Investigation of the hydrophobic and acoustic properties of bio windmill palm materials

Windmill palm fibers are an abundant lignin-cellulose fiber resource. Single palm fibers can be prepared using an alkali treatment method. However, these fibers have hydrophilic surfaces, and following drying the fibers exhibit serious aggregation. This limits their application as acoustic materials. In this work, both alkali and acetylation treatments were used to modify the characteristics of windmill palm fibers. These treatments caused the surface of the fibers to become hydrophobic and increased the specific area and free vacuum space of the fibers, thus lowering energy loss. Scanning electron microscope observations combined with Fourier-transform infrared spectroscopy showed that the acetylation treatment resulted in the substitution of hydroxyl groups with acetyl groups, and the formation of nanoscale pores (10~50 nm). The results of the moisture-absorption and contact-angle tests showed that the moisture regain value decreased to 3.86%, and the contact angle increased to above 140° after acetylation treatment. The average sound absorption coefficients of the alkalized and acetylated nonwoven fabrics were 0.31 and 0.36, respectively. The masses of the acetylated samples were 50% those of the windmill palm sheath samples.