Influence Of Sequential Caustic Mercerization And Liquid Ammonia Mercerization On Dyeing And Wearability Of Cotton Fabric

This thesis mainly studies the effect of different sequencing mercerization on fabric dyeing property and wearing property.The pre-dyeing mercerization,post-dyeing mercerization and double mercerization processes were used to cotton fabrics.In the pre-dyeing mercerization,the samples of mercerized cotton by caustic soda(CM),liquid ammonia(LA),caustic mercerization before liquid ammonia treatment(CM/LA)and liquid ammonia treatment before caustic mercerization(LA/CM)were prepared.The SEM,XRD,TG and FTIR of cotton fibers were measured.Four reactive dyes(Reactive red 2,X type;Reactive orange 5,K type;Reactive Blue 21,KN type and Reactive Red 195,M type)were used to dye cotton fabric to investigate the exhaustion and fixation of reactive dyes,and the color fastness,water absorption,fabric strength and handle of the fabric were investigated.The fabrics dyed with three different types of reactive dyes(Reactive red 2,X type;Reactive orange 5,K type;Reactive Blue 21,KN type)were treated by caustic soda and liquid ammonia under tension and without tension,K/S value,the reflectivity,the dye stability,the color fastness,the fabric strength,elongation at break and handle were investigated.In the pre-and post-mercerization processes,the dyeing properties and wearability of knitted and woven cotton fabrics were compared.The result shows that the morphological structure,physicochemical properties,dyeing and wearability of cotton are changed.Compared with the original,the fibers of CM,LA,CM/LA and LA/CM become more plump and smooth,the crystalline structure transforming,the crystallinity decreasing further,the initial pyrolysis temperature moving forward,and there are differences between the hydroxyl region and the hydrogen bond vibration region in the infrared spectrum.CM and LA/CM are favorable for reactive dyes of macromolecular structure,while LA and CM/LA are favorable for dyeing small molecular structure.After the mercerization,the wicking absorption rate of the fabric is accelerated,the fabrics with LA and CM/LA are more conducive to the water molecules to obtain a better wicking absorption and softer handle than CM and LA/CM.The K/S value of CM(tension and without tension)increased more than LA(tension and without tension)post-dyeing mercerization.Mercerizing caused reactive dye hydrolysis and breaking the bond with the fiber,the result shows that the stability of three kinds of dyes(B21 < R2< O5)in caustic soda and liquid ammonia.Caustic mercerization can lead to more dye hydrolysis than liquid ammonia.The breaking strength and elongation are promoted by mercerization and the handle of mercerized cotton fabric by liquid ammonia gets improved.The double mercerization shows that the color depth of the fabric is not only dependent on the promoted dye exhaustion by the increase of the amorphous region of the fiber,but also depends on the dye-selectivity formed by the pore size of the fiber,the gloss of the fiber expansion and the fabric structure.The double mercerization of woven cotton fabric is helpful to improve the evenness of the fabric,while the evenness of knitted cotton is low.The cotton fabric after liquid ammonia mercerization is helpful to improve the handle of the fabric.