Fiber Slippage of Spun Yarn During Tensile Tes

It is well-known that many complicated factors rct upon the strength of spun yarn, . In this report we have made some inquiry into factors that influence yarn strength. We have measured the number of fiber slippages when spun rayon yarn and nylon-rayon blended yarn are broken. (1) As a rule, the fiber slippage of both spun rayon and nylon-rayon blended yarns is less than 20% of the number of fibers in the yarn cross-section. (2) Fiber slippage in crimped spun yarn is worse than in uncrimped. Crimped spun rayon is poorer in utility of strength than uncrimped. influence yarn strength. (3) There is not always a correlation between utility of strength and fiber slippage. Clearly, therefore, all 11 factors except frictional theory (4) Within the range of practical number of twists the coarser spun yarn is, the less fiber slippage. (5) As the number of twists increases, fiber slippage decreases, but utility of strength attains a mix imum near the most suitable number of twists thereafter decreases. (6) In the range of practical number of twists (about 4.5-8 turns per centimeter), the theoretical equacion introduced by Agatsuma may be applied. (Of this more later.) (7) The above results apply to spun rayon yarn, but not to nylonrayon blended yarn. (8) In nylon-rayon blended yarn containing less than 50% nylon, there is more slippage of nylon than of rayon. If the nylon content exceeds 50%, there is more slippage of rayon.