Preparation Of DMC-Modified Cationic Cotton Fabrics And Its Application In Salt-Free Dyeing Of Reactive Dyes

The traditional dyeing process, especially the exhaust dyeing process causes serious environmental pollution, which has been one of the most pressing environmental issues to be solved for years. To solve this problem, novel cationic cotton fibers were prepared through the graft polymerization with Methacryloxyethyltrimethyl ammonium chloride (DMC) and potassium persulfate-sodium hydrogen sulfite as the cationic monomer and the redox initiation system, respectively. In our study, the DMC-modifiedcotton fabricsavoid salt and color contaminationofreactive dyeing, and the utilization of reactive dyes was improved.Based on the content of cations onto the cotton and the fixationof Reactive Blue KN-R, the grafting conditions were then determined:mole ratio of reductant to oxidant was 0.4:1, mole molar ratio of initiator to monomer was 1:100, DMC concentration was 50g/L, and the reaction temperature and time were 30℃ and 60 min, respectively. Moreover, the reaction was carried out under the protection of nitrogen. The content of cations onto the cotton was 0.0843 mmol g-1. ATR-IR was used to confirm the synthesis of graft copolymer. XRD, SEM and TGA, DSC, strength testing and other methods were used to analyse its physical and thermal stability properties.Under the above conditions, fixations of Reactive Blue KN-R, Reactive Red M-3BE and Reactive Yellow M-3RE on themodified cottonreached96.8%,97.3%and 98.7%,29.6%,18.1% and 22.2% higher than that obtained from the traditional dyeing, respectively. The K/Sand fastness properties increased as compared to those untreated cotton fibers. To reach the K/S value of the modified cotton, the dye concentration of Reactive Blue KN-R, Reactive Red M-3BE and Reactive Yellow M-3RE was 15.6%,40%and 20% higher and the colorimetric properties were comparable with the modified cotton. The colorimetric properties of the DMC-modified cotton were the same as the untreated cotton.The adsorption processes of three reactive dyes Reactive Blue KN-R, Reactive Yellow M-3RE and Reactive Red K-2BP onto the DMC-modified cotton fabrics werestudied under 30℃ and 50℃. Resultsshowed that the adsorptionisothermal curves were all fitted to the Langmuir model, and the adsorption reaction was an endothermic one. Maximum adsorption amounts of Reactive Blue KN-R, Reactive Yellow M-3RE and Reactive Red K-2BPwere29.15 mg g-1 and 30.40 mg g-1,24.15mg g-1 and 33.67 mg g-1,24.10mg g-1 and 29.33 mg g-1, respectivelyunder 30℃ and 50℃. These maximum adsorption amountsof reactive dyes were all higher than thetheoretical values, which indicated that covalent reaction happened between the cotton and the dyes.