were developed. The effects of conditions such as the thickness and surface density of the materials and the concentration of PVA were studied. The sound absorption coefficients of all of the samples were measured using an impedance tube instrument. The statistical significance of the differences between these materials was tested using Duncan's grouping method. Based on the results, the windmill palm fiber can be regarded as appropriate for use as a sound absorbing material. The addition of PVA was an effective way to improve the acoustic properties of the WPF/PVA coated nonwoven mats. This coated mat exhibited a greater ability to absorb sound than WPSFs/WPFBs nonwoven materials. The acoustic properties of the materials exhibited good results, with an average sound absorption coefficient of 0.38 when the concentration of PVA was 1 wt.%.
In this work, windmill palm fiber (WPF), alkali-treated fiber (AF) without hemicellulose and bleached fiber (BF) without lignin were prepared and buried in soil for 30, 60 and 90 days. The surface morphology, chemical composition, crystallinity degree, mechanical properties, and residual mass rate of the samples, before and after biodegradation, were investigated. According to the results, soil burial degradation can remove the parenchyma cells and silica-bodies of WPF and deplete droplets containing the lignin of alkali-treated fiber after it has been buried for 30 days (AF30), and degradation of the single fiber cell wall of bleached fiber after it has been buried for 30 days (BF30). Buried in natural soil, lignin has a slower degradation rate than that of hemicellulose. WPF showed no significant differences in tensile strength after burial in soil for 90 days, because of the integrity fiber structure decreased the biodegradation. The most serious decrease, about 43%, in tensile strength occurred in AF after it had been buried for 90 days (BF90). This basic knowledge may be helpful for windmill palm fiber applications, especially for biodegradable composites.
Three types of wet-laid nonwoven materials with windmill palm fibril (WPF L ), WPF L /windmill palm fiber bundles (WPFB) and windmill palm fiber (WPF)/polyvinyl alcohol (PVA), were prepared. The morphology and length distribution of WPF L and WPFB were analyzed by digital microscopy and image processing software. The filtration efficiency, air permeability and sound absorption properties of 12 samples of wet-laid nonwoven materials were tested. Adding PVA improved the porosity and enhanced the filtration efficiency, air permeability and acoustic properties of the nonwovens.
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