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ABSTRACT
Nylon 6 fabric is pretreated with tannic acid and subsequently dyed with a cationic dye, Rhodamine B, from an aqueous dye solution and emulsion phase. The emulsion phase of n-hexadecane is emulsified by isopropyl alcohol and stabilized by Rhodamine B/tannic acid complex. Different factors affecting pretreatment and dyeing process have been studied. Changes of moisture regain, tensile strength, elongation and binding stiffness of the pretreated fabric are investigated.
The FTIR spectra of tannic acid pretreatment of nylon are also examined. The pretreated fabric with 10% owf tannic acid shows a slight increase in the tensile strength and elongation percentage. A higher moisture regain and binding stiffness are observed with increases in the amount of tannic acid. The results also indicate that the pretreatment for cationic dyed nylon 6 fabrics with tannic acid promote a higher dye uptake and cationic dye-based emulsion system with better fastness properties relative to those of the dye solution based system. A further improvement in wet fastness is secured by an aftertreatment of all dyed fabrics with a commercial anionic fluorescent whitening agent, Uvitex® RSB 150%.
Keywords: Nylon 6, Tannic Acid, Rhodamine B, Emulsion System Complex, Dyeing Process
1. Introduction
Nylon 6 is in particular, the most synthetic fibre that is widely used for commercial fabric production. It is a macromolecule and its structural units are interlinked by amide linkage (NHCO) with highly crystalline polymer chains. The most important chemical group in nylon polymer is the amino and carboxylic groups found at the ends of the nylon polymer, which provide the sites for dye molecules.
The presence of terminal groups accords nylon fibres substantivity towards several classes of anionic dye; namely, acid (including metal-complex), mordant, direct, reactive and nonionic reactive disperse dyes. The polar and relatively hydrophobic characteristics of the substrate also serve to impart substantivity towards disperse dyes (Ginns, 1979; Burkinshaw, 1995).
Nylon 6 fibres are not easily dyed with cationic dyes. However, in order to improve their dyeability toward cationic dyes, some anionically modification on these fibres must be done either by chemical treatments with anionic agents (Miiller et al., 1977; Bendak et al., 1987) or physico-chemical surface treatments through low temperature plasma treatment and UV excimer laser irradiation and co-polymerization of acrylic acid as well...