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.
Lumen Collapse
Morphological Change
The flattening of the central hollow cavity in a cotton fibre occurs during the drying process after the boll opens. This lumen collapse transforms the circular cross section into a bean-like or ribbon-like shape with characteristic twists known as convolutions. The resulting geometry influences how the fibre reflects light and how it packs together during spinning.
Fibre Ripeness
Immature fibres possess thin walls that do not support the internal structure once the moisture evaporates. Consequently, lumen collapse in these fibres is more extreme, leading to dead cotton that resists dye uptake and creates white specks in finished fabric. Proper harvesting ensures that the secondary cell wall is thick enough to manage the transition.
Mechanical Property
Mechanical properties resulting from this process include a higher degree of inter-fibre friction. Without lumen collapse, cotton would lack the natural grip required to form a strong yarn at low twist levels. The convolutions allow the fibres to interlock, which provides the tensile strength necessary for high speed loom operations and knitting.
Mercerization Effect
Treatment with caustic soda causes the fibre to swell and regain a more cylindrical form. This reversal of the lumen collapse increases the luster of the fabric and improves its ability to absorb moisture.