Measurement of Friction Between Single Fibers

When wool fibers which have been shrinkproofed by either the KMnO 4 /salt process or a dry chlorination process are examined with the optical microscope, normally, very little effect of the treatment can be seen. However, if they are straightened for the examination, a number of differences between treated and control fibers can easily be seen, especially if water is present. The principal effects are that the scales on the treated fibers, but not on the untreated, become less prominent as the fibers are straightened and that this change is much greater on the side which was the intrados of the crimp curve than on the extrados. Microscopic observation of fibers sliding on each other or over a diffraction grating also reveals effects of the treatment: the deformation of the scales of treated fibers is more plastic and less elastic than that of untreated and the sliding of the treated fibers is more heavily damped. From these and other observations, the conclusion has been drawn that these treatments degrade the protein inside the scales so that it becomes more viscous and less elastic, particularly when it is swollen by or dissolved in water. The epicuticle appears to be unbroken and still elastic.These results throw some light on the well-known disagreement between different workers about the changes produced in the coefficients of friction of wool fibers by the KMnO 4 /salt treatment.

Section: Effect Of Bilateral Differences Between Scalesmentioning

confidence: 99%

Some New Observations on the Effects of Mild Shrinkproofing Treatments on Wool Fibers

Makinson

1968

“…Yarn/yarn values were measured, using the twist method originally suggested by Lindberg and Gralen [13] for fibers. In this case, the yarns were wrapped around themselves three times and the input and output tensions were recorded in the same manner as that for yarn/metal friction.…”

Section: Details O F Yarn Testedmentioning

confidence: 99%

Knitting Performance of Wool Yarns: Instrumentation Studies 1

Knapton

1967

The knitting performance of a yarn, in terms of the work T y required to knit the yarn into jersey fabric, is measured hy use of a sensitive torque transducer located on the driving shaft of an experimental knitting machine. Using this technique, the knitting performances of a variety of worsted wool yarns are studied, and the effects of input tension, yarn/metal friction, yarn/yarn friction, twist level, and the WURLAN shrink-resist treatment on knitting performance are investigated.By the use of a mathematical analysis, the knitting behavior of a worsted yarn with changes in input tension is shown to be essentially similar to that predicted. Under normal commercial knitting conditions, T y is directly proportional to yarn/metal friction but independent of yarn/yarn friction. It is proposed that if the coefficient of yarn/metal friction ≤ 0.2, little trouble will be encountered in the knitting of wool yarns, and that the sometimes irregular appearance of knitted wool fabrics may be attributed to both spinning irregularity and the magnitude of yarn/metal friction. The knitting performance of a multi-filament nylon yarn is also shown to be dependent on yarn/metal friction.The use of yarn feeding devices at the standard knit construction reduces T y at any input tension, confirming that higher knitting speeds, increased efficiencies, and more regular fabric are attainable. The effect of yarn/metal friction on knitting performance is substantially decreased by the use of positive feed. An increase in twist factor from 1.8 to 2.8 had little effect on T y , although slightly increased values are found for hightwist yarns. However, the WURLAN interfacial-polymerization wool shrink-resist treatment increased T y as much as 60% at normal input tensions. This effect seemed to be unrelated to measured changes in yarn/metal friction and yarn flexural rigidity, but could possibly be due to changes in yarn/yarn friction. Some interesting observations of the mechanical performance of knitting machinery are also reported in this paper. '

“…Various methods are described in the literature for determining the coefficient of fiber-on-fiber friction [ 5,8,9). In these studies, the dependence of the observed coefficient on fiber finish, fiber diameter, normal pressure, speed, and the geometry of the system is pointed out.…”

Section: Friction Measurc~inc~ntsmentioning

confidence: 99%

Relationship Between Fiber Properties and Fabric Wrinkle Recovery1

Daniels

1960

This research was undertaken to obtain a better understanding of the role of fiber properties in determining fabric wrinkle recovery. For a variety of fibers a one-to-one correspondence was found between fabric crease-angle recovery and a modified tensile recovery parameter, i.e., the average value of tensile recovery (over the range of strains imposed during creasing) measured against a restraining force related to the coefficient of intertiler friction. From this index of recovery, it was predicted that fabric bending recovery would tend toward zero with decreasing strain (increasing radius of crease curvature). Such behavior was observed in the fabrics of nylon and Dacron 2 polyester fiber subsequently studied. The tensile recoveries under load, effective frictional restraints, and qualitative fabric-recovery features are presented. The results reported here indicate that the predominant fiber properties controlling fabric recovery can be determined without recourse to a complete mathematical treatment. Consideration of a simple, idealized model showed interfiber friction to be a property which must be considered in order to obtain even a qualitative description of the mechanism of fabric recovery from deformations involving small strains.