Effects of cellulase treatment on tensile properties of ramie fiber

Effects of cellulase treatment on structural and tensile properties of ramie fiber were investigated. The tensile strength of ramie fiber decreased drastically by a cellulase treatment causing a small weight loss of the fiber. Scanning electron microscopic observations showed no significant morphological changes, but confocal laser scanning microscopy of the enzyme-treated samples stained with cellobiose dehydrogenase showed the formation of characteristic nodelike structures at every 30-50 mu m along the fiber axis. Fracture planes of enzyme-treated ramie fiber tends to run vertical to the fiber axis, whereas that of untreated fiber tends to be more irregular and oblique. Prolonged enzyme treatment resulted in spontaneous disintegration of the fiber into short fragments with vertically cut ends. These observations suggest that enzymatic attacks on ramie fiber results in the formation of node-like defects with a periodicity of 30-50 mu m along the fiber, which in turn cause significant deterioration in tensile strength.