The alkali centrifuge value (ACV) quantitatively measures caustic sorption in fibers and is related to the fibers swelling capacity. The ACV decreases when fiber swelling is restrained by crosslinks. In fabrics treated with dimethylolethyl eneurea (DMEU), the magnitude of decrease in ACV depended upon fabric construction and pretreatment. The basket- weave fabrics had lower ACV's, i.e., more restraint to swelling, than the plain-weave fabrics; the mercerized fabrics had lower ACV's than the scoured fabrics. Other data are presented to support the hypotheses deduced from the ACV relationships.

The alkali-centrifuge value (ACV) of cotton fibers is a quantitative measure of sorption from 15% NaOH solution. and reflects the fibers' swelling capacity. The ACV decreases when fiber swelling is restrained by a cross-linking agent. Cotton yarns, cross-linked with dimethyloldihydroxyethyleneurea (DMDHEU) to different contents by four different processes, had ACV's ranging from 260 to 160; the value for the noncross-linked control was 253. The caustic and the moisture sorptions depended upon the extent and nature of the reaction with the reagents. The cross-linking of cotton with DMDHEU, alone or in conjunction with Aerotex Resin Sp. (methylated methylol melamines) and the action of a caustic solution on the cross-linked structure seemed to be very complex. The properties of the cross-linked product depended upon many factors, such as preparatory process, content and distribution of the cross links, susceptibility of the cross links to a chemical, etc.

Differences in the ability of formaldehyde-crosslinked cotton fibers to swell are demonstrated in terms of alkali centrifuge values (ACV), i.e., the sorption of caustic solution of mercerizing strength. The wide range in ACV (310–50) emphasizes the extremes in sorptivity that can be achieved by differences in formaldehyde content and in method of introducing the cross links. In general, the ACV decreases with increasing formaldehyde content. However, ACV higher than that of the noncross-linked control cotton are reached for those samples in which a low percentage of formaldehyde was introduced into water-swollen fibers. Various hypotheses, based on ACV and related data, are presented pertaining to the alterations in fiber structure during the cross-linking processes and during the alkali swelling centrifuge test

Several series of cottons were dried by gin and laboratory methods to secure ranges in levels of drying. Moisture regain and density were determined after drying and after several types of mechanical working. The lower moisture regains for cottons excessively dried at the gin persist for long periods following drying but storage for several years essentially eliminates the influences of initial drying. Repeated exposure to high and low relative humidities at normal temperatures reduces but does not eliminate the drying effects. Cellulose density increases as lint moisture is reduced by gin drying. The changes in moisture and density suggest changes in cellulose structure but their direct influences on spinning behavior are inconclusive. Gin drying has a greater influence on moisture of cotton lint at opening and carding than in the second drawing sliver. By the latter stage, moisture differences caused by drying have been essentially eliminated, but the initial stages of mechanical processing take place when the maximum differences exist in moisture level of the lint.

The effects of heat and mechanical processing were followed, by means of the alkali centrifuge test, in cottons of different crop years. Laboratory heating alone, if held within the limits considered acceptable in ginning operations, did not significantly alter the average alkali centrifuge value (ACV). Mechanical manipulation of cotton while hot and dry, as in gin lint cleaning, increased the ACV. Mill processing increased ACV, and each process produced a constant change regardless of the degree of drying at the gin. Several factors, such as cotton maturity, microbial activity, stage of processing, determine the level of ACV. Certain properties of lint or yarns were related to ACV, sometimes through mutual relations to other properties which are more difficult to evaluate.

Yarn softness is evaluated quantitatively as the percent increase in yarn width under a definite lateral force. Single-yarn softness decreases with twist and increases with yarn number and fiber maturity. With the above parameters constant, softness has no relation to fiber linear density. An equation is developed for estimating single-yarn softness from yarn diameter and twist and from fiber maturity. The softness of 2-ply yarns as related to the component single yarns is discussed. For modified cottons, in creased fiber friction apparently contributes to the decrease in yarn softness. An equation is developed to estimate the single-yarn diameter from yarn number and twist multiplier. The possibility that the diameter of the 2-ply yarn is related mathematically to the ply yarn twist multiplier and to the softness of the original unplied single yam is discussed.

Iodine sorption and moisture sorption data and some density, x-ray, and infrared data have been obtained on partially acetylated (PA) cottons before and after progres sice deacetylation with 2 N hydrochloric acid or with N 2 sodium hydroxide. The re sults substantiate the accepted theory that in the partial acetylation of cotton the amor phous regions are acetylated first. They also show that deacetylation of PA cottons by these two reagents proceeds by different mechanisms. With hydrochloric acid. the acetylated amorphous cellulose is deacetylated more or less completely throughout the fiber before the, acetylated crystalline is attacked. With sodium hydroxide both are de acetylated simultaneously with little or no selectivity, so that deacetylation proceeds annu larlv from the surface of the fiber inward. The properties of the original PA cottons differed markedly from those of the same acetyl content obtained by deacetylation. The properties depended further upon the reagent used for deacetylation and on the acetyl content before deacetylation. These differences in properties can be attributed to differences in the proportions and distribu tion of amorphous, crystalline. acetylated amorphous. and acetylated crystalline cellulose within the fiber and also to differences in the fine structure. degree of lateral order, and stress patterns resulting from the inhomogeneity of the volume changes which take place during acetylation or deacetylation.

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An apparatus is described for measuring yarn softness in terms of the percent increase in yarn width when the yarn is subjected to lateral pressure between two parallel plane surfaces. Softness data obtained on a family of 31/2 cotton yarns have been presented as a contour diagram which, in connection with similar contour diagrams of other important yarn properties, shows the interrelationship of these properties over a wide range of single and ply twist combinations.

An apparatus for stretching and relaxing single fibers for the purpose of determining mechanical hysteresis losses is described. Results obtained on cotton, viscose rayon, and nylon fibers are compared with similar data previously obtained on cords from which the fibers were taken. Such comparison indicates that interfiber friction is probably the major cause of hysteresis energy losses in cotton and rayon tire cords under cyclic loads at low frequencies.