WETTING BEHAVIORS OF ASSEMBLIES OF VARIOUS FIBERS

(II) CAPILLARY-TYPE PENETRATION (2)

Abstract

Dependencies of types of fibers and structures of the fiber assemblies on the transport mechanisms of water have been under investigation. In this paper, the comparative measurements were made on the process of horizontal transport of distilled water in the various assemblies which were made from several kinds of fibers and the results obtained are discussed.
Preparation of experimental materials is described in the previous paper. The required quantity of sample fiber was uniformly stuffed into an Acrilan tube of 0.9cm in diameter and 10cm in length, thus the column of fiber assembly was made. The degrees of porosity (degrees of opening) of the assemblies were 65, 75, 85 and 90% respectively. The Acrilan tube was kept horizontally and the end of the tube was brought to contact with distilled water. The rate of water transport through the assembly was measured by eye-observation and an electrical contacting device. The travel of water front as a function of time has been followed for each kind of fiber and degree of porosity.
The water transport curve varies greatly with the kind of fiber in the case of same degree of porosity. The assemblies of acrylics which belong to synthetic fiber were penetrated extremely rapidly at all ranges of porosity examined. It was described in the previous paper that in the vertical capillary penetration of water through the assemblies of acrylics, acetate, vinylon, absorbent cotton and rayon the increase in openness (porosity) of the assemblies give rise to the decrease in the penetrating quantity. In contrast to this, the rate of horizontal water transport has a linear relationship with the porosity, and, in general, the greater the diameter of capillaries the larger the rate of wicking. In the compact rayon assemblies of small porosity, the wicking rate was greatly reduced owing to the possible clogging of capillary spaces by the swelling of fibers. The square of the travelled distance (S_h) of water front was plotted against time (T_h) for each degree of porosity of rayon assembly. From the linearity of this relationship equation, S_h²=K^c•T_h was obtained in the wide variety of porosity of assemblies made from sufficiently wettable fibers.