Study On The Influence Of Ca²⁺ Complexation On The Structure Of Bio-based PA56 Fibers And Its Dyeing Properties With Reactive Dyes

As a new kind of green fiber material developed in recent years,bio-based PA56 fiber has a broad application prospect in various fields.However,the effect of metal ion complexation on the structural properties of PA56 has not been reported.In addition,in view of the common problems of poor dyeing ability and low dye utilization when dyeing polyamide fibers with reactive dyes,this project first studied the effects of Ca²⁺complexation on the structure and properties of biobased PA56 fibers.On this basis,the effects of Ca²⁺complexation on the dyeing properties of PA56 fibers,especially on the dyeing properties of reactive dyes,were discussed,providing a basis for further improving the application properties of PA56 fibers and textiles.Through the experiment and exploration,the following conclusions are obtained:（1）Calcium chloride was used as the complexing agent,and the structure and properties of the samples were tested and characterized by treating bio-based PA56 and PA6 fibres in different solvents（water and anhydrous ethanol）.The test results showed that after treatment with calcium chloride solution,the positions of the N—H and C═O stretching vibration peaks of bio-based PA56 and PA6 fibres were red-shifted and the positions of the C—N.The melting point of the fibres decreased,the crystallinity and crystallinity decreased,but the crystalline shape did not change;the contact angle between the fibres and water decreased,the tensile properties of the fibres decreased and the surface of the fibres became uneven;the structure and properties of the sample fibres changed to a greater extent after treatment with calcium chloride ethanol solution than with calcium chloride aqueous solution,indicating that the ethanol After treatment with calcium chloride solution,the structure and properties of bio-based PA56 fibres changed to a greater extent than those of PA6 fibres,which is related to the irregular internal structure of bio-based PA56 fibres.（2）The dyeing rate of PA56-Ⅰfibres dyed with reactive dyes after complexation with calcium chloride in anhydrous ethanol solution was about 65%;the dyeing rate of PA56-Ⅱfibres obtained by adding calcium chloride directly to the dye solution was about 90%;the dyeing rate of PA56-Ⅲ fibres without complexation was about 25%.It can be seen that calcium chloride complexation is beneficial to improve the dyeing rate of bio-based PA56 fibres,and the increase in the dyeing rate of fibres is more obvious when calcium chloride is added directly to the dye solution.The dyeing kinetics of bio-based PA56 fibre adsorption by reactive red K-2G dye was in accordance with the quasi-secondary kinetic equation.The addition of calcium chloride to the dyeing solution substantially increased the equilibrium adsorption of the reactive dye on the polyamide fibre,and the dyeing rate and diffusion coefficient were also significantly increased and the half-dyeing time was shortened.The complexation reaction of calcium chloride with bio-based PA56 fibres under 80℃ dyeing conditions had less impact on the performance and structure of bio-based PA56 fibres and was still able to meet the criteria for subsequent production processing and consumption.（3）The optimized process conditions for reactive dyeing of bio-based PA56 fibres based on complexation dyeing were:dye mass fraction 3%（owf）,dyeing temperature 75℃,dye bath pH=6,dyeing time 40 min,anhydrous calcium chloride mass fraction 2%,bath ratio 1﹕20.After adding calcium chloride,the reactive dyestuff dyed bio-based PA56 fabrics had excellent soaping fastness and good rubbing fastness.Good colour fastness to rubbing.