49--INVESTIGATION OF THE FRICTION AND BREAKAGE OF FINE-FILAMENT NYLON TOW DURING DRAWING.

All investigation is reported of factors (i.e., frictional behaviour and tensile properties) relating to the breakage of nylon 6.6 tow, consisting of many thousands of fine monofilaments, during a commercial process in which low is drawn by passing it over a series of rotating steel rolls. In a simulated-test experiment, the frictional behaviour was determined of a stationary length of the fine-filament tow lapping a rotating steel roll with different surface finishes. The friction depended on the roll speed, the effective load, the viscosity of the aqueous ‘finishing’ solution, and the roll-surface finish. Filaments began to break when the effective coefficient of friction reached 0.40–0.45. Friction (and filament breakage) were least with dry tow and were largely independent of roll-surface finish and relative sliding speed (above about 2 ft/min). The addition of the aqueous ‘finishing’ solution used commercially reduced both the yield and the ultimate tensile strength of the nylon (water being the effective weakening agent) and increased the friction of the tow against the roll surface. Friction increased with increase in solution viscosity and this, together with a marked speed effect, indicated hydrodynamic-type lubrication. This was promoted, with a higher relative sliding speed being attained before filament breakage, by the use of a medium-to-rough roll-surface finish. Friction due to viscous sheaf can be reduced by decreasing the product of the relative sliding speed and the fluid viscosity. The factors that may be applied to the commercial process to reduce filament breakage in the drawing of fine-filament tow are outlined. [ABSTRACT FROM AUTHOR]