Textile Research Journal

A new "moving-cavity" texturing technology has been developed. The mechanism of texturing consists of yarn striking a moving screen surface to initiate crimp and then being further crimped and "set" in plug form within a cavity. The effects of design and processing conditions to texture poly(ethylene terephthalate) (polyester) yarn (150/ 34) at 2,700 mpm are discussed. The textured yarns have good texture levels and are uniform.

The feasibility of the Southern Regional Research Center's cotton particulates analyzer (CPA) was studied. The lint, fly, dust, and trash fractions of cotton are dynamically separated and recovered by mechanical and pneumatic means, and material losses from ginned cotton, when processed by the CPA, are statistically insignificant. Analysis by difference, heretofore required because of a significant loss of material when the Shirley Analyzer was used, has been eliminated.

The uniaxial-tensile and bending properties have been examined for a series of wool and wool/polyester woven apparel outerwear fabrics. The fabrics tested include a wide range of laboratory-produced woven materials (varying systematically in weave structure and the ratio of the two yarn curvilinear lengths) and also a range of commercially-produced woven fabrics. The fabric load-extension curves and yarn- decrimping curves are analyzed and discussed in terms of the following dimensionless parameters: the normalized tension per thread (the applied tension divided by the yarn-bending rigidity and multiplied by the square of curvilinear length in the extended direction); the relative yarn or fabric extension (the yarn or fabric extension divided by the yarn crimp); the initial fabric tensile modulus (i.e., initial slope of the normalized tension vs. relative extension curves); the yarn-decrimping modulus; the relative energy of stretching (i.e., area under the normalized load-extension curve); and the energy loss due to hysteresis (i.e., area of the hysteresis loop of the normalized load-extension curve during tensile-recovery measurements). Inelastic and elastic parameters are described for the fabric-bending hysteresis curves. Fabric tensile and bending properties are shown to depend largely on the yarn linear density, the crimp value of yarns, under deformation, and the ratio of the two yarn curvilinear lengths in the structural repeat unit of the fabric. It is shown that there are considerable constraints imposed on the yarn curvature within the fabric, resulting in increased resistance to fabric stretching and bending compared to the results measured on yarns removed from the fabric. A study is made of the effect of yarn extensibility on the decrimping behavior of yarns unravelled from fabric. The effect of weave construction is prominent on the tensile behavior of fabric; its effect on the decrimping behavior of yarn and bending properties of fabrics is only marginal. The effect of blend composi tion on these mechanical properties has been examined for a series of wool/polyester woven fabrics produced from yarns of the same linear density and was found not to be significant.

The maximum fiber-packing density expected in electrostatic flocking or any process involving random impingement of fibers onto a substrate has been calculated using a Monte Carlo technique. This value was determined by generating random numbers to select the coordinates of points representing the location of fiber centers on a circular target, subject to the restriction that no two fibers overlap. The process was terminated after a specified number of trials failed to locate an unoccupied space large enough to accommodate an additional fiber. The fiber-packing density was then computed in terms of the number of fibers per unit area n and the fraction of total available space on the target occupied by fibers F. It is found that F is independent of fiber diameter and has a value of 0.531 with a standard deviation of 0.0038. This value (∼53% of available space occupied) is considerably less than the value of 90.7% expected for close-packed circles but much greater than those reported experimen tally.

The wettabilities of undrawn and drawn polyester filaments were measured in order to establish the influence of drawing on fiber surface properties. Advancing and receding wetting forces were measured using a technique for single filaments based on the Wilhelmy balance principle. The results indicate that the drawing process renders the filaments less wettable with respect to all four of the liquids used in this study (water, formamide, ethylene glycol, and hexadecane).

Useful properties are imparted to textile fabrics by regioselective derivatization without significantly impairing their quality. Woven cotton and wool fabrics and a woolen knit were brominated at the primary hydroxyl (C-6 and L-serine residue, respectively) with Hanessian's N-bromosuccinimide/triphenylphosphine reagent, giving a degree of substitution of 5% and 94%, respectively, for cotton and wool. Addition of sodium bromide to the reaction mixture did not enhance the bromine content of the product. The brominated textiles were of excellent quality and stability, and no odor was detected. 72% of the bromine incorporated into the wool was stable to five drycleaning cycles. Ten aqueous launderings removed all the bromine from the wool. The brominated fabrics exhibited a diminished flammability. The brominated wool was moth-resistant.

Air permeabilities for two woven fabric constructions having common warps but different filling yarns were measured. The filling yarns were produced by ring spinning, open-end spinning, core-wrapping with filament, and a no-twist process. Comparison of air permeabilities of the woven fabrics were made in the gray and bleached states. The effects of yarn structure, yarn twist, yarn crimp, and filament wrapping are discussed in relation to their effects on the air permeability of the two woven fabrics.

Solvent-crystallized, ground PET fibers were used in a gas chromatographic column as the stationary phase and subjected in situ to increasingly severe thermal treatment. After each treatment, an homologous series of hydrocarbons was passed through the column as molecular probes. After an initial reduction in surface sonption that was produced by heat treatment at 145°C, no further change was effected by heat, up to 175°C. Above 175°C, surface sorption decreased, while internal bulk partitioning increased, indicating marked internal changes of structure.