Changes in length of cotton yarns were monitored during treatment with liquid ammonia and with sodium hydroxide of mercerizing strength. Yarns were placed under levels of tension ranging from 1% to approximately 70% of average breaking strength, either before or after the swelling agent was applied. Some general relationships between method of treatment and the resulting yarn-length changes should be useful in understanding the physical changes that take place upon technical applications of mercerizing agents.

Yarns spun from high- and low-maturity cottons were mercerized in liquid ammonia in a continuous process, and in liquid ammonia and sodium hydroxide in skein form under various tensions. Both swelling agents produced similar changes in mechanical properties (breaking strength, tenacity, elongation-at-break, and initial modulus) under comparable conditions. Mercerization under high tension increased breaking strength and tenacity and decreased elongation-at-break. Slack mercerization in caustic resulted in elongations-at-break substantially higher than did ammonia treatment. A major difference between reagents was noted during treatment. When skeins were swollen slack and then restretched, much greater force was required to restretch ammonia-swollen skeins, and they could not be stretched as much as those that were caustic-swollen. Measurements of length changes in yarns during swelling, tensioning, and deswelling gave quantitative data to substantiate this observation. Differences in mechanism of swelling are discussed in relation to these findings.

Changes in length with increases in temperature have been determined for two flame-retardant cotton yams and fabrics—one treated with a zinc chloride-ammonia complex and the other treated with tetrakis(hydroxymethyl)phos phonium hydroxide, then cured with ammonia vapor. Other modified cottons, ramie, and glass-fiber yarns were also tested in flowing oxygen or nitrogen atmospheres. The elongation vs. temperature curves for Deltapine cotton yams and fabrics when under load indicate that results are influenced more by the chemical treatment or material than by the form or shape of the textile. Thus, flame-retardant cotton increases in length with increasing temperature until 300°C is exceeded; thereafter, contraction vitiates the initial elongation and continues until rupture or until the termination of heating at approximately 500°C. Measurements of this type are made possible only by the use of a recently developed thermal analysis system.

Fabrics of printcloth weight in plain and basket weave were crosslinked with dimethylolethyleneurea to 2, 5, and 10% add-on. Specimens were dried slack or under tension before curing. The amount of crosslinking, controlled by resin pickup, produced reasonably consistent nitrogen contents in samples when other parameters were varied. Among the properties measured were fiber density, fabric thickness and area changes, fabric tensile and wrinkle recoveries, and single- fiber tenacity and tensile recovery. Relationships of properties to nitrogen contents and among various physical proper ties were frequently influenced by tension, fabric construction, and pretreatment.

Fiber toughness, fabric construction, and pretreatment were found to affect abrasive wear in permanent-press trouser cuffs. Samples of Pima S-2, Hopi Acala, and Delta pine 15 cottons were processed into twelve constructions of print-cloth weight fabrics. Cross-linking with the dimethylol dihydroxyethyleneurea-type resin was applied as a continuous process to fabrics after scouring and after slack mercerizing. Nitrogen con tents of treated fabrics show that type of cotton, fabric construction, and pretreatment affected the amounts of resin reacted with the fabric. Pima cotton had the lowest and Deltapine the highest level of nitrogen in almost every fabric construction. Pima cotton fabrics showed less wear during conventional abrasion test and laundering and greater crease-recovery angles than did the other cottons. Cuffs of basket-weave fabrics with 0.87% nitrogen showed less crease wear during laundering than did plain weave at 0.64% nitrogen. At comparable nitrogen content, slack-mercerized fabrics were more durable at a higher crease-recovery angle than were cuffs made from scoured fabrics.

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.

Fabrics made from lint cotton subjected to twelve combinations of ginning practices —seed cotton cleaning, lint cleaning, and drying levels—were tested as gray, bleached, and resin treated fabrics. The seed cottons dried to the lowest moisture level before ginning produced the weakest gray fabrics. Bleaching caused no accentuation of their differences in breaking and tearing strengths which could be associated with the ginning practice since strengths of all twelve fabrics were reduced about the same amounts. Resin treatment and laundering decreased the differences in strengths among fabrics. Density of cellulose was slightly higher for the three lots dried to the lowest moisture level. Moisture regains of the bleached fabrics were essentially equal. Alkali centri fuge swelling values were more closely associated with fiber fineness than with the ginning practices. Among the fabrics, differential dyeing detected differences asso ciated with fiber fineness but not with ginning practices. Degree of polymerization was reduced by bleaching but showed no consistent relation to seed cotton treatment. Inconsistencies among samples within groups do not permit conclusions to be reached as to effects of seed cotton cleaning or lint cleaning.

Yarns from samples of Pima S-1, Hopi Acala, and Coker 100 Wilt varieties were scoured, chloroform extracted, mercerized, and decrystallized with anhydrous ethylamine without tension. Breaking loads for yarns immersed in solutions when compared to those in water were essentially unchanged by ethylamine but decreased appreciably by sodium hydroxide. Untreated yarns in water showed decreases in strength with in creases in water temperature. Sodium hydroxide caused yarn to shrink in length as much as 35% but ethylamine only about 17%. Yarn shrinkages were related to in creases in cross-sectional areas of fibers and to cell sizes of the two complexes. Fiber lengths after treatments were unchanged by scouring or extraction but decreased by the sodium hydroxide and the ethylamine. Mercerization at normal length caused a reduc tion in the percentage decrease in single fiber and bundle tenacities as the gauge length was increased. Strength increases during mercerization are attributed to increased uni formity of strength along the fiber length.

The poor spinnability of some lots of gin-dried cotton has been attributed to over heating of the seed cotton. To determine what changes in the lint might be responsible, two series of gin-dried cottons and one series that was flash-heated in the laboratory were studied. Appropriate physical and chemical properties of the lint were measured, such as fiber length distribution, single-fiber and fiber-bundle strength and elongation, moisture regain, nepping potential, fiber friction, microscopical swelling, alkali swelling, wet tability, fluorescence, copper number, carboxyl content, pH, infrared spectra, and wax properties. Limited spinning and weaving tests allowed yarn and fabric properties to be measured. Nearly all tests showed no evidence of radical permanent changes in lint properties. The one significant finding was an altered fiber length distribution in some heated lots such that the proportion of shorter fibers was increased while the percentage of long fibers was slightly decreased. This change appeared to be correlated with poorer yarn appearance and uniformity, a slight reduction in yarn and fabric strength, and poorer resistance to flex-abrasion. A blend of unheated lint with enough short (cut) fibers to give a fiber-length distribution approximately the same as that of a gin-overheated lot produced yarns and fabric with properties in close agreement with the overheated lot whose fiber-length distribution was approximated by the blending. Laboratory tests showed that fiber strength was lower when tested immediately after heating—that is, when the moisture regain was temporarily greatly reduced. From this finding it is deduced that the change in length distribution is the result of excessive fiber breakage when lint is subjected to mechanical agitation at too low a moisture content.

potentials ofcottonseed slurries described inthis paperwasdeveloped asanadditional toolforin- vestigating deteriorative changes whichoccur inseeds during storage. Tech- niques previously employed inthislaboratory (9,10,17),involving the measurements oftheproduction ofheatandoftheformation offreefatty acids intheseedoil, measure onlytheendproducts ofmetabolic activity. Inaddition todataobtained bythese measurements, itisdesirable tolearn moreabout thebiological systems incottonseed asaffected byconditions of maturity, harvest, handling andstorage, information whichwouldbe gained bystudies ofspecific enzymesystems. Asapreliminary tothese studies, itwasconsidered helpful toobtain anoverall picture oftheoxidiz- ingandreducing systems intheseeds. Suchanindication isgiven inthe measurement ofpotentials ofseedslurries under aerobic andanaerobic con- ditions. Patterns areobtained whichshowthecomparative vigor ofthe oxidizing andreducing properties ofthedifferent lots ofseeds fromwhich these slurries areprepared. Oxidation-reduction