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Heats of dyeing of Chrysophenine G, Cl!lorazol Sky Blue I T , and Congo Red 011 cotton, viscose, and cul)raiiiiiioiiiiiiii rayon have been deterniinetl. It is shown that, except for the initial low concentration of adsorbed dye, the values of heat of dyeing remain more or less the same over a fairly wide range of concentration of adsorbed tlye, and that beyond a critical dye concentration, the values tend to decrease continuously lvlien the proportion of the adsorbed dye is increased. Values for the critical concentration of adsorbed dye beyond which the values of heat of dyeing tend to decrease agree closely with values for (lye adsorption at which niasiniuin voluine contraction in the substrate takes place, as observed from density ineasurenients, and also with values of dye concentrations where masiniuni estent of oxidation of cellulose takes place during catalytic oxitlation of the fiber substance by sodium hypochlorite iii presence of the dye. X ne\v tlierniodynaniic approach has been developed to express the activity of the dye in a cellulosic fiber substance in terms of the fraction of the total sites occupied at a particiilaistage of dyeing. Based on this thermodynaniic approach, affinity values of the three direct dyes for the three cellulosic fibers under different experiniental conditions Iiave I,een tletermineti ; the validity of the treatment is discussed.

SynopsisThermal analysis of cotton samples grafted with acrylamide, acrylonitrile, methyl acrylate, and methyl methacrylate individually and in mixture compositions has been carried out. Additional endothermic peaks in the DTA curves characteristic of the polymers grafted were observed. Graft copolymerization of acrylamide and acrylonitrile makes cotton thermally more stable, while in the case of methyl acrylate-and methyl methacrylate-grafted cottons, the initial decomposition starts a t higher temperatures, but subsequent decomposition is faster and the overall thermal stability is lowered. In the case of binary mixtures of acrylamide and acrylonitrile, inception of decomposition starts earlier, but subsequent decomposition takes place a t much higher temperatures than for individual monomer-grafted cottons. Interaction between monomers during grafting is indicated. When fabric samples containing polyacrylamide grafts are methylolated and subsequently crosslinked, there is a reduction in the thermal stability of the treated cotton.

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