The elongation phenomenon of knitted fabrics under the action of longitudinal tension is divided into three situations: changes in organizational structure, changes in yarn twist, and fiber elongation.
1. Changes in organizational structure-changes in yarn spatial structure
It is a phenomenon in which the length of the knitted fabric loop increases and the width decreases under the action of a small external stretching force. This kind of fabric deformation can easily shrink the fabric through mechanical preshrinking, such as: overfeeding tentering, overfeeding drying, overfeeding calendering, blanket preshrinking and rubber blanket preshrinking.
2. Changes in yarn twist
It is the phenomenon that the yarn is stretched due to the effect of large external force, or under the effect of small external force for a long time and continuous stretching, so that the fabric does not have the opportunity to relax and shrink. The fabric shape change caused by this kind of yarn deformation is difficult to shrink if only through the finishing methods of overfeeding tentering, overfeeding drying, and rubber blanket preshrinking, but it can be processed by washing machine, loose dyeing machine, etc. The water immersion relaxes and shrinks.
It is a phenomenon in which the fiber is stretched under the action of a large external force, or under the action of a large external force continuously for a long time. The change in fabric shape caused by this reason cannot be recovered by mechanical preshrinking and water immersion relaxation treatment. Regenerated cellulose fiber fabrics, silk fabrics, and fabrics with less twist are more prone to fiber stretching due to excessive external force during continuous processing.