Yarns composed of fibers with different frictional coefficient were prepared by washing wool plain fabrics (muslin) under various conditions.
Method of measuring the number of twists (Ns) in the above yarn after a tension is applied till the fibers begin to slip was studied by using a twist counter. Moreover, the relation between the number of untwists (Ns) and the frictional coefficient were studied and the results were as follows:
1. The number of twists (Ns) were obtained from the difference between the original number of twists and the number of untwists (Nʀ). From the measurement of the number of untwists (Nʀ) the following can be concluded.
(a) The more tension applied to the yarn the more difficult it was to distinguish the difference in the frictional coefficient.
(b) The lower the speed applied to untwist the yarn the more distinct difference in the frictional coefficient was obtained.
2. The product from the number of twists (Ns) and the frictional coefficient was nearly constant.