Geometric Profile
Microscopic examination of synthetic yarns reveals the physical outline of individual strands after extrusion. Analysis of this filament cross section determines the surface area and bulk density of the finished fabric. Circular profiles provide high strength, while non-circular profiles modify the moisture transport and hand of the knitted goods.
The choice of shape depends on the intended application of the yarn.
Optical Property
Light reflection off the yarn surface varies according to the geometry of the individual fibres. A trilobal filament cross section increases the surface luster by reflecting light along flat surfaces, which prevents the dull appearance common in round fibres. This geometric configuration also hides soil by diffusing incoming light.
The resulting fabric displays a brighter color depth.
Extrusion Variable
Melt spinning processes use specially shaped spinneret orifices to produce non-round profiles. Cool air quenching must solidify the polymer immediately as it leaves the spinneret to preserve the intended filament cross section before surface tension rounds the profile. Proper temperature control maintains the defined geometry across the entire yarn package.
A deviation in polymer viscosity during this phase leads to uneven profile definition and inconsistent yarn performance.
Performance Evaluation
Fabric breathability increases when non-round shapes create capillary channels that wick moisture away from the skin. Synthetic garments utilizing a modified filament cross section dry much faster than those made from round fibres. The capillary force depends on the groove depth.
