Contribution of Core and Sheath Components to the Tensile Properties of DREF-III Yarn

The contribution of individual core and sheath components to the tensile properties of DREF-III yarn is reported here. Three different yarn types are made by the DREF-III system: staple viscose fibers in both core and sheath, staple viscose fibers in the core and staple PVA fibers in the sheath, and staple PVA fibers in the core and staple viscose fibers in the sheath. Because PVA fibers are soluble in water, they are removed afterwards with boiling water to produce individual core and sheath components. In all samples, the core-sheath ratio is kept at 50:50. The parameters discussed here are the core contribution factor, the sheath contribution factor, the core-sheath interaction factor, and various other structure- related parameters such as yarn diameter, helix angle, helix diameter, and mean fiber extent. Process variables are the spinning drum speed and the yarn delivery rate. The paper reports the effects of these process variables on tensile properties of the parent DREF-III yarn as well as individual core and sheath components. Structural changes due to removal of either core or sheath are also reported.