Textile Research Journal

Extracting flax fibers from the stems of Linum usitatissimum plants has traditionally been a costly, labor-intensive process, largely restricted to Europe and Asia. The naturally long, strong fibers are typically processed on wet spinning machines that are not available in the United States. However, the resurgent popularity of flax has promoted an interest in devising more economical methods of producing and processing the fibers domestically. This preliminary study investigates the use of flax fibers extracted by mechanical, chemical, and enzymatic retting as well as traditional (dew) retting methods. The experimental fibers show promise for spinning on common cotton machinery in blends with cotton. The research has produced a series of medium-count, experimental apparel-grade yarns with an attractive appearance and acceptable hand. With refinement, chemical or enzyme retting can perhaps become an ecologically sound and cost effective method of producing flax fibers.

Elastic fabrics used to make pressure garments are normally cut in various sizes and different aspect ratios (i.e., width of fabric divided by gauge length). Because the aspect ratio may vary the load-strain relationships measured from the elastic fabric, the resultant pressure of a tubular elastic fabric exerted on the cylindrical surface may vary. This study investigates the effect of aspect ratio of a tubular elastic fabric on pressure changes in making up pressure garments. Both the theoretical analysis and experimental study are presented, and results from both are in close agreement.

The influence of knitting machine characteristics and yarn properties on tensions occurring in yarn during knitting is investigated. The process is dynamically analyzed by means of frequency analysis for three grades of cotton yarn fineness and two of wool yarn. Signal analysis done numerically using discrete Fourier transform (DFT) results in force signals with one-sided and double-sided spectra. Some characteristic signals are presented with appropriate DFT to help determine the influence of yarn, package quality, and yarn feeding on signal spectra.

Cotton fabric is desized with amyloglucosidase and combined with bioscouring with two different kinds of pectinase in the presence and absence of cellulase. The treatment bath, rich in glucose, is initially reused for biobleaching with glucose oxidase under neutral conditions. Finally, all three preparatory processes are combined. The whiteness, water absorbency, tensile strength, and degree of polymerization of the treated cotton goods are evaluated. The process yields products with acceptable whiteness very close to the whiteness of commercially bleached goods and excellent mechanical properties. The amount of rinse water can be drastically reduced.

The potential of ultrasound as a means of enhancing dyeing efficiency is evaluated. Changes in the particle sizes of a disperse dye dispersion with ultrasound irradiation are studied using the turbidity concept, and the effect of particle size on the exhaustion rate is also investigated. Ultrasound irradiation of a dye dispersion reduces the particle sizes of disperse dyes, and the exhaustion rate of the dyes on fibers is enhanced by this reduced particle size by the ultrasound pretreatment before dyeing experiments.

Three fluoropolymer latices, two of them commercially available and the third synthesized as a reference material, are applied by padding to wool, cotton, and polyester fabrics, and their performance is evaluated by means of technological standard test methods for water repellency, oil repellency, fabric hand, and mechanical properties. Surface modifications are further characterized by electron microscopy and less conventional techniques such as static and dynamic contact angle measurements, in order to assess the relevance of the surface composition and structure, at the microscopic level, for the observed properties of the fabric at the macroscopic level. The fluorinated coating does not significantly alter textile hand. Improved water and oil repellency, assessed by technological tests, generally correlate well to observed static and dynamic contact angle variations, although the latter are the result of a combination of contributions, including those deriving from composition and morphological heterogeneity of the surface exposed to wetting.

The pore volume and surface area of cotton fabric are dominant parameters in determining the accessibility of dyes and finishes during wet processing. Cellulase enzyme hydrolysis of cellulose may result in changes in pore volume and surface area of the fabric. This work characterizes these changes using size exclusion liquid chromatography with cotton in the form of rolled stationary phases, which are prepared by rolling and inserting a whole woven fabric into a chromatography column, and pore volume and surface area of the enzyme treated cotton are then determined. The volume and surface area of pores smaller than 60 Å in cotton fabric decreases after cellulase enzyme treatment, and does not change for pores larger than 60 Å. This method shows that enzyme hydrolysis significantly decreases small pores in cotton fabric. Direct dyed samples show no observable color difference between untreated and enzyme treated cotton.

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.

We have investigated the potential of fungal laccases from Polyporus sp. and Sclerotium rolfsii to degrade insoluble indigo. Evidence shows that both laccases are able to oxidize insoluble indigo to give isatin (indole-2,3-dione), which further degrades to anthranilic acid (2-aminobenzoic acid). Adsorption studies show that the laccase from Polyporus sp. has a higher affinity for indigo than the laccase of Sclerotium rolfsii. The particle size of indigo agglomerates is influenced by the origin of the laccase preparation and the incubation time. The potential of laccases to modify indigo stained fabrics is assessed. Treatment of indigo dyed fabrics with laccase prevents indigo backstaining, and Polyporus sp. appears to be more effective for reducing backstaining.

Our previous work demonstrated that proteases are effective scouring agents for boiling-water pretreated cotton fabrics. In this study, we investigate whether proteases are effective scouring agents when directly applied on raw greige cotton fabrics without the boiling water pretreatment. Direct reactions with three proteases, i.e., trypsin, chymotrypsin, and subtilisin, on greige cotton fabrics show that all three improve fabric wettability to a level similar to alkaline scouring under mild conditions (45-55°C, pH 7). The reaction conditions required to achieve optimal fabric wettability (cosθ > 0.6) are 5 g/L and 45°C for trypsin and 5 ml/L at 55°C for subtilisin. Chymotrypsin is effective under several reaction conditions, i.e., 1 g/L at 55°C, 2 g/L at 45°C, and 5 g/L at 35°C. Most reactions take 30 minutes, and room-temperature water rinses replace the post-reaction buffer rinses. Compared to protease scouring of boiling-water pretreated cotton, direct protease scouring of greige cotton fabrics requires increased concentration (subtilisin), higher temperature (subtilisin and chymotrypsin), or longer time (trypsin and chymotrypsin) to achieve similar water wettability and absorption properties. The most distinct outcome of direct protease scouring of greige cotton fabrics, in comparison to boiling-water pretreated and protease scoured and alkaline scoured cotton, are the resulting fabric characteristics, i.e., less lateral shrinkage, no change in surface friction, easier to shear, and more resilient to compression and bending.

The knot performance of four different nonabsorbable sutures—silk, polyester, polyamide, and polypropylene—is investigated by using square knots with two and three throws. All sutures are USP 2/0 in size. An instrument that can be mounted on the Instron tensile tester measures the knot performance of the sutures. The results are given as stress-elongation graphic, knot slippage, and knot break values. The effects of the number of throws and the structure of the sutures on knot performance are studied. For the knot performance tests, the effect of the physical structure (braided or monofilament) is clearly seen. For monofilament polyamide and polypropylene sutures, the knot with two throws unties before it breaks. For silk and polyester braided sutures, which have reasonably good two-throw square knot strength, the added throw does not remarkably increase strength and at the same time places more suture material in the tissue, which increases the risk of infection. Three-throw knot results reveal that the suture material plays an important role in knot strength.

We treat naturally pigmented karakul wool with a surface modification system of chlorination and catalytic bleaching, then examine its structure and properties. SEM photos reveal the surface morphology of karakul wool, and the Allwörden reaction shows the extent of damage to the epicuticle. The results show that the surface modification removes the bulk of the fiber scales and bleaching increases fiber whiteness. After bleaching, the felting propensity of karakul wool improves slightly and its dye uptake decreases. For modified and bleached karakul wool, the felting propensity decreases, the dyeing rate increases, and equilibrium exhaustion decreases compared with untreated karakul wool.

A new evaluation system is presented for measuring the smoothness appearance of fabric surfaces objectively and quantitatively. In this system, the contour of the fabric surface is measured with the stereo vision algorithm, and the data are then used to evaluate fabric smoothness by fractal geometry, which explicitly explains the degree of ruggedness of the fabric surface as a decimal fraction with precise grading. This study illustrates the stereo vision technique and its image processing for 3D measurements of surface contours using AATCC Test Method 124. The fractal dimensions of replicas are obtained by a fractal geometry algorithm such as reticular cell counting or cube counting. A new equation is established from a linear regression between the fractal dimensions of replicas and their grades. The experimental results show that the new grading based on 3D vision and the fractal dimension corresponds to a visual assessment of fabric smoothness with more accuracy and reliability. The new equation based on the fractal dimension should determine an objective rating of fabric smoothness that can substitute for the conventional subjective AATCC rating method for fabric smoothness and provide a quantitative reliable value to assess fabric smoothness with more accuracy and reproducibility.

In Part I of this study, we explained the method of producing a hollow yarn on a friction spinning machine and then considered its tensile properties. In this part of our study, we consider the structural properties of that yarn and the effect of axial and lateral forces on its structure, such as diameter changes, ellipticity, compressibility, and volume. We compare the properties of hollow yarns with those of equivalent 100% cotton yarns. The results indicate that stretching tension may affect the yarn diameter variation but not its linear density. The yarn diameter is bigger than that of conventional cotton yarn, and it decreases with increasing axial tension, which also happens to a conventional cotton yarn. Other results show that the yarn ellipticity ratio is greater than that of the cotton yarn and that it increases with increasing PVA percentage in the hollow yarn. In addition to higher compressibility, the hollow yarn shows better recovery. The volume of hollow yarn after compression is also greater than that of conventional cotton yarn.

The fatigue behavior of technical polyamide 66 fibers is studied using two samples with different diameters. First, the structural and viscoelastic properties are characterized, and then loading criteria for fatigue failure are identified. The fatigue fracture morphology revealed by scanning electron microscopy is quite different from simple tensile fracture morphology. Many theories have been advanced to explain the fatigue failure phenomenon. This work shows that fatigue failure is initiated at the surface of the fiber and not in the interior, as some using the Prevorsek model have suggested. On the other hand, fatigue failure is independent of fiber geometry, and a relaxation thermal treatment considerably reduces fatigue.