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Investigation of interactions between guar gums, reactive dyes and surfactants

其他書名	Raziskava medsebojnih vplivov guara gostil, reaktivnih barvil in površinsko aktivnih snovi : dissertation
出版	V. Kokol, 2001
URL	http://books.google.com.hk/books?id=wQ9ZOwAACAAJ&hl=&source=gbs_api

註釋Printing of cellulose fibers with bifunctional bireactive dyes and nonsubstituted polysaccharide guar gum thickeners causes extremely high fabric handle and changes in the depth of color, which is ascribed to the covalent binding of guar gum macromolecules on the cellulose via bireactive dye. The use of various nonionic surfactants to reduce the mentioned undesired interactions and to improve the fabric handle of prints made with bireactive dyes is presented in the dissertation. The action and the efficiency of the selected surfactants were studied using tensiometry, rheology, UV/VIS spectroscopy and Size Exclusion Chromatography (SEC). It can be concluded from the obtained results that nonionic surfactants prevent the occurrence of undesired interactions between the reactive dye and the guargum thickener due to the physical interactions (H- bonds, van der Waals forces) and chemical covalent bonds between the surfactant and the guar gum thickener and between the surfactant and the reactive dye. It should be noted that the interactions between the surfactant and guar gum are predominant. The efficacy of nonionic surfactants decreases in direct proportion with the diminishing hydrophilic character of the molecule (C18EO20 > C18EO10 > C18EO4)and with the growing length of the hydrocarbon chain (C16EO10 > C18EO10). The influence of the degree of etoxylation is greater than the influence of the hydrocarbon chain length. The efficiency of the surfactant also increases with the increasing concentration of the surfactant and with the increasing substitution degree of guar gum. Prints made with a printing paste that contains a nonionic surfactant have a much softer fabric handle, a lower extent of dye penetration and a slightly lower depth of color than prints made with a printing paste without a surfactant. The observed changes are a consequence of reduced interactions between the reactive dye and the guar gum (fabric handle) and the occurrence of interactions between the surfactant and the guar gum (dye penetration) as well as between the surfactant and the reactive dye (color shade). The best prints or the weakest cross-linking of guar gum macromolecules via the bireactive dye is obtained with the printing paste that contains the C18EO10 surfactant and a highly carboxymethylised (DS = 1.1) guar gum thickener. SEC used together with RI- and UV/VIS- detectors has proved to be a successful alternative method for monitoring the occurrence of the reaction product between the reactive dye and the polysaccharide thickener as well as interaction products or complex formations after the addition of surfactant into the printing paste.