Textile Research Journal

An investigation determined the feasibility of detecting and quantitating commer cially applied agents on wool by pyrolysis gas chromatography. Characteristic peaks were generated from benzoylated wool, from wool treated with the insect-resist agent Mitin FF and from wool dyed with Lissamine yellow 2G, thus demonstrating that the technique is suitable for detecting the presence of such agents. Two approaches were used for the quantitative analysis of the treatment and the dyeing using the data from the resulting pyrograms. One approach used peak area response per microgram of treated wool and the other used peaks generated from wool's tyrosine as internal standards. Although the latter approach gave a better linear fit, inverse regression analysis demonstrated that the former approach was most suitable for predicting agent add-on (percent on weight of fiber).

In a series of studies on the relation between the wettability or repellency of textile assemblies and their structures, apparent contact angles (ϕ) of monofilament nylon and polyester mesh screens to water were measured to clarify the effect of the woven structure on the repellency of textiles. The apparent equilibrium contact angles (ϕ _e ), not the apparent advancing ones (ϕ _A ), can be quantitatively predicted by using the theoretical expressions for the liquid-solid and liquid-air interfaces per unit of mac roscopic surface area in the Cassie-Baxter equation (f ₁ and f ₂, respectively) and the true advancing contact angles (θ _A ). The effect of the size of sessile water drops on the apparent contact angles (ϕ) was also interpreted in terms of the distortion of the drop surface owing to the gravity effect.

Cotton print cloth containing both immature fiber neps and process neps composed of torn and ruptured mature fibers was treated with mercerizing and submercerizing strength sodium hydroxide and with liquid ammonia. Scanning electron microscopic examination of mercerized samples showed separation of the nep mass and swelling of individual fibers in both types of neps. Treatment with submercerization strength sodium hydroxide resulted in swelling of surface fibers of the nep but retention of much of the overall fiber compactness. Liquid ammonia appeared to have little effect on the swelling of the individual immature fibers, but did achieve a separation of the compact nep mass. After dyeing with each of ten direct dyes, the mercerized samples showed an average increase in visible coverage of neps of 95%, while the dyed sub- mercerized samples showed an average increase in nep coverage of 86%. After liquid ammonia treatment, significant improvement in nep coverage occurred with five of the ten dyes examined.

The work of earlier papers in this series is extended by quantifying the level of wool fabric ageing that occurs in actual garment wear. The main experimental variables considered in this paper are the ageing history of the fabric, the time of wear, the level of physical activity attributed to the subject wearers, and the position of the fabric test sample on a pair of trousers worn by each subject wearer, that is, the lap , crutch, behind the knee, and the cuff. Fabric ageing is evaluated from bending stress relaxation measurements made on the fabric test samples subjected to two sets of ambient con ditions : constant temperature and relative humidity (20°C, 65% RH), and conditions of changing relative humidity at constant temperature. The fabric stress relaxation rate is always higher for fabrics after wear than the corresponding control fabric sample, which was merely allowed to age for the same time but was not subjected to any wear. Significant differences in fabric bending stress relaxation rates under both constant and changing humidity conditions occur as a result of different levels of subject wearer activity. The fabric bending stress relaxation rate for an initially aged fabric that has been worn for an average of 1.5 days is equivalent to one of the standard de-ageing treatments [2] used in fabric wrinkle testing.

Four potential primary standards for formaldehyde were evaluated as replacements for the formalin usually used with colorimetric reagents in analyzing textiles for form aldehyde. Of the four—sodium formaldehyde bisulfite, hexamethylenetetramine, tet raoxane, and 1,3,—dioxolane—only 1,3,-dioxolane yielded the stoichiometric amount of formaldehyde under relatively mild conditions of hydrolysis. 1,3,-Dioxolane can be hydrolyzed in 6N HCl for four hours to produce one mole of formaldehyde per mole of 1,3,-dioxolane. Stabilities of standard formaldehyde solutions from 1,3,-diox olane were compared with those from formalin, and there is a discussion of 1,3, dioxolane-based formaldehyde solutions used to prepare calibration curves of several colorimetric reagents for formaldehyde.

Assessing dark fiber concentration in mill batches of top destined for the white and pastel trade is a problem of major economic importance in the wool industry. Thus it would seem desirable, if not essential, to have an agreed set of procedures for de termining whether a given concentration is exceeded. The decision criteria used throughout the industry vary widely, however, due in part to the lack of an underlying rationale. In this paper a framework is proposed within which a broad class of decision schemes may be constructed. The objective is to provide a rational basis for industry- wide uniform procedures. A method is then described for comparing the performance of a given scheme, from within this framework, with an "ideal" performance. Also a procedure for determining the parameters of such a scheme is outlined. The parameters of several example schemes are calculated and an example given of how one such scheme might be chosen as an industry standard.

A nonsteady-state cooling method has been used to measure the thermal diffusivity (α) of nonwovens. The method is relatively simple and requires a minimum of spe cialized equipment. The calculations required to obtain α from cooling curves are somewhat involved but can be easily performed on a small computer. The apparatus allows α to be measured at various degrees of sample compression. Thermal conduc tivity can be obtained from α if heat capacity and bulk density are known. The tech nique was used to study the effect of fiber structural parameters on the conductivity of nonwovens. The results indicate that in agreement with established theory, con ductivity decreases if the nonwoven is compressed or is made with finer fabrics or has a reflective coating on the fiber surface. This occurs because of a reduction in the radiative component of heat transfer. Fiber shape has no effect on thermal conductivity. Nonwovens made with experimental hollow fibers have lower thermal conductivity than nonwovens containing solid fibers of the same size; no explanation is currently available for this phenomenon.

Damage caused to wool in the carbonizing process can be assessed by methods such as alkali solubility or by determining the loss in tensile strength of the yarns and fabrics so produced. These tests are reliable and reproducible, but they are time consuming and provide a result some five or more hours after the process is complete. It is then too late to adjust the process variables so as to minimize the damage to the wool. A rapid and sensitive test is described, which is based on the ninhydrin reaction with peptides and is able to measure the damage within only 10 minutes of sampling the carbonized wool immediately after baking. The results correlate well with both alkali solubility and tensile strength test methods. The new test procedure allows for the possibility of an "on-line" method of controlling damage in the wool carbonizing process.

A rapid cotton conditioning apparatus that uses a combination of dry air and room air forced through a blended 10 gram laboratory sample is evaluated with 14 cottons. The evaluation indicates that a 6 to 10 minute conditioning cycle is equal to 24 to 48 hours of room conditioning in trays. The use of dry air in the rapid conditioner had little or no effect on hysteresis when compared to samples that were room conditioned in trays.

The weaving performance of a yam is mostly decided by its grey yam properties and the treatment it receives in the processes subsequent to spinning. This paper presents a study of the effect of the magnitude of yam faults (length and cross section) and of sizing on their performance in weaving. The results showed that particularly C₃, C₄, and all D Classimat faults, even after sizing, have lower strength, elongation, and abrasion resistance. The presence of these faults introduces a very high frequency of low strength, elongation, and abrasion threads into the yam, which in turn are prominent sources of warp breaks. When subjected to tensile load, most yams broke at or in the vicinity of a fault. The frequency of such yarn breakages increased with fault length and cross section.