Undyed Fabrics Research Articles

Transfer of bacteria from fabrics to hands and other fabrics: development and application of a quantitative method using Staphylococcus aureus as a model.

To develop and apply a quantitative protocol for assessing the transfer of bacteria from bleached and undyed fabrics of 100% cotton and 50% cotton + 50% polyester (poly cotton) to fingerpads or other pieces of fabric. Test pieces of the fabrics were mounted on custom-made stainless steel carriers to give a surface area of 1 cm in diameter, and each piece seeded with about 10(5) cfu of Staphylococcus aureus from an overnight broth culture; the inoculum contained 5% fetal bovine serum as the soil load. Transfer from fabric to fabric was performed by direct contact using moist and dry fabrics. Transfers from fabrics to fingerpads of adult volunteers were tested using moist, dry and re-moistened pieces of the fabrics, with or without friction during the contact. Bacterial transfer from fabrics to moistened fingerpads was also studied. All the transfers were conducted under ambient conditions at an applied pressure of 0.2 kg cm(-2). After the transfer, the recipient fingerpads or fabric pieces were eluted, the eluates spread-plated, along with appropriate controls, on tryptic soy agar and the percentage transfer calculated after the incubation of the plates for 24 h at 37 degrees C. Bacterial transfer from moist donor fabrics using recipients with moisture was always higher than that to and from dry ones. Friction increased the level of transfer from fabrics to fingerpads by as much as fivefold. Bacterial transfer from poly cotton was consistently higher when compared with that from all-cotton material. The data generated should help in the development of better models to assess the role fabrics may play as vehicles for infectious agents. Also, the basic design of the reported methodology lends itself to work with other types of human pathogens.

Effect of Pressure Decatizing on Fabric Drape

The effect of pressure decatizing on the draping properties of wool suiting fabrics is investigated across a range of typical decatizing conditions. The study shows that fabric drape depends on fabric mechanical properties, decatizing conditions, and fabric history. Analysis of the drape of a range of pure wool suiting fabrics shows that the fabric drape coefficient depends more strongly on bending length than on shear rigidity, factors that are established through cloth construction. However the effect of pressure decatizing on the fabric drape coefficient is more closely associated with changes in shear rigidity rather than bending length. Pressure decatizing has more effect on the drape of undyed fabrics than dyed ones. The drape of dyed fabrics changes only slightly after pressure decatizing, but the drape coefficient of dyed fabrics is still less than undyed fabrics, even after pressure decatizing. These results are consistent with a model including setting (stress relaxation) and allowing for a change of yarn geometry during dyeing. Small increases in the shear rigidity of dyed fabrics after pressure decatizing are consistent with the effect of lateral pressure on the fabric during decatizing.

Dye Molecules as Bridges for Functional Modifications of Nylon: Antimicrobial Functions

Dye molecules often contain reactive groups such as sulfonate, amino, and hydroxyl that serve as auxochromes in dyes, but are chemically reactive and potentially useful as linkers for attaching functional moieties to synthetic fibers. Using these reactive groups as a means of functionalizing textile materials is proposed and implemented in this study of modifying chemically stable polymers. As an example of this innovative finishing tech nology, acid dyed nylon 66 and nylon 6 fabrics are finished in a quaternary ammonium salt solution, and durable and refreshable antimicrobial functions are conferred on the fibers. Most acid dyes can be used with this method to incorporate quaternary ammonium salts into nylon fabrics. The add-on levels of the salts on the dyed and undyed fabrics are significantly different, evidence for the occurrence of interactions of dye molecules with salts. Quantitative antimicrobial evaluations of the treated fabrics reveal that there are significant reductions in bacterial populations up on surface contact with the finished fabrics. The bactericidal function of the fabrics survives through ten Launder-Ometer washes, according to AATCC test method 61-1994, equivalent to fifty machine washes.

Influence of Direct and Reactive Dyes on the Enzymatic Hydrolysis of Cotton

Cotton fabric is subjected to enzymatic hydrolysis with cellulases before and after dyeing. The effects of direct dyes of increasing molecular size on the rate of the en zymatic hydrolysis reaction are investigated, along with mono- and bifunctional reac tive dyes with different functional groups. All reactive dyes studied and especially bifunctional reactive dyes, have a decelerating influence on enzymatic attack. The effect of the direct dyes depends strongly on the enzymatic treatment duration. Moisture regain values of enzyme treated fabric suggest a transient state of somewhat increased disorder of the cellulose structure at a specific stage of hydrolysis, which is alleviated by longer incubation times. At this stage, direct dyed fabric shows a hydrolysis rate approximately equal to or slightly higher than undyed fabric.

Relationship Between Tinctorial Depth and Fiber Fineness in Dyed Polyester Fabrics.

The influence of fiber fineness and fabric structure on the tinctorial depth of dyed polyester fabrics was investigated. Plain weave and stitch fabrics composed of polyester filament yarns with different single-fiber finenesses were prepared. The single filaments of the yarn used had finenesses of 0.4, 0.7, 1.0, 2.0, 3.0, and 5.0 denier. The fabrics were dyed with disperse dyes (C. I. Disperse Yellow 5, Red 72 and Blue 148) in various tinctorial depths. The relationship between dye uptake on fabrics (Cf) and K/S value in the Kubelka-Munk function was examined at various wavelengths. Plots of Cf vs. (K/S)d-(K/S)o give a straight line at a particular wavelength for each fabric dyed with the same dye, suffixes d and o refer to dyed and undyed fabrics, respectively. In the K/S region of 10 or less, where Kubelka-Munk function could be applied, the change in the tinctorial depth with Cf and fineness of fiber (D) is expressed by the following equation.This equation shows that a smaller denier leads to lower values for (K/S)d-(K/S)o, which in turn proves that the denier of a single fiber is a significant factor in making the tinctorial depth appear lighter. It was clarified that each fabric has a unique effective surface area and a light-scattering coefficient determined by the fineness of the single fibers and the weaving structure. It was confirmed that the light-scattering coefficient of an undyed fabric could be used to estimate the effect of the fiber substrate on the tinctorial depth.

EFFECT OF CRACKS ON THE PRESSURE-VELOCITY RELATIONSHIP OF AIR FORCED THROUGH BALED ALFALFA HAY

ABSTRACT Imperfections in lint cotton, particularly neps and seed-coat fragments, reduce processing efficiency in the textile mill and detract from appearance in yam and fabric. This study identified fiber properties and varieties which are consistently associated with low nep and seed-coat fragment levels in ginned lint, yam, and fabric. Growth conditions and maturity of the cottons were considered; the level of imperfections were measured in both dyed and undyed fabric. Correlations were determined and definite trends established between many of the variables. The information obtained will aid breeders in selecting for further development those cottons which have a low potential for imperfection formation during processing.

PROPENSITY OF COTTON VARIETIES TO NEPPINESS

ABSTRACT Imperfections in lint cotton, particularly neps and seed-coat fragments, reduce processing efficiency in the textile mill and detract from appearance in yam and fabric. This study identified fiber properties and varieties which are consistently associated with low nep and seed-coat fragment levels in ginned lint, yam, and fabric. Growth conditions and maturity of the cottons were considered; the level of imperfections were measured in both dyed and undyed fabric. Correlations were determined and definite trends established between many of the variables. The information obtained will aid breeders in selecting for further development those cottons which have a low potential for imperfection formation during processing.

Damage to Undyed Polymeric Substrates Caused by Weathering

Abstract This work concerns the damage to undyed fabrics caused by climatic conditions prevailing at an urban site in Egypt. Samples of unfinished cotton of different counts and densities were used. For comparison purposes, samples of nylon, polyester, taffeta and satin fabrics were included in the survey. These were subjected to unprotected outdoor exposure for 120 days. The different fibres showed significant variations in changes to physical properties arising from exposure. Thus, breaking strength losses range from 29 to 87% of the original value, while losses in elongation range from 26 to 85% of the initial elongation value. Losses were found to be least for the coarsest cotton fibre and highest for taffeta and satin. Nylon and polyester were both seriously attacked. With these a much greater loss of strength than of elongation was observed.

Effect of temperature factors on the optical properties of undyed fabrics

Effect of temperature factors on the optical properties of undyed fabrics

EVALUATION OF SELECTED BLEACHING TREATMENTS SUITABLE FOR HISTORIC WHITE COTTONS

Naturally yellowed, historic, undyed cotton fabric was bleached by selected methods to determine whitening effectiveness and extent of physical and chemical degradation. Evaluated were samples chemically bleached with hydrogen peroxide bleach solutions at concentrations of 0·3 and 0·6% and oxidized for , 1, and 3 hours; and samples sun-bleached in natural light for 4, 16, and 32 hours. Whiteness Index values were greatest for the chemically bleached samples oxidized for 3 hours and for the sun-bleached samples exposed to sunlight for 32 hours. Physical and chemical degradation, assessed by breaking strength, methylene blue, and copper number tests, revealed that no significant changes in the physical or chemical properties of the cotton samples resulted from the various bleaching treatments.

The Horizontal Flame-Propagation Rate of Undyed Cotton Fabrics

Differentiation of the flammabilities of nonflame-retardant, all-cotton fabrics cannot be accomplished by the usual test procedures, as these merely provide the means for determining when a fabric exceeds a certain set standard. The desired differentiation, however, can be obtained by measurement of the flame-propagation rate using the Ahiba Flammability Tester with the sample in the horizontal position. Eight nonflame-retardant, undyed cotton fabrics of different constructions were studied. The weights of the fabrics fell into four groups: 3.1, 3.6–3.8, 4.1–4.4, and 7.5 oz/yd2. Specimens were cut from the warp and filling directions of the fabrics; one set of specimens was oven-dried prior to testing, while another set was conditioned to equilibrium moisture content at 65% relative humidity and 70°F. Burning was different in the warp and filling directions. Differences in flame-propagation rates were found that were not weight dependent. In general, flame-propagation rate was not constant over the length of the specimen; in the warp direction the rates increased with distance from point of ignition, while in the filling direction constant and decreasing rates were also found. Flame-propagation rate was not effected to the extent expected by changing from oven drying to conditioning to equilibrium moisture content; only four of the eight fabrics showed significant changes. Burning in the filling directions of two fabrics was markedly changed; smaller differences were found in the warp direction only of a third fabric and in both the warp and filling directions of a fourth fabric.

The Effect of Dyes on the Flammability of Cotton Fabric. 1

A study has been initiated of the effect of dyes on the flammability of cotton fabric. The initial phase reported here concerns the effects of dyes alone on all-cotton fabric, with representative dyes being selected from the reactive, sulfur, vat, ingrain, direct, and acid classes and from the fluorescent brightening agents. The level of Rammability of the dyed fahrics was measured by the oxygen index technique; thermal degradation in a nitrogen atmosphere was followed by thermogravimetric analysis. Many of the dyes increased oxygen index over that of the undyed fabric. Dyes also markedly influenced the path of thermal degradation.

Weathering Durability of Cotton Fabrics Treated with APO-THPC Flame Retardant

The influence of APO/THPC mole ratio on durability of flame retarclancy, resin retention, and strength retention of treated cotton fabric was determined by means of natural and artificial weathering tests. In both types of weathering, the use of photo active dyes as a means of accelerating the tests was studied. APO/THPC mole ratios of 2 : 1-8; 1 gave greater durability of APO-THPC resin and flame retardancy than did the standard I : 1 ratio. Photoactive dyes accelerated outdoor weathering by as much as fivefold, without obscuring the effect of mole ratio on resin durability. Predyeing was more effective than afterdyeing in causing accelerated weathering. Increased APO/ THPC mole ratios also gave increased breaking strength retention during weathering of undyed fabric, but produced no improvement on dyed fabric. These effects also occurred in Weather-Ometer tests made in the presence and absence of photoactive dyes. The APO-Zn(BF4)2 flame-resistant, wash-wear finish showed improved weathering durability comparable to that obtained from high-mole ratios 'of APO/THPC. The chlorine content of APO-THPC-treated fabric was 81% to 96% of theory at all mole ratios of APO THPC, indicating at least two modes of copolymer formation. The rate at which phosphorus was lost from APO-THPC during weathering was generally equal to the rate of nitrogen loss, expressed in percentage losses/time. The APO-Zn(BF 4)2 finish lost phosphorus more rapidly than nitrogen, indicating a different mode of resin breakdown.

Colour Fastness to Dry‐cleaning

The effectiveness of various methods that have been proposed for the assessment of colour fastness to dry‐cleaning has been evaluated by comparison with the effects of actual dry‐cleaning on a wide range of dyed and printed textiles. None of the existing tests was considered to be entirely satisfactory. The main cause of their inadequacy was a failure to reproduce the mechanical effects in a commercial dry‐cleaning process. A new method is proposed in which the specimen is placed inside a cotton bag along with steel discs and shaken in 200 ml of perchloroethylene at 30°C for 30 min. This method has provided a realistic prediction of the effects of commercial dry‐cleaning and it has shown good reproducibility in interlaboratory trials. The use of undyed fabrics to assess staining can give misleading results and it is considered preferable to rely upon an assessment of the discoloration of the solvent at the end of the test to indicate a lack of fastness of the material that could lead to staining.

Effect of Light upon Wool

It is shown that comparative diffuse reflectance measured simultaneously on test and control specimens with a recording spectrophotometer affords a sensitive measure of color changes by light in undyed wool fabrics, especially of the “orange dip” caused by ultraviolet at 254 m μ. For this purpose comparative reflectance was found to be much more sensitive than absolute or relative reflectance or than comparative or simple transmittance. Transmittance in an immersion liquid, o-dichlorobenzene, was the least sensitive. An expression for calculating transmission from reflectance values is derived and applied. Optical properties of three fabrics are compared for the above uv and visible region.

Publications Sponsored By The Society's Fastness Tests Co‐Ordinating Committee—XXVI The Measurement of Colour Fastness to Steam Pleating

The Pleating Fastness Subcommittee has studied the problem of testing the fastness of coloured textiles to steam pleating processes and has devised a suitable test method. There is good correlation between the results of the test and those produced in practical pleating. A simple piece of apparatus has been designed to maintain close and even contact between the test pattern and adjacent undyed fabrics. Any staining of these adjacent fabrics takes place uniformly, and reliable assessment of the degree of staining can be made. A range of steaming conditions has been chosen to cover all fibres. The test has been adopted as an I.S.O. Tentative Test, the only modification being the addition of two extra steaming conditions.

5—Light Transmission and Air Flow through Nylon Parachute Fabrics

Photoelectric techniques have previously been employed in the study of yarns and fabrics1,2. In the work here described. a photoelectric device was used to examine nylon parachute fabrics for variations of open area. Both dyed and undyed fabrics were tested so that allowance could be made for filament translucency. By selecting fabrics of varying porosity, the dependence of air flow on open area was investigated, particularly in respect of variations across the width of the fabric. The conclusions reached were confirmed by means of the bubble-pressure3 method.

Improved Weather Resistance by Acetylating Vat-Dyed Cotton

Cotton has been made unusually resistant to degradation by weather by first dyeing it with certain light-stable vat dyes and following this with partial acetylation. Vat dyeing alone or partial acetylation alone do not make cotton significantly more resistant to deterioration by sunlight than undyed fabrics, except for a few colors which do have a protective effect. However, when these two processes are combined, excellent re sistance to solar radiation is added to the excellent mildew- and rot-resistance of partially acetylated cotton. Data were obtained on a number of individual vat-dyed and vat-dyed and acetylated cotton materials that had been exposed to outdoor weathering. From the results of these tests, it is estimated that the combination of vat dyeing with light fast colors and acetylating may more than double the outdoor service life compared to cotton vat dyed only, or acetylated only, with somewhat better color retention when the cotton has been both dyed and acetylated.