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Title: Studies in the light fading of dyes
Author: Johari, Devendra Pratap
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1967
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The work includes the use of a variety of means of detecting aggregatos of dye in fibres and films. These include electron micrography and studies of reaction rate. Mainly this work was directed towards elucidating the causes of the improvement in fastness obtained when some reactive dyes become fixed (i.e. covalently bonded) to cellulose. The effect of other substituents such as glucose and methanol, which are similar to cellulose in reaction with the dye forming other linkages, have been studied. The light fastness of fixed dyeings on both Cellophane film and "gel"-Gellophane (i.e. undried material) was higher than that of the unfixed dyeings. X-ray technique did not show the presence of dye aggregates. But the aggregates were detected with the aid of electron microscopy, in fixed dyeings on cellulose films. Their detection in unfixed dyeings on cellulose was not possible as the dye bleeds out in water, before the film is taken on the grid for electron micrograph. The absence of any dichroic effect in the fixed and unfixed dyed films suggested the presence of aggregates and the absence of orientation of dye molecules. Fading of reactive dyes on different substrates e.g. bleachad cotton, mercerised cotton and viscose rayon showed an increase in light fastness with the porosity of the material, i.e. viscose rayon the most amorphous of these fibres gives the highest light fastness. The general conclusion is that the light fastness of reactive dyes is possibly unaffected by the dye-fibre bonds and is related to its aggregation in the substrate. Among other aspects of light fading which were studied are the effect of roughness of fibre surface, of alternate irradiation and storage in the dark of the dye, of various methods of mounting films for exposure, with or without glass support, of the theoretical aspects of the effect of shade depth on fading rate, and of the influence of moisture diffusion rate in the substrate.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available