phenomena occurring at a solid-liquid interface, such as The effect of tannic acid and/or Rhodamine B on the surface wettability, particle aggregation, flotation, dyeing, etc., defree energy components of bleached cotton was studied. The zeta pend to a large extent on the kind and magnitude of the potential of cotton fabric was also measured in 10 06 -10 02 M tansurface and interfacial free energies involved. The surface nic acid solutions and in the presence of 10 03 M NaCl. It was free energy concept can also be used for investigations of found that the zeta potential of cotton is negative and that its the physico-chemical properties of textile fabric surface and absolute value decreases with increasing concentration of tannic the results of such investigations can be correlated with imacid. In the presence of NaCl the potential is more negative than portant technical properties of textiles (1, 2). However, there in the tannic acid solutions alone. One may conclude that both are many complications because of changes taking place in H / and Cl 0 are potential-determining ions for the cotton surface.
The surface is practically monopolar Lewis basic with an electron the structure and composition of the surface layer of the donor, g 0 S , interaction of 50.1 mJ/m 2 , while its electron acceptor fabrics (3-5). Nevertheless, the analysis of the results of interaction, g / S , equals only 0.92 mJ/m 2 . This polar character of surface free energy components, i.e., the textile, the surfacthe surface results from the presence of carboxyl end-groups. The tant, and the dye adsorption on it, and changes of the zeta apolar Lifshitz-van der Waals interaction, g LW S , amounts 45.0 potential, provides an extensive information about the sys-mJ/m 2 . The cotton surface with adsorbed tannic acid from 10 03 tem, which can be useful for dyeing and finishing processes or 10 02 M solutions, or Rhodamine B from 10 03 M solutions, as of textile fabrics (3-11). well the surface dyed with Rhodamine after adsorption of tannic Cotton fibers are used preferentially in the textile industry. acid, shows different values of the surface free energy components. These fibers are markedly hydrophilic (11-16), and, it The changes are within ca. 14 mJ/m 2 for apolar g LW S component seems to us, investigation of their dyeing properties for difand within ca. 13 mJ/m 2 for polar g 0 S component. It is believed they result from the presence of the above mentioned polar end-ferent industrial applications is very interesting. The use groups of bleached cotton, phenolic hydroxy groups in the tannic of surfactants to assist wetting of textile fabrics and more acid molecule, and two amine groups and one carboxyl group in particularly for the level of dyeing has become widespread. the Rhodamine B molecule. The adsorption processes occurring in Ionic surface active agents have been used as dyeing assisthe systems are due to both electrostatic interaction and hydrogen tants of cotton, wool, polyamide, and polyester fibers (9bonding between the polar groups. It appeared that the thin-layer 12, 14). Although the electrokinetic properties of cellulose wicking technique adapted to the fabric materials is very useful fibers have been extensively studied, investigations of the for the surface free energy study, especially because the contact surface free energy changes in the dyeing processes of textile angle method cannot be applied for such materials. ᭧ 1998 Academic fibers are rather rare. This also deals with cotton, and practi-Press cally no work has been reported on the surface free energy