Textile Research Journal

A method to measure cottenseed oil and oily seed-coat fragments in raw cotton and waste residues has been developed. Carbon tetrachloride is used to extract cottonseed oil from the Shirley analyzer waste of a known amount of cotton or from a waste residue. The amount of cottonseed oil is determined by quantitative infrared analysis, and can be related to seed-coat fragment content. Results of tests on cottons from several ginning studies show that both cottonseed oil content and seed-coat fragment content vary with ginning treatment. Excess cottonseed oil in cotton contributes to sticking problems in yarn manufacturing, with the problem being particularly acute at the card crush rolls.

There has been considerable controversy over the question of whether the epicuticle forms a continuous outer sheath on keratin fibers or surrounds each cuticle cell individually. The evidence advanced by earlier workers in support of the former concept is reassessed critically and reinterpreted in other ways. At the same time, the formation of Allwörden sacs on isolated cuticle cells and other results show that the latter concept is correct, viz, that the epicuticle surrounds each cell individually and, hence, forms part of the cell membrane complex.

The light-scattering properties of single fibers of wool, hair, and jute and filaments of nylon, terylene, and glass have been studied by scanning along their lengths with a He-Ne laser beam. The light-scattering profiles of the natural fibers suggest uniformity in the optical properties of the fiber materials and are, therefore, closely related to the geometry of the fibers. The optical properties of nylon and terylene, on the other hand, are observed to be very nonuniform along the filament. This nonuniformity is attributed to variations in (a) the orientation of birefringent domains of the filament material with the filament axis and (b) the crystallinity or packing density of the material. Because of this lack of uni formity it is not possible to define optical and dimensional parameters that are constants for these filaments from light- scattering data over any appreciable length (Ca > 0.5 mm). Glass fibers have light-scattering properties that vary along their length in a way that is determined by their method of formation.

Fiber-diameter measurements can be carried out by applying the principle of the diffraction of white light. An instru ment (Mikronmeter) based on this principle is described. A sample of randomly arranged fibers produces a circular diffraction pattern the size of which is determined by the diameter of the fibers. Well-trained operators can measure fibre diameters very accurately, while randomly chosen operators can determine fiber diameter with a 95% confidence interval of about ±0.8 microns. Occasionally, some operators cannot use the instrument correctly.

The significance and relative contribution of the various factors that contribute to the stabilization of the extended state of the keratin fibers have been investigated. In this context, the stress relaxation of extended keratin fibers in 7.2 M LiBr solutions, as well as their recovery and recrystallization behavior, were studied. A kinetic analysis of stress relaxation in 7.2 M LiBr at a strain of 60% indicated that the controlling mechanism is an SH-catalyzed disulfide inter change with an activation energy of 22.9 kcal/mole. The recrystallization in a stable β-configuration of the chemically molten and extended keratin fibers is only possible after a structural rearrangement which removes disulfide bonds from stressed positions. If this rearrangement is prevented, the β-crystallites remain unstable even after an extended re crystallization time. Stabilization of the extended state by the formation of stable covalent cross links is not possible, unless crystallization of β-crystallites is permitted. The formation of β-crystallites alone, on the other hand, is also not sufficient to stabilize the extended state, unless the β-configuration is supported by stable covalent cross links. After a melting-extension-recrystallization cycle at 96°C, the total longitudinal deformation of the keratin fibers approaches 125%, which would correspond to the theoretical α-β-translation distance.

Three wearer trials of mens socks are described. The trials tested the efficacy of the shrinkproofing treatments and the effect of blend ratio upon wear life. The 80/20 wool/nylon socks had about three times the wear life of similar pure wool socks. No socks failed through shrinkage. The wear life was unaffected by the type of shrinkproofing treatment. The socks which lost least fiber during wear and which retained the best appearance were those which had been treated with resin after manufacture. Irrespective of blends socks appear to be in moisture equilibrium with RH between 65 and 85%.

This study was undertaken to measure quantitatively the effect of temperature on the oxygen index values of several fabric samples of cotton, polyester, and their blends. The smoke density generated during the burning of these fabric samples at their oxygen indices was also studied at various temperature conditions. The results indicate a definite rela tionship of burning behavior with temperature, fabric weight, and composition of the blends. Two commercially avail able flame-retardant finishes were employed in this comparative flammability study of treated and untreated specimens. A novel instrument, which complies with standard laboratory procedures, was employed throughout this study, and it was found to be versatile, convenient, and highly reproducible in the generation of the data.

Dechant's method for determining the total accessibility of cellulose by exchange with deuterium oxide was modified for routine use with cotton fibers. Deuterated cotton was allowed to re-exchange with water or aqueous sodium hydroxide solution and the deuterium oxide content of the liquid used for re-exchange was determined by measurement of ir absorb ence at 2510 cm ¹. Sodium hydroxide solution (20%) was found to bring about re-exchange of that fraction of OD-groups which resist re-exchange with water, as demonstrated by ir spectra of deuterated and rehydrogenated cotton fibers. Ac cessibility to deuterium exchange was determined for selected cotton and rayon fibers and three series of immature cotton fibers. 'I'hese measurements correlated well with measurements of moisture regain and iodine sorption value made to obtain other estimates of the accessibility of the fibers.

A study was made of the chemical reactivity of wool in dimethyl sulfoxide (DMSO) as well as the effect of DMSO and related aprotic solvents on the physical properties of wool. Some functional groups in wool, especially amino groups of lysine and imidazole groups of histidine, are readily modified in DMSO in the presence of triethylamine by activated vinyl compounds (e.g., acrylonitrile and (di)vinyl sulfone). Treatment with vinyl sulfone increases the resistance of wool to oxidation by peracetic acid, suggesting that new cross links are present. Also studied were (a) the relative reactivities in aqueous, aqueous-DMSO, and DMSO media; (b) the supercontraction of wool and densification of felts by DMSO; (c) the effect of heating wool in DMSO on amino acid composition; and (d) stress relaxation of hair, including sulfhydryl- disulfide interchange. Our studies suggest that DMSO is a useful medium in which to modify wool with various reagents. In some applications, DMSO has advantages over water.

Graft copolymerization of methyl methacrylate was performed onto wool chemically modified with caustic soda, formic acid, thioglycollic acid, and sodium bisulfite using ferrous ion-hydrogen peroxide redox system at 45°C. The percent graft-on was found to be higher in modified fibers. The graft-on increases with reaction time up to about 10 hr. Some mechanical properties of such graft copolymers were studied. With polymer formation, the strength decreases a little, probably due to the initiator free radicals; the breaking elongation falls considerably, particularly in reduced fibers. The Young's static modulus decreases after acid and alkali treatment and increases after reduction. The modulus is found to decrease slightly with graft-on in normal, alkali-treated and formic acid-treated wool. However, in case of reduced wool, an initial increase of modulus with polymer uptake is followed by a decrease.

The use of N,N-diethylaziridinium chloride (DAC) as a coreactant catalyst for the reaction of cellulose with several N-methylol compounds has been investigated. This catalyst was effective in promoting reaction between cotton and all of the four methylol derivatives tested but especially effective in promoting the reactions of dimethylolethyleneurea and methylated trimethylolmelamine with cotton cellulose. These two cross-linking agents could be used in a delayed- cure process with DAC as the catalyst. Little reaction occurred with either of these reagents during delay periods up to 33 days and no increases in recovery angles were found in the delayed and uncured samples. The delayed-but-cured samples showed crease-recovery angles equal to those achieved in immediate cures.

A rapid and reproducible method is described for measurement of adsorption of particulate solids on fabrics or films and evaluation of dry-soil resistance. An Accelerotor drives the soil and samples along a circular path within a chamber. Impingement and degree of soiling can be continuously varied by changing the speed of the Accelerotor, the duration of soiling, and the amount of soil.

Soiling values of the new method correlate with soil resistance data obtained by other soiling methods involving me chanical work, such as tumbling and rubbing. A correlation exists also with nonabrasive soiling of stationary fabrics, unless the construction of the fabrics is markedly different or the transport of soil to the fiber surface determines soiling.

Simultaneous soiling of different fabrics was found to be competitive. Fabrics with the least soil resistance were preferentially soiled at the expense of the more soil-resistant fabrics. This alternative procedure has been used to enhance soil-resistance differences for visual evaluation.

It is shown that the resistance of a fluoropolymer-trealed fabric to oily particulate soil is not a function of its oil repel lency, but depends upon the nature of the polymeric finish, the substrate, and surface coverage.

Polymer film. Stress. Viscoelastic flow; equations of state; equations of motion; primary flow; stress field; surface velocity. Polymer-film flow.