Forty-three cottons, varying extensively in fiber properties, were used to show the relationship between cotton fiber properties, particularly fiber bundle break elongation, and the properties of a coarse and medium yarn. In addition, there are presented some practical aspects of a speculative nature based on the results. The cottons were processed into a series of yarns of varying twists. Fiber break elongation, along with five other fiber properties (length, fineness, strength, length variability, and maturity), was correlated with yarn break elongation at twists for maximum skein strength, maximum single strand strength, and at two constant twists (4.00 and 5.00 T.M.).It was found that yarns produced from these cottons varied considerably in strength and elongation at break. Yarn strength and break elongation were found to be directly related for the commercially grown short and medium staple cottons, but the long staple and the experimental, strong-fibered cottons were found to be anomalous in that they produced yarns whose strength was disproportionate to their fiber break elongation.Based on multiple correlation analyses, fiber break elongation ranked first and strength ranked second in importance as contributors to yarn elongation for a 30/1 yarn at twists for maximum strength.Secant modulus (average stiffness) and "toughness" index of fibers and yarns are suggested as quality indices for evaluating processing efficiency. This study also demonstrated the necessity of controlling carefully spinning and other processing conditions in evaluating the elastic properties of cotton yarns.

The effect of carding rate and cylinder speed on fiber hooks and spinning performance was investigated for an irrigated Acala 4-42 cotton. It was found that increased carding rate increased minority and decreased majority hooks. The rate at which the minority hooks increased was greater for the Acala 4-42 cotton than a Deltapine cotton previously investigated. Generally, second-drawing sliver uniformity and end breakage were not affected by increases in carding rates. High carding rates resulted in less noils being removed without detrimentally affecting fiber length, yarn properties, or end breakage. Yarn imperfections and minority hooks of card sliver were related, indicating that, possibly, the phenomenon which produces minority hooks also produces neps and, thereby, yarn imperfections. This limited study seems to demonstrate that each type of cotton has its own peculiar fiber-hook formation pattern as carding rate is increased. The practical application of the research is briefly discussed.

The effects of the single fiber property fiber fineness on the physical properties of single yarns, both coarse and fine and of varying twist, were investigated. To permit the study of fiber fineness while maintaining other important properties approximately constant, a special technique was used which controlled the length factor by reducing all the cottons to common quartile and mean lengths. The cottons selected—Seaberry Sea Island, Mesa Acala, Tanguis, and Rowden 41—B—represented extremes in fineness, ranging from 2.9 to 5.6 μg. per in., and had other important fiber properties approximately equal. The study showed mainly that a relationship exists between fiber fineness and the turns per inch required in a single yarn to obtain optimum yarnstrength benefits. Low-twist yarns decreased less rapidly in strength from maximum strength when made from fine than when made from coarse fibers. In contrast, high-twist yarns decreased more rapidly in strength when made from fine rather than when made from coarse fibers. Yarns made from coarse fibers required more twist to attain maximum yarn strength than those made from fine fibers. The study also revealed that fiber fineness does not materially affect yarn elongation. In addition, it was found that fiber fineness is a critical factor of roving twist.THAT a relationship exists between cotton fiber properties, both individually and collectively, and yarn and fabric properties has been known from practical experience since the days when the spainning wheel was the only yarn producer.The relationship of fiber properties to the yarn property skein strength has been confirmed by means of statistical methods by many investigators. By substituting in the equations derived by some of these investigators the values obtained by measurements of certain fiber properties, yarn skein strength can be predicted within practical limits. But even the most successful of these prediction formulas are inadequate when it is desired to determine the effect of individual fiber properties on spinning quality. For example, length and fineness are properties hitherto so closely correlated that it has not been possible to evaluate statistically the distinct effect of each on yarn properties. Moreover, the statistical approach attempts to rank the fiber properties in relation to yarn skein strength only, without attempting to explain any effects on single and plied yarns of varying twists, product uniformity, processing behavior, or fabric quality.

The effect of the short fiber content of a cotton on yarn and fabric properties and processing efficiency, long a speculative and controversial subject, is investigated to a limited extent in this paper by the technique of cutting sliver into and ¼- and ½-in. segments and adding the resulting short fibers to the parent cotton. The results indicate that increases in short fibers are detrimental to virtually all yarn and fabric properties and require increased roving twist for efficient drafting during spinning. A 1% increase in fibers shorter than 3/8 in. causes a strength loss in yarns of somewhat more than 1%. The quantities of cotton processed for this paper were insufficient to draw conclusions on neps, waste, or processing efficiency. The effect of short fibers on these properties will be considered in subsequent papers.

No abstract