Textile Research Journal

Past research has demonstrated that the fundamental properties of wall thickness and perimeter, computed from the fmt (Micromat model) readings, produce better correlations with the Southern Regional Research Center (SRRC) near-infrared high volume instrumentation (nir hvi) than similar property data from the afis fineness and maturity module. (The nir hvi analyzes about 3,000,000 fibers or 30 g, the Micromat 400,000 fibers or 4 g, and the afis 5000 fibers or 0.05 g, a single fiber at a time.) To help understand these differences in correlation, we probe the random and systematic variations in the Micromat and afis data using appropriate data analysis techniques. We present descriptive statistics and an internal correlation of paired means from replicate measurements, and we compare the fit of wall thickness versus perimeter with the expected theoretical fit. Preliminary results suggest that the Micromat is more robust in representing changes in mean wall thickness and perimeter values. Direct comparison of wall thickness and perimeter from each method shows that although the relationships are highly significant, the values are different.

The dyeing behavior of 1,4-diaminoanthraquinone (1,4-daa), CI Disperse Violet 1 on polyester fibers is investigated in the presence of a double tailed surfactant, dialkyldimethylammonium bromide (dadmab), which is known to form a bilayer. Both dyeing rate and saturation values of 1,4-daa are considerably improved at 110°C in the presence of dadmab compared with those of a dyehouse grade, Miketon Fast Red Violet R. It is likely that the enhanced dyeing properties with dadmab are due to interactions between it and the polyester fibers or between it and the dye.

This research explores the application of an image transform technique, the Hough transform (ht), to measuring fiber orientation distribution in nonwoven fabrics. In this paper, various forms of the ht for straight lines and the implementing algorithms are presented, the factors that may influence the accuracy of ht results are discussed, and the way to determine fiber orientation distribution from ht data for a nonwoven is explained. The usefulness of the ht method is tested using simulated nonwoven images with known dominant fiber orientations, and nonwoven fabrics differing in fiber content, weight, and other characteristics. Fiber orientation distributions generated by the ht method are also compared with those obtained from the zero-span tensile testing method. The principal advantages of using the ht are that it is robust in suppressing image noise and is able to deal with fibers containing gaps and breaks. Measurements with the ht method show good correlation with those obtained from other methods. The ht appears to be an effective and efficient image analysis technique for extracting information about fiber orientation from images of nonwoven fabrics.

Kinetic and optical behaviors of Cibacron™ Yellow R, Scarlet 2GE, and Blue TRE are studied individually and in mixtures. In mixtures, these dyes deviate from their individual behaviors. A method for determining these deviations and for correlating the optical and kinetic deviations is demonstrated. This method is valuable because it allows the kinetic behavior of dyes in mixtures to be characterized from simple optical measurements.

Wool fibers are “impact cut” with a rotating blade made from piano wire at various positions along the fibers. The force transmitted to the base of the fibers decreases markedly when a critical velocity (from 140 to 270 m/s) is exceeded, with corresponding improvement in the cut surface. The velocity of the wire required for impact cutting varys according to the length of the fiber above and below the impact position; fibers with long lengths above the wire impact position are impact cut at lower wire velocities than shorter fibers. Fibers impact cut above the critical wire velocity are cut by tensile failure of the fiber, produced by the inertia of the fiber being accelerated by the impacting wire. To prevent damage to the fiber tip, the feed rate of the cutter into the wool should be high. Impact cutting may be a viable means of harvesting wool from skins or even live sheep.

The effects of fabric made from natural and synthetic fibers and film on transepidermal water loss (tewl) from the stratum corneum (sc) were investigated using an occluded system. Sixteen fabrics differing in fiber type and construction were placed on the volar forearm of 35 female subjects in a dry state (standard moisture regain) and a wetted state. Each fabric was in place for 40 minutes before tewl was measured. There was no statistically significant difference in tewl measurements on a control skin site from the beginning to the end of the 75-minute test session in a controlled conditioned environment. Placement of dry fabrics on the skin did not significantly affect the hydration level of the sc, though all dry fabrics did increase the hydration level slightly. Wetted wool and cotton fabrics significantly hydrated the sc when levels were compared to either normal skin or skin covered by dry fabrics. Of the seven synthetic fiber fabrics tested in a wetted state, three (acrylic, ptfe, and spun nylon) significantly increased the sc hydration level. These three fabrics and the natural fiber fabrics had comparable wetted moisture content.

This study of the shear strength of fibrous sheets first measures the in-plane shear strengths of various samples, including woven and nonwoven fabrics and paper, using a custom-made apparatus attached to an Instron tester. The structure of the apparatus and the measurement procedures are introduced in this article. The tested shear strength values are then compared with theoretical predictions from an earlier work. Discrepancies and possible causes are analyzed. Load-elongation curves for both tensile and shear are compared for individual fabrics and between fabrics. The relationship between the anisotropy of fabric tensile strength and the ratio of tested and predicted shear strength is explored. Also, the effect of fiber movement during textile deformation is examined. Finally, the original Tsai-Wu theory used for shear strength prediction of anisotropic materials is modified for application to the fibrous sheets, and the new predictions are provided for comparison.

We investigate the effects of the cross-sectional structure of a polyester-type polyurethane (pu)/polyvinylchloride (pvc) blend dope-coated nylon fabric on moisture permeability. The waterproof coating is applied by a one-sided wet-coagulation process. The blending of hydrophobic pvc to hydrophilic pu forms a three-layered cross-sectional structure—a pvc-rich micronetwork, a porous pu-rich layer, and the nylon fabric. As the blend ratio of pvc to pu increases, the moisture permeability (mp) and dew condensation (dc) of the coated fabrics improve. Compared to the pu homopolymer, the mp value of a pu/pvc blend in a weight ratio of 4:1 increases 1.18 times to 492 g/m²·h (JIS A-1 method) and 1.16 times to 815 g/m²·h (JIS B-1 method), but the dc value decreases one-fourth to 4.60 g/m² · h. This gradient three-layered cross-sectional structure contributes to vapor transport properties.

Closed-loop control of the dosing of dyes and chemicals is used to obtain an on-tone build-up of shade in dyeing polyamide fibers with a binary mixture of monosulfonated acid dyes. Computerized dosing pumps control the pH, the dyebath concentrations of the individual dyes, and the total sorption of each dye during the process. This real-time, closed-loop adaptive control yields good reproducibility and uniform shade build-up in a laboratory dyeing machine. It is possible to reuse a dyebath containing residual dyes and chemicals from a previous dyeing.