William K. Walsh

Mechanisms of Transient Moisture Transport Between Fabrics

A technique was developed to study moisture transport and to determine the mechanism by which moisture is transported between fabrics under transient conditions at low moisture contents. A variety of fabrics were tested and experiments were performed at various levels of moisture content from 3% to over 100% above regain. Vapor diffusion was the major mechanism of moisture transport between two layers of fabric at low moisture levels for all fabrics. Wicking did not begin until the moisture content was high, more than 30% above regain for the woven samples. The knitted samples did not wick at all. Hydrophilic finished polyester samples had markedly improved transport rates at high moisture contents but showed no improvements at low levels of moisture where vapor diffusion prevails. Moisture transport appears to be closely related to comfort. At low moisture levels, fabrics rated as comfortable transported more moisture than fabrics rated as uncom fortable. Polyester fabric to which a hydrophilic finish was applied to improve moisture transport by wicking was judged similar in comfort to the unfinished polyester. Both transport little moisture at low levels of moisture content, perhaps because at low levels of moisture content, wicking cannot occur, since there is an insufficient amount of moisture to fill the capillaries to permit wicking.

Delayed Cure With Ionizing Radiation1

The use of ionizing radiation as the delayed step in a durable-press process has been investigated. Methylol acryl article is reacted monofunctionally with cotton by a pad- dry-cure procedure, using acid catalysis. The fabric is washed free of all unreacted chemicals, made into garments, and cross-linked at room temperature with β rays 2 from a machine irradiator. The machine used in the experiments is capable of finishing up to 8,000 pairs of slacks in an 8-hr shift.

The Cross-Linking of Cotton With Vinyl Monomers Using Radiation and Chemical Catalysis1

The work presented here is the result of a series of experiments attempting to cross-link cotton by using difunctional monomers having at least one vinyl group. Emphasis was placed on the delayed cure aspects of these monomers. Chemical reaction of the monomers was initiated both by ionizing radiation and by a conventional. chemical free-radical catalyst.

The Effect of the Glass-Transition Temperature of Conventional and Radiation-Deposited Polymeric Additives on Mechanical Properties of Cotton Fabric

The change in properties of cotton fabric produced by polymeric additives with varying degrees of stiffness or softness has been investigated by measuring these properties at different temperatures. It was concluded that changes in crease-recovery angle produced by these polymers were not due to lubrication but were related to the elastic-recovery properties of the added polymer. Changes in tear strength and abrasion resistance were shown to be a function of interyarn mobility by measuring yarn withdrawal forces of the fabrics. Radiation-induced deposition of polymers produced changes that were qualitatively similar to those made by conventional polymer applications, but the changes were not as pronounced. This was attributed to the lower degree of surface deposition and the lack of cross-linking of the radiation deposited polymers.

Radiation-Induced Addition of Flame Retardants to the Double Bond in Acrylamidomethyl Cellulose

Cotton and rayon fabrics were condensed with N-methylol acrylamide to give products with various degrees of un saturation. Radiation-induced free-radical addition to the double bonds in these fabrics was accomplished with carbon tetrachloride, bromoform, chloroform, bromotetrachloromethane, polyethylene oxide, chloral and bromal hydrate, and sodium hypophosphite. Stannous and stannic chloride were also reacted by what seems to be a different mechanism. Bromination of these fabrics is also described. Significant flame retardancy was obtained without alteration of hand, because the reactions are limited to the inside of the cellulose fiber.

Radiation processes for textiles

The possibilities of using radiation as a catalyst for chemical reactions on textiles has intrigued researchers in this field for more than fifteen years, but practical applications have been elusive. The use of isotopes for radiation sources in the early part of this period was the primary limitation, but much interesting and useful work was carried out. This information has been expertly reviewed by Gilbert and Stannett (i) and Rutherford (2). The introduction of high intensity electron accelerators in the mid-sixties led to a further increase in interest and one commercial process for permanent press (Deering Millikens). Another barrier appeared, however, in the lack of chemicals available that were suitable for high rates of polymerization. The research on textile radiation processes in the late sixties and early seventies relied almost completely on the versatile N-methylol acrylamide, which has a high polymerization rate constant, gives gel on polymerization, and has cellulose reactivity through the methylol group.

Radiation curing of pigment prints on textiles

Abstract Printing fabrics with mixtures of pigment, difunctional oligomers, and monomers and curing with ultraviolet or electron beam radiation saves between 3000 and 5000 BTUs per pound of fabric compared to conventional techniques using pigments, latex binders and aqueous acrylic or solvent emulsion thickeners. Elimination of the energy needed to evaporate the water and solvents and cure the binder accounts for the savings, but the subsequent reduction in print paste volume causes problems in application. Adjustments in paste rheology, reductions in application roller engraving depth, and increasing paste volume by foaming help to solve this problem. Paste formulation changes affect radiation curability, fabric stiffness, print quality and color fastness. Interactions between all these parameters is discussed.

Electron-Beam-Initiated Grafting of Flame Retardants to Fabrics Containing Cellulose. I. Reaction Rate Studies

Abstract Triallyl phosphate (I), bis(β-chloroethyl) vinyl phosphonate (II), and a multi-functional condensate of n were grafted to cotton and rayon fabrics and the grafted products screened for potential flame retardancy. Grafting was initiated by a 48 × 6 in. electron beam, in air, from a 550 kV, 20 mA accelerator powered by an insulated core transformer, with a dose rate of approximately 1 Mrad/sec. The monomers were either copolymerized in untreated fabric with N-methylol acrylamide as a coreactant or were copolymerized with pendant double bonds in fabric that had been acrylamidomethylated in a prior step.

Electron Beam Fixation of a Flame Retardant Applied Without Water by Coating Methods Fabric Properties and Bilateral Distribution of the Flame Retardant in the Cotton Fibers

Low wet pickup and high solids finishing techniques can produce fabric with the resin distributed in a variety of ways. depending on the method used. Liquid Fyrol 76®, applied to cotton fabric by a number of different procedures, and polymerized at room temperature with electron beam, gave resin distribution that varied from quite nonuniform at low application pressures to complete uniformity at high pressures, even to the point of lumen and fiber penetration. Small amounts of water (as low as 7% above regain) before application effected a uniform distribution even at low pressure.

Activation Analysis in Textile Processing

The use of neutron activation analysis as an analytical tool in textile processing is discussed. Gamma-ray spectra of activated fibers show the presence of many trace elements, but are not distinctive enough individually to allow identification of the fibers by the spectra. It is demonstrated that elements that lend themselves to neutron activa tion may be used as tracers in fiber process studies. Activation analysis may also be used successfully as a method for the analysis of yarns and fabrics for additives, such as sizes and finishes.