The recycling and the ultrasonic treatment of bamboo fibers are investigated. And the bamboo paper density, the tensile strength and other properties of the handsheets are determined. Repeated recycling leads to a decrease of the paper density and the tensile strength. The Page equation(1/T=1/F+1/B) is used to evaluate the strength contributions of a single fiber and the inter-fiber bond to the tensile strength of the bamboo handsheet. It is found that the bamboo paper strength improves as a result of the ultrasonic treatment, which is essentially due to the enhanced inter-fiber bonding strength and the slight changes of the zero-span tensile strength. Optical microscopic observations indicate that, the ultrasonic treatment has induced the fiber cutting, the fiber swelling, and the fibrillation, which contributes to the bamboo paper strength improvement. The WRV(Water retention value) depends upon the times that the fibers are recycled, and the repeated recycling leads to a reduction of the bamboo pulp WRV. Interestingly, the ultrasonic treatment significantly enhances the water retention, as well consistent with the results related to the bamboo paper strength.

bamboo fiber  /  recycling  /  ultrasonic treatment  /  inter-fiber bonding strength