Tyrone L. Vigo

Temperature Adaptable Hollow Fibers Containing Polyethylene Glycols

Polyethylene glycols (PEGs with average molecular weights of 400, 600, 1,000 and 3,350) incorporated as 57% aq. solutions into hollow rayon and polypropylene fibers, after drying and conditioning, produced heat contents (Q) 1.2-2.5 times greater than untreated hollow polypropylene and 2.2-4.4 times greater than untreated hollow rayon fibers. The resultant Q values in a given temperature interval were reproducible for at least 50 heating and cooling cycles with no adverse change in their thermal performance compared to their first heating and cooling cycle. As monitored by differential scanning calorimetry, these modified fibers had thermal storage and release values useful at tempratures as low at -8 to -48°C on cooling and as high as +42 to +77°C on heating, with little variability in Q values within the same fiber or between different batches of the same fiber containing a particular polyethylene glycol.

Antibacterial Fiber Treatments and Disinfection1

Developments and research in the present decade on the antibacterial finishing and disinfection of textiles are reviewed. Definitions and concepts of terms such as antimicrobial agent, antibacterial agent, disinfectant, and sanitizers are discussed from both a regulatory and scientific perspective. Quantitative tests for determining antibacterial activity of textiles usually involve sterilization of fabric, inoculation with a microorganism, and determination of bacteria remaining by wash-recovery or colony-count under a low-power microscope. Most qualitative tests for antibacterial activity are based on the ability of the agent to diffuse off the fiber into an agar medium. Most antifungal tests consist of inoculation of fabric, then inspection for visual growth of fungi after varying periods of time. Microbial ecology of the skin-clothing interface differs in everyday environments and situations from environments conducive to growth of microorganisms and cross- infection ; predominant bacteria and fungi and microbial population on different parts of the body are discussed in this context. Microorganism persistence on textiles is influenced to some extent by fiber type. Recent studies show that synthetics retain more odor-causing bacteria, and that dermatophytic fungi are more persistent on synthetics than on natural fibers; persistence time of pathogenic bacteria,on natural and synthetic fibers is dependent on relative humidity and method of fabric contami nation. Newer and commercialized processes for producing antibacterial fabrics durable to laundering are evaluated, and frequently-used disinfectants and sanitizers for textiles are stressed. Various techniques for affixing such agents to fibers are listed, and requirements for producing effective antibacterial and antifungal fibers for particular end-uses are enumerated. Some novel and recent uses for antibacterial fibers, such as water disinfection and air purification, are also mentioned.

Chlorination and phosphorylation of cotton cellulose by reaction with phosphoryl chloride in N,N-dimethylformamide

Abstract Native cotton yarn reacts rapidly with phosphoryl chloride in N,N-dimethylformamide to produce highly chlorinated cellulose (degree of substitution of 0.5 or greater), phosphorylated cellulose, and cellulose formate. The ratio of chlorination to phosphorylation was readily controlled by varying the concentration of phosphoryl chloride in N,N-dimethylformamide. Reaction variables studied were the reagent concentration, reaction temperature, and reaction time. The effect that each of these variables has on the tensile and flammability properties of the resultant yarns was investigated. Yarns containing large proportions of chlorine have high tensile-strength and are unusually extensible, whereas yarns containing phosphorus have high flame-resistance. A mechanism for the selective chlorination or phosphorylation of the cotton cellulose is advanced.

Applications of the Trace Gas Technique in Clothing Comfort

A laboratory appartus employing a trace gas technique has been developed to systematically study the effects of fabric and garment properties on microclimate ventilation in a simulated garment assembly. Nitrogen was used to flush the microcli mate enclosure, and the rate of atmospheric oxygen build-up in the system was traced. The gas exchange was assumed to have first-order kinetics. A new parameter, areal ventilation rate, that takes into account the microclimate volume and the fabric surface area, has been developed. External wind effects were simulated by conducting experiments in still air and in the presence of forced air flow. The results show that in still air, fabric air permeability has an insignificant effect on areal ventilation rate. However, with increasing external air flow, the effect of air permeability becomes more pronounced. Areal ventilation values are found to increase linearly with increasing external air velocities, and the influence of fabric constructional variables increase accordingly. The combined effects of permeability and air velocity on areal ventilation rate are interpreted in terms of a previously derived empirical equation. Simulation of garment openings did not have a significant effect on the ventilation rate, illustrating that small air passages are of less significance than flow through the fabric itself.

Temperature-adaptable fibers containing substances with solid—solid transitions

Abstract Incorporation of 50% aqueous solutions of compounds (exhibiting high Δ H values due to solid—solid transitions prior to melting or crystallization) into hollow fibers or treatment of conventional fibers with these solutions, produced after drying and conditioning, modified fibers with 2–4 times the heat content ( Q ) of the corresponding untreated fibers in a given temperature interval. Of the compounds evaluated, 2,2-dimethyl-1,3-propanediol and 2-hydroxymethyl-2-methyl-1,3-propanediol produced the most reliable and reproducible thermal effects in the modified fibers that lasted through 50 heating and cooling cycles. Of the treated fibers, hollow rayon was the most effective, followed by cotton, then hollow polypropylene relative to the corresponding untreated fibers. As monitored by differential scanning calorimetry, these modified fibers had thermal storage and release values useful at temperatures as high as 72–102°C on heating and as low as 37-7°C on cooling, with generally little variability in their Q values within the same fiber or between different batches of the same fiber. Other compounds of this type were not effective for use with the fibers due to sublimation/high vapor pressure characteristics (2,2-dimethyl-1-propanol and pentaerythritol) or because of their anomalous and inconsistent thermal behavior (2-amino-2-methyl-1,3-propanediol).

Permeability of Soil-Geotextile Systems

A specially designed laboratory-type permeameter was used to characterize liquid flow behavior through various combinations of soils and geotextile fabrics subject to different flow rates and hydrostatic pressures of water. Spunbonded geotextiles made from two different fiber types (e.g., polyester and polypropylene) were selected for the study. Volume flow rates were varied up to 21 cm/second by adjusting hydrostatic pressure differences from 2.5 to 76.2 cm. The results suggest single layer barriers of the geotextiles alone have small effects on flow rates of water, but sand-geotextile combinations exhibited strikingly different behavior. In prewashed soil-geotextile combinations, the permeability decreased non linearly with increasing depth of soil above the fabrics, independent of the supporting fabric. For soils that were not prewashed, however, fine particles in suspension settled at the soil-water interface to produce an almost impervious layer or cake structure. This caking was a function of time and became the controlling factor of flow throughout the composite. High clogging in even thin fabrics was observed when sand was replaced by fine material such as Kaolite. The behavior was different than that of the fine material in unwashed sand. In addition, geotextile fabrics showed low resiliency to recovery from cyclic compression. The practical interpretation of this is that the porosity of the fabric may decrease significantly with time if incorporated into structures that are subject to compressive forces.

Preparation of fibrous cellulose formate by the action of thionyl chloride in N,N-dimethylformamide

Abstract Cotton cellulose yarn, either in the untreated state, or altered by swelling pretreatments involving mercerization or solvent-exchange, or both, reacts readily with solutions of thionyl chloride in N , N -dimethylformamide at room temperature. Subsequent hydrolysis produces cellulose formate as the major product; this derivative is presumably formed via reaction of the cellulose with the iminium salt, and a chlorodeoxycellulose. The reaction variables studied were the effect of ( a ) preswelling the cellulose in N , N -dimethylformamide, ( b ) the reaction time, ( c ) the concentration of thionyl chloride, and ( d ) the moisture content of the cotton prior to preswelling and reaction. The effect of various pretreatments on the type and rate of reaction which the cotton undergoes was also determined. The stability of the formyl group and of the sulfurous acid monoester group to hot water and to dilute ammonium hydroxide, as well as the tensile properties of yarns treated with thionyl chloride and N , N -dimethylformamide, were investigated.

Sorption of Air Pollutants onto Textiles

A review of research reported in the literature on the sorption of SO2 onto textiles and related materials is presented. The detrimental effects of pollutants on the me chanical and aesthetic properties of textiles have been well documented and are also briefly noted; however, there is a consistent lack of data on the rate and extent of sorption of air pollutants onto textiles. Sorption rates, expressed as deposition ve locities (ν g ), are affected by the environmental chamber used for exposure. There are differences in sorption that may be attributed to fiber type and also to the geometry of the textile structure (i.e., fiber, yarn, fabric) on exposure. These factors, however, have not been systematically assessed and although the process of sorption by polymer films has been examined, the corresponding mechanisms of sorption/desorption phe nomena for textile structures have not been elucidated. The literature reviewed also shows that most studies of fibers have been primarily concerned with the sorption behavior of wool.

Facile preparation of deoxy(thiocyanato)celluloses

Abstract Deoxy(thiocyanato)celluloses were prepared by treating chlorodeoxycellulose fabrics with potassium thiocyanate in N,N -dimethylformamide. Under optimal reaction-conditions, more than 80% of the chlorine atoms in the cellulose derivative were replaced by thiocyanate groups. Both the chlorodeoxy- and deoxy(thiocyanato)cellulose fabrics exhibited moderate antibacterial activities. Variables studied were thiocyanate concentration, reaction time and temperature, and degree of substitution of the chlorodeoxycellulose in the fabrics being treated. The effect that each of these variables had on the replacement of chlorine atoms by thiocyanate groups was investigated. The tensile, wrinkle-recovery, and biocidal properties of the chlorodeoxy- and deoxy(thiocyanato)cellulose fabrics were also compared.

Preparation of fibrous cellulose 2,2,2-trichloroacetimidate

Abstract Cotton cellulose pretreated with alkali-metal hydroxides reacts with trichloroacetonitrile at room temperature to give cellulose 2,2,2-trichloroacetimidate, a new type of cellulose derivative. Cellulose trichloroacetate is also formed, but this is readily hydrolyzed under mild conditions. Elemental analysis and infrared spectra correlate well with the selective hydrolysis. Higher degrees of substitution are obtained by using equimolar amounts of cellulose and hydroxide ion, and they increase with increasing concentration of the nitrile. The tensile properties of the modified cellulose, both before and after hydrolysis, are described.