Quantifying Radial Fixation Gradients in Ultra High Twist Viscose Ply Yarns under Dynamic Alkali Steaming
Dense viscose ply yarns require controlled swelling alkali blends to eliminate core fixation gradients during dynamic steam fixation.
Sodium Hydroxide Padding
Concentrated Alkalization
Liquid chemical application via heavy squeezing rollers provides a rapid and uniform distribution of reactive agents across a moving textile web. For high-volume cellulosics, sodium hydroxide padding applies a concentrated alkaline solution to swell the fibers and increase their chemical reactivity. This method ensures deep penetration of the alkali throughout the yarn structure.
Mercerization Processing
Fiber swelling alters the physical shape and internal structure of cotton from a flat ribbon to a rounded cylinder. When sodium hydroxide padding is utilized in continuous mercerization ranges, it breaks down the crystalline structure of the cellulose to increase amorphous regions. This structural shift permanentizes the luster and improves the dimensional stability of the finished apparel.
The treated fibers acquire a higher affinity for moisture, which subsequently improves the efficiency of subsequent dyeing and finishing chemicals.
Tension Control
High pulling forces must be applied during the chemical swelling phase to prevent the fabric from shrinking excessively. If sodium hydroxide padding is conducted without sufficient warp and weft tension, the cotton fibers will contract, resulting in a dense and heavy fabric with poor drape. This tension management is monitored closely at the padder exit to preserve width.
Dyeability Enhancement
Swollen fibers present a larger internal surface area that holds more dye molecules during subsequent coloration. Implementing sodium hydroxide padding allows the fabric to achieve deeper shades with less dyestuff, optimizing production costs. This process also enhances the brilliance of the finished color.