Structure and mechanical properties of windmill palm fiber with different delignification treatments

The removal of lignin from natural cellulose fibers is a crucial step in preparing high-performance materials, such as compressed high-toughness composites. This process can eliminate non-cellulosic impurities, create abundant compressible pores, and expose a greater number of active functional groups. In this study, biomass waste windmill palm fiber was used as the raw material to prepare holocellulose fibers through various chemical treatments. The structure, chemical composition, Fourier transform infrared spectroscopy analysis, X-ray diffraction analysis, thermal properties, and mechanical properties, particularly fatigue performance, were studied. The sodium chlorite treated fiber had the highest crystallinity index (61.3%) and the most complete appearance structure. The sodium sulfite treated fiber had the highest tensile strength (227.34 ± 52.27) MPa. Hydroxide peroxide treatment removed most of the lignin and hemicellulose, increasing the cellulose content to 68.83% ± 0.65%. However, all the chemical treatments decreased the thermal property of the fibers.