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Abstract
The dyeing performances of two reactive dyes (I and III) containing new bifunctional disulphide bis(ethylsulphone/ sulphatoethylsulphone) DSB(ES-SES) and disulphide bis(ethylsulphone-monochlorotriazine)DSB(ES-MCT) reactive systems respectively are investigated. These dyes provide the bases for implementation of temporarily high molecular dye structures, which under the neutral dyeing stage exhibit high substantivity towards cotton fabric. Further, the counter alkaline dyeing stage for these reactive dyes promote high exhaustion and fixation as a result of the characteristic disulphide bis(ES) ẞ-elimination and the formation of the highly reactive bis(VS) and (VS/MCT) dye molecules, respectively. The dyeing performance of the DSB(ES-SES) and DSB(ES-MCT) dyes are compared with two typical reactive dyes such as Remazol Black B dye II and Remazol Red RB dye IV respectively. Both disulphide dyes I and III showed higher exhaustion and fixation values than typical corresponding reactive dyes II and IV even at low salt concentration.
Within the framework of this approach, the original work presented in the thesis comprises the following studies:
1- The synthesis of a bifunctional DSB(ES-SES) reactive dye I, containing a disulphide bis(ethylsulphone) and sulphatoethylsulphone reactive groups, by a twice- coupling of H-acid with the diazotised p- aminophenylsulphatoethylsulphone component and the bis-diazotised disuphide bis(ethylsulphonediamine) intermediate.
2- The synthesis of a bifunctional DSB(ES-MCT) reactive dye III, containing a disulphide bis(ethylsulphone) and monochlorotriazine reactive groups, by coupling a condensation product of cyanuric chloride with H- acid/sulphanilic acid- with the bis-diazo salt solution of disulphide bis(ethylsulphonediamine) intermediate.
3- Studying the dyeing behavior of the synthesized bifunctional dyes I and III compared with commercial dyes such as Remazol Black B dye II and Remazol Red RB dye IV, respectively. The factors affecting the dye ability on cotton fabric at different salt, alkali and dye concentrations, dyeing temperature conditions, dyeing time, and liquor ratios are studied.
4- Studying the fastness properties of the investigated disulphide reactive dyes I and III, and their comparable dyes II and IV on cotton fabric. The fastness to rubbing, washing, perspiration, and light, are evaluated.
The results obtained are summarized as follows:
- In chapter two, dyeing of cotton with the disazo bifunctional DSB(ES-SES) reactive dye I, in which the characteristic disulphide bis(ethylsulphone) DSBES and sulphatoethyl-sulphone SES B-elimination reactions during the alkaline fixation of dyes lead to the formation of bifunctional bis(VS) reactive system, offering higher fixation efficiency when compared with a typical bifunctional bis(VS) dye (Remazol Black B). The temporary high molecular structure of the disazo DSB(ES-SES) dye results in good substantivity on cotton (increasing the primary exhaustion) at a variety of salt concentration. On the other hand, the primary exhaustion results for both (the synthesized dye and the commercial one), applied at different neutral dyeing temperature, indicate that the dye substantivity increases as the temperature increases from 40 to 60°C. The exhaustion values obtained for the DSB(ES-SES) dye, are approximately 25% higher compared to Bis(SES) dye (Remazol Black B), when applied at the same dyeing conditions.
As a result of high primary exhaustion obtained at the neutral dyeing stage of dye I, there is a pronounced increase in the dye exhaustion and fixation values even at a short dyeing time, resulting in a remarkable dye fixation efficiency along the range of fixation time (45 min). On increasing the dyeing time, the exhaustion and fixation values of DSB(ES-SES) reactive dye approach the optimum value and are higher than those of the Bis(SES) Remazol Black B. This result enables the disulphide dye I to be applied at approximately 15 min shorter dyeing time than Remazol Black B. The performance of DSB(ES-SES) reactive dye, the neutral exhaustion and alkaline fixation behavior, is a function of the dyeing efficiency of such type of reactive dyes. The optimum exhaustion and fixation values of the disazo DSB(ES-SES) reactive dye were achieved by exhaust dyeing at 60 g/l sodium sulphate and 40 °C (exhaustion stage), and at 25 g/l sodium carbonate and 60 °C (fixation stage), as a result of high degree of conversion of the dye, since a number of disazo reactive products may result both SES and DSB(ES) B-elimination of the dye.
- In chapter 3, the dyeing performance of a bifunctional DSB(ES-MCT) reactive dye III was investigated on cotton, the presence of the disulphide bis(ethylsulphone) DSB(ES) group, which can ẞ-eliminates during the alkaline fixation stage of dyeing to form heterobifunctional VS/MCT reactive system, offers higher fixation efficiency when compared with the typical bifunctional MCT/SES dyes such as Remazol Red RB. This dye behaves in some cases like the disazo DSB(ES-SES) reactive dye I as the presence of DSBES group makes the dye has a high molecular structure. The results showed a good substantivity of the dye on cotton at the neutral dyeing stage. The extent of the primary exhaustion as well the dye- fiber fixation is pronounced even at low salt concentration and at short fixation time, resulting in a remarkable dye fixation efficiency under all the dyeing conditions studied. The optimum exhaustion and fixation values of the DSB(ES-MCT) reactive dye were achieved by exhaust dyeing at 60 g/l sodium sulphate and 40 °C (exhaustion stage), and at 25 g/l sodium carbonate and 60 °C (fixation stage).