Cotton Yarns in Continuous Wet Processing Engineering
Continuous wet processing of cotton yarns demands precise control of yarn structure, swelling draft, liquor application, and transport tension to assure performance.
Mercerization Draft
Tension Application
Longitudinal tension defines the ratio between the delivery speed and the entry speed of fabric during caustic treatment in a continuous range. By controlling the mercerization draft, a mill can manage the amount of stretch or shrinkage that occurs while the fibres are in a swollen and highly plastic state. This mechanical setting is a primary determinant of the final lustre and strength of the processed goods because it dictates the degree of molecular orientation.
Dimensional Control
Stretching the fabric in the presence of sodium hydroxide prevents the natural tendency of the cotton fibres to shrink. A higher mercerization draft increases the alignment of the cellulose chains and improves the light reflection of the surface. Most industrial ranges operate with a draft between one and five percent.
Fibrous Alignment
Molecular orientation becomes more uniform as the draft pulls the swollen fibres into a straight path. When mercerization draft is applied correctly, it maximizes the increase in tensile strength that comes from the chemical treatment. Consistent tension ensures that the dye molecules can penetrate the fibre structure more evenly.
Lustre Quality
Surface brilliance is achieved only when the tension is sufficient to smooth out the convolutions of the cotton fibre. If the mercerization draft is too low, the fabric remains dull and may even lose dimensional stability. Proper calibration between the width ways tension and the length ways draft is required for a premium finish.