effect of surface treatment on the physical, chemical, and mechanical properties of palm tree leaf stalk fibers

A new class of leaf stalk fibers of the palm tree were extracted and treated with a 5% NaOH solution for 1 h, 2 h, 6 h, and 12 h. The treated fibers were then characterized by tensile strength testing, chemical analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and solid state NMR. The tensile strength of the fibers was improved with an alkali treatment, and the 6 h treatment resulted in the maximum fiber strength. The maximum cellulose content was present in the 6 h-treated fibers; cellulose content was reduced with a longer treatment (12 h). Similarly, SEM, FTIR, XRD, and NMR confirmed the removal of hemicelluloses from the raw fiber surface and the formation of new hydrogen bonds between the cellulose fibril chains with respect to the duration of the treatment. The 5% alkali treatment also improved the fiber density from 0.85 gm/cc (raw fiber) to 1.05 gm/cc, 1.13 gm/cc, 1.17 gm/cc, and 1.25 gm/cc after the 1 h, 2 h, 6 h, and 12 h treatments, respectively.