Modification and Characterization of Hemp and Sisal Fibers

This work is to investigate the effectiveness of the surface treatment technique of fiber impregnation in polymer solution in improving compatibility of natural fibers with matrix. Hemp and sisal fibers were treated through polymer coating in comparison to acetylation, alkalization/acetylation, and silanization. Different analytical techniques were employed to examine effect of surface treatment, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) in nitrogen and air. FTIR showed acetylation combined with alkalization led to the highest hemicellulose and lignin removal among all treated fibers for both fibers, while polymer coating led to an increase at peak around 1,736 cm−1 due to the carbonyl group. SEM micrographs of treated fibers showed cleaner surfaces due to removal of waxy substances and lignin during treatments. Thermal stability of treated fibers increased based on TGA results except for the alkalized/acetylated fiber. Acetylated fibers had the lowest moisture content, thus demonstrating that acetylation is an effective technique to reduce the hydrophilic tendency of natural fibers. In comparison, polymer coating was not as effective as other treatment methods.