| In recent years,with the rapid growth of the national economy and the continuous deepening of economic structure adjustment,the people’s living level also raise continuously The requirements of basic necessities of life,especially in the dressing aspect of selective are increasingly higher than before,which requires that clothing fabric are not only wearing comfortable,gas-permeable,warm but also colorful changeable.Polyamide-6(PA6),as the main raw material of clothing fabric,has become more and more widely used in the field of clothing fabric.However the function of the conventional PA6 fiber has been unable to meet the increasing demands of human beings.Therefore,it is a matter of great urgency to develop PA6 fiber products with high performances and multi functions.In addition,although PA6 fabrics present the most vivid color among all fabrics,its low uptake rate and poor level-dyeing properties have been criticized for the industry.At present,the PA6 fiber produced by domestic chips often leads to streak and color difference problems in dyeing process for its poor dyeing stability.Almost all of the fibers with better dyeing properties were imported.In view of these dyeing problems related to domestic PA6 chip,in this paper,the influences of aggregate structure,amino group content,crystallinity and crystal structure of PA6 on dyeing behavior were studied in detail.On the basis of this,dyeing evaluation criteria was developed,which provides theoretic foundation for the PA6 fiber to improve its dyeing technology.Moreover,the refined PA6 powder was used to investigate the feasibility of PA6 chip dyeing,which opened up a new dyeing process for PA6.The key contribution in this method is a highly efficient and facile method for preparation of a and y phases of nylon-6.Based on the information contained in XRD、FTIR and DSC,temperature is one of the important factors affecting the crystal form of nylon 6.The γ-phase was obtained below 60℃ by the vapor of the ammonia solution diffuses into nylon-6/phosphate acid solution which can transit into a-phase above 60℃.Co-existence of the α-phase and y-phase was found at 60℃ and 70℃ by extending preparation time.As for a-phase,it is more thermal-stable and could be formed above 70℃ for 8h.From the images of SEM,the y-phase is composed of many pore sizes of holes,but the a-phase is the accumulation of irregular lamellae.Through changing the melt-extrution time of PA6 in capillary rheometer,samples with different amino group content were prepared.These samples were cooled in deionized water to obtain y-phase crystal,which is unstable and easy to transform into a-phase after heat treatment in boiling water.The analytic results showed that the content of amino groups was decreased with the increase of the melting time,nevertheless the relative viscosity and the content of the extractables increased.The prepared samples were dried at 80 ℃ about 24h in a vacuum drying oven,then they were mixed with appropriate amount of dry ice in a splintered machine and was pulverized into refined powders.Those powders with size of 55-60 mesh were chosen as the dyeing target.The results showed that when the PA6 powders have same crystal form and similar crystallinity,the dyeing rate decreased with amino groups content increased.When the amino group content keeps the same,the dyeing uptake rate of powders with higher crystallinity degree of a-phase is lower than that of the y-phase.This is because the unstable y-phase PA6 has large voids in aqueous solution,which enhances the mobility of molecular chain in the transformation process of y-phase into a-phase,favors to make the amorphous region more loose,and improves the diffusion and penetration of the dye,resulting in higher dye uptake... |
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