The variation in the twist multiplier for maximum yarn strength in terms of the fiber properties of length. weight fineness, and uniformity of tenacity along bundle length is inferred from data based upon 15 1, 30, 1, and 40/1 yarns of a series of cottons having widely different fiber properties. The optimum twist multipliers that were calculated (1) from the above three fiber parameters (i.e., the tenacity-length uniformity hypothe sis); (ii) from the length and fineness, and (III) from the fiber length alone are com pared to the optimum twist multipliers detemined from the yarn tenacity vs twist curves. The tenacity-length uniformity hypothesis and the Sullivan theory are com pared by utilizing single cotton fiber properties. Considering all comparisons, the cor relation coefficients for theoretical to nommal values of optimum twist range from 0.64 to 0.96. Utilization in yarn twist of the ratio denoting uniformity of tenacity along bundle length in the tenacity-length uniformity hypothesis and of the ratio of single-fiber tenacity transfer in the Sullivan theory is illustrated.

Print cloth fabrics (80 × 80) were produced from yarns spun from cotton contain ing different percentages of short fiber. In the case of all fabric properties measured, with the exception of crease angle, increasing short fiber content resulted in significant changes adverse to quality, i.e., in decreased strength, elongation, flex abrasion, and tearing strength. Subjective properties such as appearance and hand were also de graded as the short fiber content increased. The above conclusions appiy equally to fabrics in the grey, bleached, mercerized and dyed, and resin-treated states. No con clusions could be drawn as to the effect of short fibers on weaving performance, because of the limited quantity of experimental material available.

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.

This investigation compares properties of a Type 128 sheeting woven with yarns spun from a blend of fihers differing widely in fiber fineness with comparable properties of a similar sheeting woven with yarns spun from a control cotton of the same average fineness. The data demonstrate that blending fine with coarse fibers in proportions of 60% to 40% does not detrimentally affect the important physical properties of grey, bleached, and bleached and dyed fabrics. Commercial acceptability evaluations showed that, in general, marketable bleached materials can be manufactured from a blend of extremely fine and coarse fibers. The dyed fabrics were not generally commercially acceptable due to nep imperfections. These findings, which showed that cotton fibers differing extremely in fineness can be utilized successfully when blended properly, revealed that the generally accepted opinion of unsatisfactory processing performance of blends containing fibers of widely different finenesses may be due to the inadequacy of present blending systems and methods rather than the properties of the fibers.

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 reported results compare the yarn properties of a high-strength (11.5 Pressley Index) Interspecies cotton with those of five other cottons having a comparatively wide range of fiber properties. The cottons were processed alike on conventional processing equipment into 18/1, 36/1, and 72/1 carded yarns using a range of twist multipliers from 2.75 to 5.75. The sliver and roving made from each cotton were measured for uniformity and the yarns were tested for uniformity, appearance, and strength. It was found that yarns made front the Interspecies cotton were as strong as those made from the much longer and finer Karnak cotton and stronger than those made from the other cottons. The Interspecies and Karnak yarns were about equal in uniformity with both being more uniform than the other control yarns. A limited statistical analysis of yarn breaking strength data indicated that fiber strength is more important to yarn strength than either fiber fineness or length.

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 proc essed 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 demon strated the necessity of controlling carefully spinning and other processing conditions in evaluating the elastic properties of cotton yarns.

Two cottons (Hopi Acala 50-an irrigated variety, and Variety A) and the single yarns used in a previous study, plus yarns spun from an additional cotton, identified as Variety B, form the basis for the 2-ply constructions covered by this report. The single yarns were spun (Z twist) using twist multipliers ranging from 2.75 to 5.75 in increments of 1.00. Each single yarn twist construction was 2-ply twisted (S twist) with the same range of twist multipliers. In addition, a "balanced" ply twist construction was made wherein the ply twist multiplier was found to be approximately 0.7 times the single yarn twist multiplier. Single yarn number was held as constant as possible by varying the spinning draft to compensate for the contraction due to twist. It was found that for cottons of comparable fiber length and weight fineness, the stronger fibered cotton produced the stronger 2-ply yarns. Also, differences in fiber strength do not affect twist-strength trends or percentage gain in strength of 2-ply over single yarns. The results of this study also indicate that fiber elongation is directly related to 2-ply yarn elongation.

Results are reported of a pilot plant evaluation of Pima S-1 cotton using an Egyptian variety, Karnak, and an American-Egyptian variety, Pima 32, as controls. The three cottons were processed alike on conventional equipment into a range of relatively fine single- and 2-ply yarns. Certain organizational details were varied within limits to aid in the evalution of the processing performance of the three cottons, and to determine the contributions each cotton made toward product quality. Each cotton was divided into three lots which were carded at 4, 6, and 8 lb/hr, respectively. Each lot was then combed, with 15 and 18% noils being removed. Twist- strength relationships were determined by spinning the yarns with a range of twist multipliers from 3.00 to 4.00 in increments of 0.25; draft-strength relationships were determined by spinning the yarns with a range of drafts from 14 to 53, using the twist multiplier found previously to produce maximum strength. The effect of the method of creeling was determined by spinning the same yarn number from a series of hank rovings both single and double creeled. Evaluation was made of gain in strength of 2-ply over single yarns using the same twist multiplier in both single and ply yarns. Also, an assessment was made of the response of these three cottons to three conditions of mercerizing and to subsequent dyeing. An analysis was made of opening-, picking-, and carding-waste percentages and of the uniformity of slivers and yarns. Yarn quality was determined by measuring skein and single-strand strengths, elongation, and appearance, and from the coefficient of variation of the strength values and Uster uniformity tester measurements. It was found that, within the limits of this study, the general processing performance of the Pima S-1 was equal to that of the Karnak and Pima 32 cottons. Regardless of the organizational variables used in the evaluation, the Pima S-1 cotton produced yarns of better appearance and uniformity than did the other two cottons. Also, yarns made from Pima S-1 were stronger than those made from Karnak, and were generally equal in strength to yarns made from Pima 32. Double creel produced stronger and more uni form yarns than did single-creel spinning for all the cotton varieties tested. The per formance of Pima S-1 in 2-ply constructions was equal to that of the two control cottons. The general response of Pima S-1 to mercerizing and to subsequent dyeing was slightly better than that of the other cottons.