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Activation Energies of Light Fading of Non–ionic Disperse Dyes in Hydrophobic Polymers
Author(s) -
GILES CHARLES H.,
HOJIWALA BALVANTRAI J.,
SHAH CHAMPAKLAL D.,
SINCLAIR ROY S.
Publication year - 1974
Publication title -
journal of the society of dyers and colourists
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 0037-9859
DOI - 10.1111/j.1478-4408.1974.tb03182.x
Subject(s) - fading , ionic bonding , diffusion , polymer , substrate (aquarium) , disperse dye , crystallinity , photochemistry , relative humidity , materials science , chemistry , saturation (graph theory) , polymer chemistry , ion , organic chemistry , composite material , thermodynamics , decoding methods , physics , oceanography , mathematics , combinatorics , computer science , polyester , geology , telecommunications
Eight non–ionic (disperse) dyes adsorbed in films of cellulose acetates, nylon and poly(ethylene terephthalate) (PET) have been faded by visible and near–ultraviolet radiation at temperatures in the range 15 to 100°C, and in atmospheres of relative humidities (r. h.) from zero to saturation. Fading is accelerated by rise in temperature, and, at r. h. above 5%, by rise in r. h. Activation energies of fading (Ef) (r. h. > 5%) range between about 3 and 18 kcal/mole, and depend on the nature of the substrate rather than on the structure of the dye. Values rise with increasing crystallinity of the polymer structure, except for PET which gives anomalously low values. The extent of dye–fibre interaction is at a minimum with PET and the rate–controlling step is a purely photochemical one. With the other substrates, the rate of fading is controlled by the dye–substrate interaction. The accelerating action of atmospheric humidity over normal ranges is partly due to its influence on the dye–substrate bonding and partly to its effect in swelling the substrate and thus increasing the diffusion coefficient of oxygen.