Evaluation of fiber wettability based on an immerging force measurement

This article provides a new approach to estimate the wettabilitv of fibers based on the force analysis in immerging procedure. A fiber in horizontal is forced into and withdrawn from the liquid at a certain speed, and the force changes are detected simultaneously. The experimental results show that the force impulse can be found at fiber contacting with liquid and immersed into liquid, and its value depends on the wettability of the fiber. According to the force impulses of different fibers, the immerging behavior of the fibers can be obtained and categorized into four characteristics. Meanwhile, the wettability of the fibers can be evaluated with the wettability factor, w, derived from the fiber immerging curve, where w is the ratio of the force increment on fiber initially contacting with the liquid to the force increment on liquid Surface closing with fiber immerging into the liquid, and with the contact angle, theta, calculated from the wettability factor (theta = pi/(w+1)) supposed that the fiber is a circular cross section. The pulling-out test for a fiber has also been conducted and the results are discussed briefly in this article. The force measurement indicates that the method can be used for various fibers with short length, or lower density than that of the liquid, or poor wettability. (c) 2006 Wiley Periodicals, Inc.