Effect of 5% Alkali Treatment on Ramie Fiber for Composite Application

Ramie fibers are biodegradable, lightweight, and hydrophilic. When ramie fibers are combined with a hydrophobic polymer matrix, the interfacial bond is poor due to differences in compatibility between the ramie fibers and polymer matrix. Alkali treatment is one famous method to enhance adhesion bonding between the hydrophobic polymer matrix and natural fibers. In this work, the effects of alkali treatment on the characteristics of ramie fibers were examined. The ramie fibers were alkali-treated using 5% NaOH solution for 2 h. The untreated and alkali-treated ramie fibers were characterized through the diameter measurement, tensile test, FT-IR, XRD, and FE-SEM. Results demonstrated, ramie fiber treated with 5% alkali saw 21.7% in diameter. In addition, after being treated with 5% alkali, ramie fibers tensile strength improved by 54.89%. The crystallinity index rose by 7.5% in response to the alkali treatments as well. This showed that the hemicellulose, wax, lignin and impurities in the ramie fibers were eliminated by the 5% alkali treatment. The use 5% alkali-treated ramie has great potential as an alternative reinforcing material for polymer composites.