Research On The Flat-knitted Mercerized Coil Structure Variation Law And Properties Of Weft Cotton Fabric

According to the different mercerizing equipment,the mercerizing methods of knitted fabrics mainly include cylindrical mercerizing and flat width mercerizing.Flat width mercerizing can avoid the overfeeding,spreading,and skew of the cylindrical mercerizing into the cloth area,and the uneven reaction of the fabric with slight alkali.However,there is the problem of inconsistent changes in the loops of the fabric edge and the central area,which causes irregular deformation of the fabric.In this study,weft plain knitted fabrics with easily deformed loops were taken as the object of study.The changes of the fabric coil structure parameters of the non-mercerized fabric under unidirectional and bidirectional stretching conditions were studied.The structural parameters of the fabric loop in the stretched state and the relaxed state,and the relationship between the mercerizing conditions and the fabric wearability is explored.The main research contents are as follows:The mesh method is used to divide the fabric into different units,and the mercerized cotton fabric is stretched unidirectionally and bidirectionally.The structural parameters of the fabric loop(vector field and displacement field,loop height and loop distance,coil shape factor and shear angle).The study found that the displacement vectors of the fabric element nodes show different sizes and directions;the coils are prone to skew and other large deformation behaviors at the fabric edge,the node deformation is small in the center area and there is an elliptical uniform deformation area.The change of the distance conforms to the parabolic change law;the coil shape coefficients are distributed in gradients,and the coil shape has periodic changes;the shear angle is obviously layered,and there is an obvious stepwise law.Under unidirectional stretching,the deformation of the loop is large,and the change of the loop is uneven.Under the condition of bidirectional stretching,the loop shape is more stable.Under biaxial stretching conditions,the effect of different mercerizing conditions(alkali concentration,tension,temperature and time)on the loop structure parameters of the fabric under tension was studied.It was found that the effect of alkali concentration and tension on the fabric loop parameters is more large,temperature and time have little effect on fabric coil parameters.Under biaxial stretching conditions,the effect of different mercerizing conditions(alkali concentration,tension,temperature and time)on the coil structure parameters of the fabric in the relaxed state was studied.Comparing the fabric in the stretched state,it can be found that in the relaxed state.The shape of the fabric loop is more uniform,the loop change is more regular,and it has better coil structure parameters.When the fabric is in a relaxed state,when the alkali concentration is 200g/L,the tension is 5% of the expansion,the temperature is 50°C,and the time is 120 s,the area of the ellipse area in the displacement field accounts for 47.52%,and the loop height and pitch are consistent with the parabola.The change rule and the fitting degree are all above 0.95;the area of the central area with uniform fabric loops becomes larger,the maximum shear angle of the fabric changes from 89.3° to 90°,and the area of the maximum shear angle area increases.The relationship between different mercerizing conditions and fabric properties was explored,and the changes of shrinkage,style,wear resistance,breaking strength,moisture permeability,breathability and thermal insulation properties of blank samples and mercerized fabrics were studied.Compared with blank samples,mercerized fabrics have improved mechanical properties,softness,fuzzing and pilling properties,and thermal insulation properties,and reduced shrinkage,stiffness,moisture permeability,and air permeability;scanning electron microscopy(SEM)shows that the fibers of mercerized fabrics are naturally twisted partially disappeared,the fiber was elliptical.X-ray diffraction(XRD)test results showed that the crystallinity of the mercerized fabric was reduced from 0.471 to 0.466,and part of the cellulose I of the mercerized cotton fiber was converted to cellulose II.The best mercerizing conditions for cotton knitted fabrics are obtained by synthesizing the changes of fabric coil structure parameters and the changes of fabric properties under different mercerizing conditions.These studies clarified the relationship between the mercerizing process conditions and the changes in the shape of the knitted fabric,as well as the relationship between the mercerizing conditions and the dimensional stability.This is of great significance for improving the industrialization and low carbonization of knitted fabric open-width mercerization.