An isoreactive dyeing system is a system in which the sorp tion m e is kept constant throughout the whole kinetic period. A theoretical study of this condition was carried out using the modified kinetic equation o f Cegama-Fiiente and the Arrhenius equation. The isoreactivity equation is used to determine the conditions of temperature-time which should be applied during dyeing to achieve constant sorption at different sorption times. Finally, the theoretical values and those found experimentally in the dyeing systems: wool-acid dyes, viscose rayon-direct dyes and acrylic fibres-cationic dyes are compared.
343theory is further substantiated by the work of Vail et al. l12 J who show that dimethylolacetamide finishes are not very stable to strong acid hydrolysis. This is.attributed to the electmn-donating characteristic of the methyl group.Schwenker and Pacsu [ 10 J reported that cotton could be made flame resistant by first preparing tnesyl or tosyl cellulose and then replacing the tosyl or mesyl groups with halogens. Bromine and iodine were very effective in producing flame resistance. The methylol derivative of DBCA seemed to offer an attractive and simple way of adding bromine to cotton hecause of its water solubility, and hecause conventional padding and curing techniques could he employed. Unfortunately, however, the sensitivity of the finish to relatively low temperatures removes it from the realm of a practical finish for cotton apparel goods. Fabrics with these properties may find favor in other end uses than for apparel. This work does support the theory discussed bey Schwenkcrand Pacsu r 101. The theory stages that the chemical modification of cellulose reduces the levoglucosan forming potential of cellulose and that bromine or iodine acts chemically on the flaming gases to impart flame resistance. The low decomposition point of the DHCA-treated cotton probably is a contributing factor to flame resistance.
The diffusion equation of Crank for a finite dyebath is not adequate to apply either to dyeing with high exhaustion or to annulary dyeing. It is for this reason that a systematic study of the existent empirical kinetic equations has been made. The authors also propose other new equations, based on the equation of Cegarra-Puente, which can be used to replace Crank's equation.
The individual and combined influence on the bleaching of wool of the concentration of hydrogen peroxide, temperature and time of treatment have been studied, using a rotatable central design of experiments in which the values of the above variables covered the values used in industry. Mathematical treatment of the values of the optical, chemical and mechanical parameters has enabled equations to be derived, from which the value of any parameter can be computed when the values of the variables are within the range of the plan of experiments, resulting in a good agreement being obtained between experimental and calculated values. Use of these equations facilitates optimization of the process of wool bleaching, and bleaching conditions leading to the whitest wool have been suggested for an allowable chemical degradation (alkali solubilities of 25%and 30%). More severe conditions of bleaching do not necessarily produce a whiter wool, but cause greater chemical and mechanical degradation of the fibre. An excellent linear correlation has been found between the chemical parameters modified by the bleaching operation and between these and the wet tensile strength of the fibre.
A dyeing method consisting of discrete additions of dye to the dyeing solution, rather than the usual practice of adding it all at the beginning, has been studied in order to assess, through a theoretical model, the precise additions required to get the same dye absorption in each constant interval of time, as well as the amount of dye to be absorbed by the fiber at each temperature so as to reach a certain level of exhaustion.
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