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Title: Reactive dyes for cellulose : selectivities in alcohol/water solutions
Author: Ratcliff, J.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1995
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This project is concerned with reactive dyes for dyeing cellulose (cotton) where reactive groups in the dye molecule form a covalent bond with hydroxyl groups in the cellulose chain by nucleophilic substitution or addition mechanisms. A fundamental problem is that the undesirable hydrolysis of the dye is a competing reaction under dyeing conditions and the hydrolysed dye is then no longer available for reaction with the fibre. The particular feature of interest is the chemical selectivity of the reactions of these dyes towards the fibre in preference to reaction with water and the factors which can influence these selectivities. In order to study the selectivities alone, without complications from the diffusion characteristics and substantivities of individual dyes, a homogeneous system was preferable for the investigations. So, a range of compounds were chosen as models to represent cellulose in these reactions. They covered simple alcohols, diols, polyols, and carbohydrate and sugar molecules - methanol, n-propanol, isopropanol, ethane-1,2-diol, α- and β-methylglucopyranoside, tetrahydropyran-2-methanol, mannitol, sorbitol, glucose and maltose. Using methanol as a cellulose model, the effects on rates and selectivities of varying the temperature between 0 and 60°C and additives to the dye bath such as acetonitrile, tetrabutylammonium bromide, urea, sodium chloride, sodium carbonate and dimethylformamide in a concentration of 100g/l have been investigated. Finally a survey of dyes with a wide range of reactive systems was carried out to determine whether selectivities are related to the reactive group that is used in the dyeing process. Reactive groups covered were : dichlorotriazine, monochlorotriazine, monofluorotriazine, chlorodifluoropyrimidine, dichloroquinoxaline, masked vinyl sulphones and acrylamides.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available