Synthesis And Dyeing Properties Of Graft Copolymer Of Cotton Fabrics

In this thesis, to solve the problems of high content of inorganic salt and high colority in reactive dyeing, cotton copolymer was prepared by grafting2-methacryloyloxyethyltrimethyl ammonium chloride (DMC) onto cotton using ceric ammonium nitrate (CAN) as radical initiator in acid solutions under nitrogen atmosphere, which can avoid salt and color pollution in reactive dyeing and improve utilization ratio of dyes.Various reaction parameters were optimized to determine the suitable synthesis conditions of the cationic fabrics for achieving high dye fixation with appropriate cationic degree and salt-free dyeing fixation of Reactive Blue KN-R. The suitable reaction conditions: the concentrations of CAN and acid were15mmol L-1and0.1mol L-1, respectively, m(DMC): m(cotton)=0.5,30℃for180min. Nitrogen content and degree of cationization of modified cotton under above conditions were0.16%and0.114mmol L-1, respectively; meanwhile, salt-free dyeing fixation of Reactive Blue KN-R on the modified cotton was93.5%. ATR-IR was used to characterize the graft copolymer and XRD, SEM, TGA, DSC, strength testing and other methods were used to analyze its physical and thermal stability properties.The adsorption processes of three reactive dyes-Reactive Blue KN-R, Reactive Red M-3BE and Reactive Yellow M-3RE on the modified cotton fabrics were studied under50℃and30℃. Results revealed that the adsorption isothermal curves followed Langmuir model, and the adsorption was an endothermic reaction. Maximum adsorption amounts of the two M-type dyes were higher than the theoretical values, which indicated that covalent bonding formed between the fibers and dyes. Salt-free dyeing fixation of Reactive Blue KN-R, Reactive Red M-3BE and Reactive Yellow M-3RE on the modified cotton reached93.5%,98.9%and99.8%, respectively, which were27.7%,26.2%and22.3%higher than that of the conventional dyeing, and the dye reactivity was95.7%,99.7%and100%, respectively. Comparing to those of the untreated cotton fabrics, the K/S value and fastness properties of dyed cotton grafted with DMC increased greatly and dye penetrability was good. Formaldehyde content and pH of the dyed cotton fabrics were measured, and results showed the dyed fabrics satisfied the requirements of criterion Type-B. Furthermore, indexes of dyeing wastewater were measured; COD of dyeing residual liquid and soap liquid of salt-free dyeing conformed to first-order criterion and second-order criterion, respectively. Cationic cotton fabrics were dyed with reactive dyes including different functional groups in the neutral or weak base solutions. Results revealed that the M-type and K-type dyes with monochlorotriazme groups were suitable for dyeing without salt and alkali, KN-type dyes only containing vinyl sulfone sulfate as reactive group can dye cationic cotton under weak alkaline condition without salt. In addition, reuse of the DMC monomer and initiator was investigated to show the applicability of this modification, and monomers can be used more than three times. By choosing cheaper oxidant, persulfate, recycle of initiator CAN-Ce4+-Ce3+-Ce4+was achieved, alleviating shortages such as its larger dosage and high cost.In conclusion, the graft modification of the fabrics show promising prospect in application of salt-free dyeing.