Study On Dye Aggregation Behavior And Cellulose Microporous Structure

Cotton fabric is widely used in clothing and home furnishing industry for its soft,comfortable and excellent wearability.Reactive dyes are the first choice for cotton fabric dyeing because of their high color fastness,bright color and strong applicability.However,dyeing fabrics with dyes is a complex process.At present,dyeing theories mainly focus on qualitative analysis of dyeing process from a macroscopic perspective,but research methods are relatively fixed and lack of innovation.In addition,there are few studies on the process and mechanism of dye diffusion into fibers,and there is a lack of quantitative analysis of the relationship between dyes and f ibers.This paper mainly discusses dye dissolution and aggregation and fiber pore distribution.The main research contents and conclusions of this paper are as follows:Firstly,the effects of concentration,electrolyte and soda dosage on the aggregation s tate of dyes were studied by ultraviolet spectroscopy,light scattering and two dimensional nuclear magnetic diffusion sequence spectrometry.The aggregation degree of C.I.active blue 194 and C.I.active orange 16 increased with the increase of the concen tration of the dye s olution,the UV absorption spectrum showed red shift phenomenon,and the dye molecules mainly had J-type aggregation,the diffusion coefficient decreased to stable with the increase of the concentration of the dye solution,and the part icle size of the dye solution increased from 1 nm to 7nm with the increase of the concentration.Adding sodium salt,soda and other substances will promote the aggregation of the dye,the average particle size of the dye increases to about 100 nm,but high salt concentration will lead to precipitation at the bottom of the dye,so adding excessive electrolyte should be avoided to prevent dye waste and uneven dyeing in the dyeing process.The morphology and pore size distribution of bleached and mercerized cotton fibers were studied by X-ray diffraction,nitrogen adsorption,differential scanning calorimetry and low field NMR.For dry cotton fibers,XRD shows that the crystallinity of the f ibers decreases and the amorphous area increases after mercerization.BET results show that the adsorption surface area of mercerized cotton is larger,the adsorption capacity is increased by 13.6%,and the fiber pore size is between 0-10 nm.For wetted co tton fiber,only group water exists in the completely dry state.With the moisture absorption and swelling of the fiber,bound water and free water appear successively,so the wet fiber co-exists three distribution states: group water,bound water and free water.The pore size distribution of bleached cotton is around 50 nm,and that of mercerized cotton is around 80-100 nm,and the pore size distribution of mercerized cotton is more uniform.In low field N MR analysis,the linear function relationship betwe en the integrated signal intensity and water quality of different fabrics was established,and the fitting coefficient was above 0.99,which could provide a new method basis for fiber type identification.Theoretical analysis of pure dye solution dye molec ules can all enter into the fiber to complete dyeing,but the actual dyeing process will add a variety of dye A IDS,resulting in the formation of large size of the dye molecules aggregate and can not achieve complete dyeing.