Dye-fibre combination

Heane has suggested that, for a given dye-fibre combination, the important factors influencing the degree of levelness in package dyeing include ... 

An interesting aspect of sorption is the effect of the rate constant of sorption k=k /kl) on the dyeing process. As mentioned before, k and k2 are the adsorption and desorption rate constants, respectively. Thus, k (kl/kl) is the actual adsorption coefficient, which characterises the adsorption properties for different dye/fibre combinations. 

Dyeing of different dye/fibre combinations can be represented by a number of adsorption isotherms. The analysis of the simnlations based on various adsorption isotherms demonstrates distinct rates of dye uptake and levelness of dye distribntion in the package dnring the initial stage of dyeing for varions adsorption profiles ... 

Since simrrlatiorrs based on the Nemst adsorption isotherm prodnce the poorest levelness resrrlts, a worst case scenario control strategy based on the Nemst adsorption isotherm cotrld be nsed to control the dyeing of any dye/ fibre combination. This wotrld resrrlt in a simplified modelling and control methodology, since the Nemst isotherm represents a linear relatiortship between control and measrrrement parameters. 

In the case of quaternary derivatives made from the non-planar aliphatic amines 7.64, 7.65 and 7.66, steric strains further destabilise the C-N+ bond so that reaction with cellulose occurs under alkaline conditions at 30 °C, whereas temperatures of about 40-50 °C are required for the pyridinium derivatives 7.67. The quaternisation approach appeared to offer the opportunity to prepare dyes yielding reactivity levels intermediate between those of aminochloro- and dichlorotriazine dyes without loss of the desirable stability of the dye-fibre bond to acidic conditions that is characteristic of aminohalotriazine dyes. Unfortunately, this ideal was not attainable because of the objectionable odours of the tertiary amines liberated by the fixation reaction and the sensitivity of the reactivity behaviour of the quaternised derivatives to the nature of the chromogen attached to the triazine ring, making it difficult to select compatible combinations of dyes. 

Another point in this connection is that the amidoazines dye fibres the colour of the monoacid, and not of the polyacid salts, thus showing that the azine group effects the combination with the fibre. 

Carbamates. A fast, sensitive and selective method for the concentration and analysis of 9 N-methylcarbamate pesticides was reported by Volmer et al. [507]. Three different SPME fibres combined with short-column ESI-LC-MS(-i-) and MS/MS were applied. The detection limits observed were 0.3-1.9 pg Signal intensities increasing by a factor of 2-7 were observed [508] using non-volatile buffers in the separation process prior to ESI-MS. After EC removal of the non-volatile buffers was essential. The results obtained by ESI and APCI-LC-MS and MS/MS for the analysis of the eight N-methylcarbamate pesticides and their degradation products were compared with results obtain with the application of TSP or PBI (cf. 15.3.3.1 TSP, carbamates) [108]. ESI-LC-MS and TSP-LC-MS were used for quantitative determination of 10 different carbamate pesticides which showed a broad variety in polarity. ESI-SIM detection limits were typically 10-60 pg which was 10-150 times better than using TSP-MS (cf. 15.3.3.1 TSP, carbamates) [509]. Interfacing a commercial ESI source to an ITMS allowed the determination of carbamates as well as triazines and azo dyes. Identification could be performed either by IT-MS/MS or by ESI-CID [424]. 

Mordant acid dyes combine simultaneously with the mordanting agent (generally Cr(OH)j) and the fibre the dyestuff generally contains ortho OH -azo or OH-OH groups. 

The NO-group is the most active colour-producing (chromophoric) group known. With a radical such as isobutyl which is of no account for the absorption of light, it produces a blue nitrosohydrocarbon. In spite of their intense coloration the nitroso-compounds are not dyes, since they lack the auxochromic groups (e.g. NH2 or OH) necessary for combination with textile fibres. 

It is otherwise with cotton, which is almost chemically pure cellulose, and hence is chemically indifferent in a tinctorial sense. Here combination with the dye results from the use of mordants which are adsorbed colloidally on the fibre before dyeing. The mordant can then enter into chemical union with the dye as a complex compound. For an important group of acid dyes (p. 335) the mordants are chiefly metallic hydroxides, namely, those of chromium, aluminium, iron, antimony, tin, etc., whilst for basic dyes tannin is the usual mordant. 

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