Structural Vulnerability
Structural degradation in composite textile strands occurs when the protective outer sheath separates from the central elastic or high-tenacity core. This degradation, known as core-spun yarn damage, undermines both the strength and the appearance of the finished knitted or woven fabric. In most cases, the failure becomes visible during subsequent high-speed winding or knitting processes.
This vulnerability is especially prominent when elastomeric cores are used.
Degradation Mechanism
Mechanical stress during fabric forming creates frictional forces that pull the staple fiber sheath away from the filament core. When the adhesion between the core and the sheath is insufficient, the sheath slides along the filament and accumulates in dense slubs or clusters. This slippage leaves long sections of the core filament completely exposed and unprotected.
These bare sections are highly susceptible to chemical attack during bleaching or dyeing, leading to complete filament rupture. The localized loss of elasticity creates visible thin places and structural weaknesses in the finished garment. Additionally, the stripped filaments can snag on guide needles, causing machine stoppages and fabric defects.
Production Assessment
Routine laboratory inspections verify yarn integrity prior to knitting or weaving. Technicians run yarn packages through specialized friction testers that simulate the mechanical forces of commercial knitting machines. The frequency of filament exposure is counted over a standard length to determine the damage index.
This assessment allows mills to reject low-cohesion batches before they enter production.
Performance Impact
Garments produced with compromised yarns exhibit poor stretch recovery and puckered seams after laundering. Elasticity fails in localized areas, which alters the fit and lowers the commercial value of the product. Ensuring core coverage maintains the durability of stretch garments.
