Measurement of Capillary Wetting Rate in Fibrous Assemblies

• Published in: Journal of Home Economics of Japan Vol. 52; no. 9; pp. 849 - 854
• Main Authors: TAGAWA, Mieko, GOTOH, Keiko
• Format: Journal Article
• Language: English; Japanese
• Published: The Japan Society of Home Economics 2001; 一般社団法人 日本家政学会
• Subjects: capillary wetting; contact angle; fibrous assembly; liquid viscosity; surface free energy; water/ethanol mixture; 接触角; 水/エタノール混合液; 浸透ぬれ; 液体粘度; 繊維集合体; 表面自由エネルギー
• ISSN: 0913-5227; 1882-0352
• DOI: 10.11428/jhej1987.52.849

The capillary wetting rates of water/ethanol mixtures into fibrous assemblies were determined from the changes in weight due to wetting. Silica filters untreated and silanized with three silane coupling agents, γ-aminopropyltriethoxysilane (APTES), methyltriethoxysilane (MTES) and perfluoroethyltri-methoxysilane (FETMS), were used as fibrous assemblies. The advancing contact angles on a silica single fiber and the surface free energies for water/ethanol mixtures were measured by the Wilhelmy and the pendant drop techniques, respectively. A strip of the silica filter was suspended from the arm of the electrobalance and the weight was automatically recorded during the contact of the lower edge of the strip with water/ethanol mixtures. The weight of water/ethanol mixtures penetrated into the silica filter increased with time and showed saturation. The weight was converted into volume using the density of water/ethanol mixtures, and was used as a measure of the capillary wetting rate. The rates were found to depend on the contact angle, the surface free energy and the viscosity of water/ethanol mixtures. By comparing the results of the untreated filter with those of the silanized filters, it was shown that the viscosity of water/ethanol mixtures in the vicinity of the fiber surface was associated with the capillary wetting rate.