Photofading mechanisms of dyes in solution and polymer media

A Study on Coloring Properties ofRheum emodion Jute Union Fabrics

“…Thus, it is evident that the complex mixture of anthraquinone structures of Rheum emodi is capable of forming stable complexes with the metal ions, resulting in improved colourfastness to washing, rubbing, and lightfastness. Besides, presence of anthraquinone structure as is found in Rheum emodi shows in general an increased resistance to light fading [11]. Moreover, albumin being a heat-coagulating protein acts as fixing agent and, hence, further enhances the fastness properties of jute union fabrics.…”

Modification of cotton fabric with acrylamide in the presence of K2S2O8for improving dyeability of natural dyes

“…Higher dye content of the fibre results in higher light fastness rating of the substrate in view of the fact that photofading of dye in any polymer media is a surface phenomena and with an increase in dye content, the surface area per unit volume of the assemblage of the dye molecule decreases with a consequent decrease in the fading rate of the dye incorporated in the polymer media (Allen, 1987). Application of ferrous sulphate following a pre-mordanting method increased the light fastness rating of the acrylamide-modified cotton fabric dyed with Camellia sinensis and Punica granatum further.…”

“…Such high light fastness rating of acrylamidemodified cotton dyed in the presence of ferrous sulphate following a pre-mordanting method with Camellia sinensis and Punica granatum is the consequence of (i) association of two or more dye molecules, and (ii) polymerisation of the dye molecules affected in the presence of ferrous sulphate (Oakes, 2001;Oakes & Dixon, 2004). Iron with its good complex-forming ability (Lee, 1996) can hold two or more suitable dye molecules together to form an insoluble large complex which enhanced the light fastness of the dyed substrate (Allen, 1987;Gupta, 1992). Such complexation of the coloured component within the fibre structure leads to polymerisation of the dye molecules, which was also responsible for improvements in light fastness of the dyed substrates (Allen, 1987;Oakes, 2001;Oakes & Dixon, 2004).…”

“…Iron with its good complex-forming ability (Lee, 1996) can hold two or more suitable dye molecules together to form an insoluble large complex which enhanced the light fastness of the dyed substrate (Allen, 1987;Gupta, 1992). Such complexation of the coloured component within the fibre structure leads to polymerisation of the dye molecules, which was also responsible for improvements in light fastness of the dyed substrates (Allen, 1987;Oakes, 2001;Oakes & Dixon, 2004). Such effects became more pronounced in acrylamide-modified cotton owing to the presence of more number of dye molecules in it than in the unmodified cotton in a manner that ultimately produced an enhanced light fastness rating for acrylamide-modified cotton when dyed with the above-mentioned dyes in the presence of ferrous sulphate following a pre-mordanting method.…”

Assessment of fastness of dyeings

“…Light fastness, a crucial property of dyed textiles, is governed by (i) wavelength of incident radiation, (ii) compactness of dye and fibre structures, (iii) dye-fibre system (Oakes, 2001;Allen, 1987;Bentley et al, 1974), (iv) degree of dye aggregation , (v) effective humidity (combination of air, surface temperature and relative humidity governing the moisture content on the surface of fibre), (vi) dye induced catalytic action, (vii) temperature, (viii) availability of oxygen (photo-oxidation) or UV light (photo-reduction), (ix) amount of colourant on fibre, i.e. Light fastness, a crucial property of dyed textiles, is governed by (i) wavelength of incident radiation, (ii) compactness of dye and fibre structures, (iii) dye-fibre system (Oakes, 2001;Allen, 1987;Bentley et al, 1974), (iv) degree of dye aggregation , (v) effective humidity (combination of air, surface temperature and relative humidity governing the moisture content on the surface of fibre), (vi) dye induced catalytic action, (vii) temperature, (viii) availability of oxygen (photo-oxidation) or UV light (photo-reduction), (ix) amount of colourant on fibre, i.e.…”