34—COTTON YARN STRUCTURE Part IV—THE STRENGTH OF TWISTED YARN ELEMENTS IN RELATION TO THE PROPERTIES OF THE CONSTITUENT FIBRES

Abstract

The strength of a yarn element depends on the strength of the constituent fibres, which may be measured by the Pressley bundle test. As the twist in the element increases the strength increases to a maximum and then decreases, the maximum strength being a compromise between the effect of the cohesion between fibres produced by the twist and a reduction in strength due to the inclination of the fibres to the yarn axis. The maximum element strength when corrected for the fibre inclination is less than the Pressley strength because of the unequal stressing of fibres at the core and the surface of the element. A formula is developed relating the maximum strength of the yarn element to fibre characters.