Textile Research Journal

Traditional anionic dyeing of cotton requires large amounts of salt to assist dye sorption. This paper reports a method of using trimethylolmelamine (TMM), a com mon durable press finish, to treat cotton for dyeing. TMM pretreated cotton has re markably improved affinity for anionic dyes and no longer needs the assistance of salt in the dyebath. Furthermore, effluents from such processes contain much less dye than effluents from ordinary salt-assisted dyeings. This technology not only increases the efficiency of dyeing without salt, it also considerably decreases the burden of effluent treatment. By this method, cotton can also be dyed with acid dyes.

Shrink-resistant properties and surface characteristics were investigated for wool fibers treated with hydrophilic multifunctional epoxides (glycerol polyglycidyl ether—GPE). Two different reaction conditions were used for the treatment, one in a saturated NaCl aqueous solution (S sample ) and the other in the absence of NaCl (W sample). Add- on percentages of both samples were almost the same. On the other hand, both shrink- resistant properties and surface characteristics were different for these two samples, showing that the reaction medium strongly affected the reaction mode of GPE. The degree of shrink-resistance of the W sample did not improve, while that of the S sample was much improved and almost equal to Cl/Hercostt (commercially) treated wool fibers. FTIR analyses showed that the surface concentration of GPE in the S sample was lower than that in the W sample, reflecting that the hydrophobic nature of the scale surface was maintained for the S sample and not the W sample. SEM observation results revealed prominent scale edges for the W sample but not for the S sample. These results explain the differences in shrink-resistant properties for the two samples.

A qualitative nondestructive technique for fiber identification was developed using near infrared (NIR) spectroscopy. A neural network was trained to identify 17 different fiber types using the NIR absorbance spectra from a library of 390 samples. The neural network model was verified by testing untrained samples. It was not only able to identify single fibers, but was also able to correctly identify blends of fibers from fabrics for which it had not been trained.

The dynamics of the drafting process for cotton sliver is investigated with regard to its principal role in the synthesis and optimization of automatic control systems for reducing sliver irregularities. The approach is formal: the models refer to spectral filters, and the parameters of the respective transfer functions are determined by ad ditional signals—the speeds of the drafter rollers. Considering some trivial initial con ditions as given and using integral transformations of known initial equations, math ematical models in the form of transfer functions are obtained for a double-zone drafter with fibers of equal or different lengths. The drafter is presented as an object with four inputs and one output. The models are also presented in digital form as discrete transfer functions. To estimate model parameters, on-site experiments with harmonic test signals follow standard identification procedures. Time series with values of the object main signals have been registered synchronously using a digital data acquisition system with minimal sampling period. A specially designed software pack age is used to simulate process dynamics and the parts of the control system.

In Parts I and II, we reported that during nonsteady-state transport of water vapor through layered fabrics, the temperature between two fabrics rose. In this study, we measure the surface temperature of the first-layer fabrics in similar experiments. The mass of the first layer is changed by tightly stacking the same fabrics, and the surface temperature rise is measured as a function of the mass and the kind of polymers. The rise of surface temperature is proportional to the mass of fabrics and the water ab sorption characteristics of the polymers. We can confirm that the temperature rise that occurs in the space between layered fabrics is mainly due to the heat of absorption of water vapor by the polymers (fabrics).

The correlation between wetting properties and water absorbency was investigated for cellulosic and polyester fabrics soiled with various oily substances. As a measure of the wettability of oil, the work of adhesion between oil and water was estimated from surface and interfacial tension data. Water contact angles against the oily soiled cellophane and polyester films were measured to examine the wettability of the soiled surface. These wetting data were plotted against the water absorbency of the rayon and polyester fabrics soiled with oil. The results show good correlation between the wettability of oil or of the oily soiled surface and the liquid water uptake of the fabrics. However, the differences between the geometric structures of the fabrics and plain surfaces must be considered in further discussions.

Low stress tensile properties as measured by KESF instruments—hygral expansion, relaxation shrinkage, and the crimp of the yarns in a fabric—were determined for a pure wool fabric after each of a number of dyeing and finishing processes. The dyeing recipes and dyes cover the range for wool in industry. Dye-fiber interactions were evaluated by comparing the properties of dyed fabrics with those of blank dyed controls. Dyeing and finishing alter many mechanical and physical properties of a fabric by changing the crimp of its yams, due to stress relaxation of interyarn forces in the unfinished fabrics during processing. The degree to which the initial interyarn stresses are relaxed is also an important parameter. Acid and chrome dyes did not affect the resulting fabric properties, but reactive dyes often had a dramatic effect on changes that took place during piece dyeing. Reactive dye-fiber interactions altered fabric crimp as a result of dyeing. In turn, crimp differences affected the resulting crimp-dependent fabric properties—hygral expansion and low-stress tensile properties. The effect was resistant to decatizing. This result has beneficial implications for controlling hygral expansion.

Fabric surface irregularities are measured using a novel attachment to a constant rate of elongation tester. The number of peaks and amplitude of the stick-slip traces correspond to the number and height of surface asperities on fabrics, respectively. Fabrics that yield more peaks and lower amplitude pulses are judged smoother than those with fewer peaks and higher amplitudes.

The influence of the molecular structure of reactive auxiliaries was investigated with respect to the dye resist effect toward anionic dyes. Resist effectiveness improves sig nificantly with increasing molecular weight (diffusion hindrance of the dye) for low auxiliary concentrations on the fiber. Further, increasing acidity of the auxiliary gives a better resist effect. In addition to the number of ionic charges, their distribution in the auxiliary molecule proves to be important to the resist effect.

Changes in the appearance of carpet pile due to mechanical wear are usually ac companied by changes in apparent color. This paper describes the application of color image analysis to measurements of color variations. We characterize color by converting digitized RGB into HSV, XYZ, and L*a*b* systems. While color appears to change in some of the carpets we evaluated, color change is always accompanied by a cor responding change in brightness or gray level.