Thermodynamic Analysis of Hydrolyzed Polyurethane Filament Failure during Dyeing
Hydrolytic polyurethane breakdown during high-temperature dyeing occurs via acid-catalyzed ester cleavage, requiring polyether backbones and strict pH control.
Core Spun Yarn Failure
Yarn Rupture
Mechanical breakdown of a composite yarn occurs when the protective outer sheath separates from the central core filament under load. In stretch fabrics, core spun yarn failure represents a major quality defect that leads to permanent fabric deformation. This structural degradation typically involves the sliding of the cotton or viscose wrapper away from the elastomeric core.
Sheath Slippage
Friction loss between the staple fibres and the continuous core filament is the primary initiator of this separation. When the yarn is stretched, the elastic core extends while the sheath fibres remain in their original state. Insufficient twist during spinning fails to bind the cotton wrapper to the elastomeric core.
Under repeated stress, the outer wrapper shifts to form thick and thin areas along the yarn length.
Mechanical Stress
High friction during commercial sewing or knitting speeds up the deterioration of the poorly bound composite structure. Sewing needles operating at high cycles per minute generate localized heat that weakens the inner synthetic filament. Once the core is exposed, it breaks or slips, leaving the outer sheath to gather in lumps.
This localized bunching creates a ribbed appearance on the surface of the finished garments. Visually, the fabric shows puckered areas that cannot be corrected by pressing.
Mill Testing
Regular evaluation of core-spun fabrics through cyclical stretch testing identifies defective yarn lots before they undergo garment manufacturing. Measuring the permanent set after loading provides a clear indicator of structural integrity.