Failure Mechanism
Material instability involves the loss of elastic recovery or structural integrity when the internal filament of a composite thread is compromised by heat or chemicals. In specialized finishing environments, core spun yarn degradation appears as a total loss of stretch because the elastane inner fibre has snapped within its protective cotton or polyester sleeve. The damage remains invisible until the fabric is subjected to tensile force during garment assembly.
Processing Cause
Exposure to elevated stenter temperatures during the setting process is the primary driver of polymer breakdown inside the sheath. Since core spun yarn degradation occurs rapidly at temperatures above one hundred and eighty degrees Celsius, finishers must carefully monitor dwell times in the oven. Acidic scouring agents also attack certain core types, reducing the service life of the finished textile.
Inspection Method
Verification of structural health is performed using a stretch and recovery test on finished knitted rolls. When core spun yarn degradation is suspected, a cross-section of the yarn is viewed under a microscope to confirm the state of the inner filament. Samples showing high growth after elongation usually indicate that the core has failed.
Long-Term Stability
Repeated laundry cycles and exposure to body oils further weaken core threads over time. Once core spun yarn degradation begins, the visual appearance of the fabric deteriorates as the outer fibres start to sag without the tension of the core. Garment lifetime is determined by the threshold where the stretch loss becomes perceptible.
