Louis A. Fiori

Effects of Cotton Fiber Fineness on the Physical Properties of Single Yarns

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 fine ness 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 impor tant 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 yarn- strength 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 de creased 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.

The Effect of the Short Fibers in a Cotton on its Processing Efficiency and Product Quality Part I. Affecting the Short Fiber Content by the Addition of Cut Cotton Fibers

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.

The Effect of Drawing-Frame Variables on Cotton Fiber Hooks and Parallelization and Processing Performance

A study was made of the effect of the drawing frame variables, sliver weight, total draft and doublings, draft distribution, back roll setting and weighting, and top- bottom second roll spacing on fiber parallelization, fiber hooks, and processing per formance. Sliver weight had a significant effect on fiber hooks, fiber parallelization, and processing performance, whereas the other processing variables had little practical effect, even though the effects observed were in many instances statistically significant. Fiber hooks increased and fiber parallelization decreased as the sliver weight fed to drawing increased. This led to an increase in spinning end breakage. An increase in draft and doublings increased fiber parallelization, but decreased sliver uniformity. The increase in fiber parallelization overshadowed the decrease in sliver uniformity, resulting in a decrease in spinning end breakage. These findings demon strate the need for achieving fiber parallelization, as well as sliver uniformity measure ments, to develop processing organizations that will result in optimum processing per formance and improved quality control.

Effect of Cotton Fiber Strength on Single Yarn Properties and on Processing Behavior

Fiber length, fineness, and strength are the properties which contribute the most to yarn strength. Yarn strength is considered to be the principal criterion of yarn quality. Recently, breeders have developed cotton varieties having fiber strengths which average from 25 % to 50% above normal. These new cottons of average length but with a high fiber strength will find a ready market if they can be processed efficiently and satisfactorily. It is the purpose of this study to determine the effect of the strength of the fiber upon the strength of the yarn. At a previous Cotton Research Clinic we reported on the effect of fineness of cotton fibers upon yarn strength, and the findings of this study were published in the October, 1951, issue of the TEXTILE RESEARCH JOURNAL. At some later date, we hope to have an opportunity of reporting on a similar study of the effect of fiber length on yarn properties. We plan to set up tables showing the values of the various fiber properties as they influence yarn properties, and from these tables we hope to derive a formula which will form a basis for predicting yarn strength for any cotton whose fiber properties are known. Such a prediction formula would be useful to cotton breeders in guiding them in their breeding work; it would likewise be useful to manufacturers in their selection

New Roving Twist Formula

The oldest roving twist formula on record, whose origin is unknown, is based on the premise that twist is proportionate to the square root of the hank (size) roving. This formula does not take staple length into account and is applicable over only a limited range of hank rovings. The formulas of Bissonnette [2], Brandt [3], Duerst [4], and Lawton [7] are based on both length and hank roving as factors influencing twist. However, twist determined by formulas based on these two factors does not give the

Blending Cottons Differing in Fiber Bundle Break Elongation Part I: Effect on the Properties of Combed Single Yarns

Two long staple cottons, differing in fiber bundle break elongation but having other pertinent fiber properties substantially equal, were blended in different percentages to permit a study of the effects of break-elongation on yarn properties and spinning etbciency. Yarn strength and elongation were affected by fiber elongation, with fibers having the highest fiber elongation exerting the greatest influence. Furthermore, nep formation increased linearly as the percentage of higher elongation cotton increased in the blend, indicating that neps are directly influenced by average fiber stiffness. It was also found that yarn toughness index correlated closely with yarn impact data, thus suggesting its possible substitution for yarn impact data. The inconsistency of end breakage of the warp and hlling yarns during spinning offered no conclusive evidence as to the relative spinnability of the cottbns and cotton blends investigated.

Blending Cottons Differing Widely in Maturity Part I: Effect on Properties of Single Yarns

The blending of extremely fine and coarse cottons was investigated as a possible way of economically using these difficult-to-market cottons in the blended form. Two cottons differing appreciably in fiber fineness (approximately 3.0 and 6.0 μg./in.) but having other pertinent fiber properties about equal were blended together to produce a mixture averaging about 4.0 μg./in. in fineness. For comparative purposes a control cotton also averaging about 4.0 μg./in. in fineness was used. The blended and control cottons were spun into coarse and medium yarns of varying twists and into yarn num bers suitable for weaving Type 128 sheeting (64 X 64). The spinning efficiency of the two cottons was evaluated, on a pilot plant basis, in terms of ends down per thousand spindle hours. Waste, nep count, yarn properties (skein and single strand strength, break elonga tion, uniformity, and grade), and end breakage rate in spinning were similar for the blended and control cottons. Microscopical examination of yarn cross sections did not reveal any migratory tendencies of either the fine or coarse fibers. For the same yarn number the blended and control cottons produced yarns of similar diameters and softness values.

The Effect of Short Fibers in a Cotton on its Processing Efficiency and Product Quality: Part II: Yarns Made by Miniature Spinning Techniques from Differentially Ginned Cotton

The conclusions reached by means of miniature spinning techniques with very small samples of cotton were similar to those obtained in Part I : changes in short fiber con tent do not affect the twist required for maximum strength hut do lower strength some what more than 1% for each 1% increase in short fiber content. These samples covered an exceptionally wide range of short fiber contents, from less than 1% to almost 20% by weight of fibers 3 in. and shorter. The very low short fiber content cottons were produced hy careful hand ginning techniques while the re mainder were obtained by differential ginning techniques.

Investigation of the Minimum Length of Cotton Fiber Effective in Single Yarn Tenacity

A systematic investigation of the translation of cotton fiber length distribution and fiber bundle tenacity into single yarn tenacity is reported. The mathematical model proposed is: Y = af (l, x) × S + b where Y is single yarn tenacity, a and b are constants, S is fiber bundle tenacity, l is length distribution of the cotton, x is critical length, and f(l, x) is a numerical value termed “effective weight” which is dependent upon the entire fiber length distribution. The investigation was carried out over a wide range of twists and yarn numbers, the latter ranging from 15/1 (40 tex) to 80/1 (7.2 tex). The optimum f(l, x) was selected, and it was found that fibers shorter than about 1/8 in. do not contribute to yarn tenacity. Similarly, a 1/8-in. portion of each longer fiber is ineffective. This may be viewed as implying physically that, on the average, the 1/8-in. tip at each end of each fiber does not contribute to the yarn tenacity. Hence, the degree of translation of fiber bundle tenacity to yarn tenacity is a function of the entire length distribution. An interesting finding of this investigation is that the “zero”-gauge fiber bundle test is superior to the ⅛-in.-gauge length test as a criterion for relating bundle to yarn tenacity if the zero-gauge value is modified by the effective weight, i.e. f(l, x) above.

The Effect of the Short Fibers in a Cotton on Its Processing Efficiency and Product Quality Part III: Pilot-Scale Processing of Yarns

By differentially ginning a single lot of Acala 44 cotton, various short fiber content levels were obtained. Yarns produced from these cottons showed the effects of increases in short fiber content; namely, reduced strength, elongation, and appearance grade. The twist required for maximum strength was found to be largely unaffected by changes in short fiber content, except for a medium yarn number for which a relationship was demonstrated. A graph showing the close relationship between the percentage of fibers less than 3/8 in. and those less than 1/2 in., calculated for a wide number of cottons, is included. Spinning efficiency is shown to be adversely affected by changes in short fiber content.