Elastic Performance
The time-dependent return of a deformed yarn to its original dimensions after the removal of a stretching force determines the performance characteristics of stretch fabrics. This viscoelastic yarn recovery combines both immediate elastic recovery and a delayed, slow recovery that is driven by molecular rearrangement within the polymer chain. It regulates how well a garment maintains its shape over repeated wear cycles, preventing the fabric from bagging or losing its compressive properties.
Deformation Kinetics
Spandex and other elastomeric yarns show a distinct delay in their return to initial length after being stretched on a tensile tester. Measuring the viscoelastic yarn recovery involves holding the yarn under tension for a set period and then tracking the rate of length retraction over time. This rate is influenced by the chemical structure of the polymer.
Finishing Control
High heat-setting temperatures applied during fabric finishing can alter the molecular structure and reduce the recovery capability of the yarn. Optimizing the viscoelastic yarn recovery prevents the fabric from becoming baggier after wash-and-wear cycles. This optimization is a key concern for activewear manufacturers.
Inspection Metric
Laboratory technicians utilize standardized relaxation periods to ensure that elastic yarns have fully settled before measuring fabric dimensions. Discrepancies in the viscoelastic yarn recovery between yarn shipments can lead to puckering and distortion in finished garments. This metric must be verified for stretch-sensitive knitwear.
