Relationships Between Pore Structure Of Cellulosic Fibers And Dyeing Behaviors Of Dyes

With the development of science and technology, it is becoming more important to reveal properties of materials though analysis of their microstructure. In the field of textile dyeing and finishing,when the research about crystallinity and orientation degree is not enough to explain some properties of cellulosic fiber, the pore structure of celluosic fiber was studied. Many literatures have focused on the direct dyes; however, it was lack of data about reactive dyes. The report about vat dye was rarer. It is also a lack of quantitative analysis of the relationship between the pore volume of cellulosic fiber and the amount of dye on fiber(fixation or K/S value). This thesis mainly studies the relationships between pore structure of cellulosic fibers and dyeing behaviors of reactive dyes or vat dyes, and trying to establish the function of pore volume and fixation of reactive dyes, in order to understand the dyeing properties of the fabric and to provide guidance about processing or production.The pore structure(e.g. pore size and distribution of volume) of cotton, ramie and viscose fiber was firstly studied by inversion size exclusion chromatography(ISEC). At the same time, the relationship between the pore structure and dyeing uptakes of reactive dyes or vat dyes were discussed. The orders of differential volume, cumulative volume and cumulative area were viscose > cotton > ramie. The difference in cumulative pore volume of smaller pores(Ф≤25.2?) was the most obvious. These fabrics were dyed using five reactive dyes with different molecular weight. Base on cotton fiber, fixation of C.I.reactive orange 16 and C.I. reactive red 23(MW 600-700) on viscose increased by 66% and 97%. The fixation of C.I. reactive black 5, C.I.reactive red 120 and C.I. reactive red 243 on viscose increased by 15%. The difference in fixation between ramie and cotton was slight. These phenomena could be explained by cumulative pore volume. The same is true for vat dyes.Cotton fiber and reactive dye were selected for discussing the effect of pore structure on diffusion or adsorption of dyes. The pore structures of mercerized cotton fiber, mercerized/liquid ammonia treated cotton fiber were characterized. After liquid ammonia treatment, the distribution of differential accessible volume moves to the small pore. It means that the cumulative volumes of pores below 28.8 ? were improved, but the others were decreased. The above reactive dyes were selected to dye the mercerized cotton fabric, mercerized/liquid ammonia treated cotton fabric. It was showed that liquid ammonia treating improved the dyeing rate and the equilibrium of C.I. reactive orange 16(smaller reactive dye).However, the dyeing rate and the equilibrium of C.I. reactive red 243(larger reactive dye) for mercerized/liquid ammonia treated cotton fabric were lower than those for mercerized cotton fabric. These phenomena were associated with the variation in cumulative volumes.Corsslinking agent SDP1 was selected to changes in the cumulative volumes in fiber. The variation in fixation of reactive dye was measured. The cumulative volumes of pore were decreased significantly with crosslingking increasing. It showed that the pore volumes accessible to dyes were decreased. The crosslinking in fiber closed or separated the larger pores. By nonlinear fitting, the relationship between the fixation of C.I. reactive orange 16(or C.I. reactive red 243) and the cumulative volumes of pores with diameter 25.2 ?(or 56.7 ?) meet the reciprocal function. The fitting coefficient was above 0.96.In order to verify the function, the mercerized/liquid ammonia treated was swollen by 15% NaOH. The fixation of C.I. reactive red 243 on mercerized /liquid ammonia treated cotton improved from 63.8% to 78.5%. It is because that the cumulative volumes of pores(Ф<74.4?) in fiber were improved.It is analyzed the feasibility of reactive dye as probe to rapid characterize the pore structure of cotton. From the result of mercerized/liquid ammonia treated cotton and mercerized cotton dyed with C.I. reactive orange 16, the positive ofΔK/S showed the increase in cumulative volumes of Ф25.2 ? pore. According to the accessible pore of reactive dye is related to molecular weight, the mixture of C.I. reactive yellow 15 and C.I.reactive blue 194(or C.I. reactive blue19 and C.I. reactive yellow 145) was choose to dye mercerized cotton and mercerized/liquid ammonia treated cotton. The color changes of dyed fabrics would reflect the variation in cumulative volumes of pores.Functional relation between cumulative volume of pore and fixation of reactive dye was established. It would provide solutions to the problem in dyeing and printing processes. When the cotton/viscose blends or mixed fabrics dyed with larger dyes, the color difference between the kinds of fibers could be narrowed. It was found that the color strength of mercerized/liquid ammonia treated cotton was lower than that of mercerized cotton by production. From the experiment, color strength of mercerized/liquid ammonia treated cotton was higher than that of mercerized cotton for smaller dye. The result of larger dye was similar to the phenomenon from industry. These ideas to solve the problem in production are not from crystallinity and orientation degree but from the information about pore structure.