Textile Research Journal recent issues

Covalent Modification of the Wool Fiber Surface: Removal of the Outer Lipid Layer

Meade, S. J., Dyer, J. M., Caldwell, J. P., Bryson, W. G. — 2008-10-30

This investigation provided a comparative assessment of strategies for the removal of 18-methyleicosanoic acid (18-MEA), and other surface bound lipids enveloping the wool fiber surface, by chemical and physical cleavage of the thioester bond. The removal of this lipid layer reveals an underlying proteinaceous layer, exposing functional chemical groups available for covalent attachment of new molecular or nanoparticulate entities by chosen treatments. Lipid removal treatments employing methanolic potassium hydroxide, t -butoxide in t-butanol, and aqueous hydroxylamine and a physical atmospheric pressure glow discharge (APGD) plasma treatment were compared. Treated wool fabrics were subsequently characterized by analysis of the exposed groups on the fiber surface by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), with the bulk surface properties of the fabrics assessed employing wettability testing techniques. An evaluation of chemical and plasma methods for removal of the surface bound lipid layer resulted in the selection of aqueous hydroxylamine/ non-ionic surfactant as the optimal treatment method for subsequent covalent attachment of novel entities by surface treatments. Optimized aqueous hydroxylamine treatment was found to remove up to 77% of the surface bound 18-MEA, providing a marked increase in surface wettability, without significantly affecting the handle of the treated fabric. Surface characterization demonstrated that the hydroxylamine treatment produces an increase in surface friction, with uniform and controlled removal of the surface lipid layer, and minimal surface oxidation of the surface thiols. Minimizing surface oxidation of thiols was a critical target of surface lipid removal in this study, as it maximizes the potential for subsequent surface modification via covalent attachment. The use of aqueous conditions, short reaction times, and moderate temperatures with hydroxylamine treatment are advantageous in comparison with treatments employing non-aqueous solvents such as methanol and anhydrous t-butanol. The economic and environmental advantages of an aqueous, effective, and non-damaging approach to surface lipid removal highlight this approach as a potential avenue for future textile application of novel wool surface chemistries.

Manufacturing and Properties of PLA Absorbable Surgical Suture

Lou, C.-W., Yao, C.-H., Chen, Y.-S., Hsieh, T.-C., Lin, J.-H., Hsing, W.-H. — 2008-10-30

Polylactic acid (PLA) is a polymer that has good biocompatibility, good biodegradability and excellent mechanical properties. The modulus of elasticity and the thermoplastic ability of PLA can satisfy the need for the carrier material of the cell to grow in bone tissue engineering, such as in regeneration and repair of bone and cartilage tissue. The PLA multifilament was twisted using different twisting parameters and a rotor-twister to fabricate United States Pharmacopoeia (U.S.P.) size 5-0 and 7-0 surgical sutures. The best tensile strengths were 3.1 and 12.3 N, and the coefficients of variation were 3.70% and 1.75%. The PLA suture was then scoured with 1 wt% sodium hydroxide to eliminate impurities, and the knot-pull strengths decreased to 1.66 and 6.84 N for 7-0 and 5-0 PLA sutures, respectively, but still conforming to the U.S.P. knot-pull strength standard. An in vitro hydrolysis test was performed at 37°C by immersing 5-0 PLA suture in physiological saline (0.9 wt% NaCl aqueous solution); the knot-pull strength decreased by 12% after 28 days.

Experimental Investigation of Effects of Spandex Brand and Tightness Factor on Dimensional and Physical Properties of Cotton/Spandex Single Jersey Fabrics

Tezel, S., Kavusturan, Y. — 2008-10-30

In this study, the effects of spandex brand, the tightness factor of the base, and spandex yarn on the dimensional and physical properties of cotton/spandex single jersey fabrics are investigated. In order to examine the effects of the tightness factor of cotton and spandex yarn, fabric samples were knitted by feeding both cotton and spandex yarns with three different adjustments of positive yarn feeding mechanisms so as to produce tight, medium, and loose cotton/spandex single jersey fabrics. Four different spandex yarns were used. The fabrics knitted with spandex yarns that have the largest tension values under a constant draw ratio give the highest weight, courses/cm, stitches/cm, thickness, and lowest air permeability values. Spandex yarns that have similar elongation % values affect the wale per cm values in a similar way. Because of the greater stretched structure of the spandex yarns that have shorter loop length values, the width of the fabric decreases and then the thickness of the fabric increases.

Static Tearing, Part II: Analysis of Stages of Static Tearing in Cotton Fabrics for Wing-shaped Test Specimens

Witkowska, B., Frydrych, I. — 2008-10-30

We present here an analysis of the stages of static tearing in cotton fabrics for wing-shaped test specimens. For the analysis and measurements of geometry of the tearing zone, a program for image analysis was realized and video film elaborated. Moreover, the influence of the constructional features of woven fabrics and fabric structure, and also the testing conditions on the tear force and tearing zone parameters were examined.

Measurements of Moisture Transport within Multi-layer Clothing Assemblies Consisting of Different Types of Batting: A Factorial Design Analysis

Huijun Wu, , Jintu Fan, — 2008-10-30

A three-level two-factor (3²) full factorial design was conducted to examine the effects of the batting constructions (e.g. batting types and positions) on moisture transport through multi-layer clothing assemblies consisting of different types of batting under subzero environmental conditions. The amounts of moisture accumulated within and transmitted through the different batting constructions during a 24 h period at —20^oC were measured on a developed sweating guarded hot plate. The factorial analysis on the experimental results showed that the inner batting type had the most significant influence on moisture accumulation and transmission within the clothing assemblies, although the effects of the outer batting type and the interaction between the inner and outer batting types were also significant. The analysis showed that placing wool batting instead of down batting in the inner region could efficiently minimize the moisture accumulation within the batting constructions and consequently upgrade the thermal comfort of the cold protective clothing systems.

Effects of Topographic Structure on Wettability of Differently Woven Fabrics

Hasan, M.M.B., Calvimontes, A., Synytska, A., Dutschk, V. — 2008-10-30

Optical analysis of roughness operating on the principle of chromatic aberration and dynamic wetting measurements have been used to investigate the surface properties of polyester fabrics with different woven structures. The results revealed differences in the two basic types of weave — plain and twill — with respect to the penetration behavior of water. Additionally, plain weave fabrics were manufactured using differently profiled fibers — round and cruciform. It was established that fabrics composed of fibers having a cruciform cross section are more hydrophobic than those that are round.

It was shown that topographical characteristics of the fabrics strongly depend on their construction parameters such as the type and fineness of filaments, yarn fineness, yarn density, and, consequently, the type of weave. The results provide further insight into the relationship between construction parameters of fabrics of the same chemical nature and their topographic and wetting properties.

A Comparative Study on Accelerated Weathering Tests of Wool Fabrics

Hu Zhang, , Cookson, P., Xungai Wang, — 2008-10-30

This work has used two lightboxes with Philips 500 W MBTF lamps for a comparative trial on the photoyellowing evaluation of untreated wool fabrics under dry and wet conditions. An investigation was made to account for different trends of photoyellowing of the same wool fabric when irradiated by the two lightboxes. The fabric specimens irradiated in one lamp experienced increasing yellowing with irradiation time while specimens from the same wool fabric but irradiated under the other lamp manifested no noticeable color change. These differences are attributed to the susceptibility of wool to small spectral differences between the two MBTF lamps. Furthermore, the color fading results obtained from the commonly used blue wool standard (BWS) references from L1 to L3 show that these reference materials could not effectively reveal changes caused by the spectral differences in two MBTF lamps. These results have important implications for conducting accelerated weathering tests on spectrum-sensitive textile materials, and considerable care should be taken when using BWSs to ensure reliable and consistent irradiation results.

Design, Manufacture, and Experimental Analysis of 3D Honeycomb Textile Composites, Part II: Experimental Analysis

Xiaogang Chen, , Ying Sun, , Xiaozhou Gong, — 2008-10-30

In the second part of this two-part paper, the experimental analysis of 14 systematically designed 3D honeycomb textile composites, using drop-weight impact tests, is described. Energy absorption and transmitted force were measured to determine the impact performance of the honeycomb composites. The influence of structural parameters, including cell opening angle, cell size, cell wall ratio, and the cell density for the same cross-sectional area, were studied to characterize the 3D honeycomb composites systematically. It was found that changes in structural parameters affect impact energy absorption and impact force attenuation. The effect of volume density of the honeycomb composites on impact characteristics was also investigated. The results indicate that while the volume density has little effect on the energy absorption, it has significant influence on the transmitted force. The analytical results provide useful data for the engineering and application of 3D honeycomb composites.

On Convergence Point of the Two-strand Yarn Spinning

He, J.-H., Zhang, L.-N. — 2008-10-30

The convergence point of two-strand yarn spinning was determined by the densities and velocities of two strands and the spun yarn, independent of their mechanical properties.

Temperature Analysis for the Prediction of Steam Formation and Transfer in Multilayer Thermal Protective Clothing at Low Level Thermal Radiation

Keiser, C., Rossi, R. M. — 2008-10-30

It is important to understand the process of evaporation and steam transfer through firefighter protective clothing in order to be able to prevent steam burns. As humidity sensors are too slow to measure fast changes of humidity inside the clothing layers, temperature changes were used to analyze the evaporation of moisture. Temperature measurements turned out to be useful to predict the evaporation speed within the clothing layers, as temperatures remain constant during the evaporation. The measurements showed that the temperatures within the clothing layers containing a wet layer never rose higher than the temperatures within dry clothing. As soon as all moisture had evaporated, temperature increase followed exactly the curves of the measurements of dry samples.

Abstracts: Sen'i Gakkaishi, Vol. 64, No.11

2008-10-30

Future Events

2008-10-30

Occurrence of a Singular Point in a Bundle Flow System and the Sensitivity of the Bundle Thickness to Perturbations in a Steady State Draft Process

Huh, Y., Kim, J. S. — 2008-09-23

Roll drafting is an important unit operation that transforms fiber bundles into attenuated ones, improving their properties with more efficient material usage. Fibers are thus thrown into a flow field having constraints at both ends incurring layer-to-layer flow shearing, which governs the individual fiber movement. The parameters of the flow characteristics are disturbed or changed during processing and the output of the roll drafting operation can have either more or less fluctuating properties. In this research, we perturbed the model parameters related to the roll drafting process to identify their effects on the process dynamics and consequently the quality of the processed product. Based on the random phase spectral method, stochastic signals having an exponentially decaying auto-correlation function were generated and applied to the mathematical model that described the dynamic behavior of the flowing bundle. Thus, the profiles of the linear density and velocity of the bundle flow field in steady state were simulated. In extreme perturbations the bundle can break, which was simulated and confirmed by experiments. This research showed that a singular point in the draft zone existed which implied a bundle breakage. The singular point in the draft zone could be attributed to the inadequate set-up of the process conditions, specifically, to two parameters in the model: one was related to the bundle properties and the other to the process conditions. Considering the bundle property related parameter as a stochastic process, the range of the parameter variation to ensure a continuous drafting operation was limited. The influence of the perturbations on the draft process also became more sensitive as the process speed and the draft ratio increased.

Objective Evaluation of Fabric Handle by Simple Measurement Methods

Sular, V., Okur, A. — 2008-09-23

In this study, objective and subjective evaluations of fabrics were made to predict fabric handle in a simple way. The aim of this research was to select a suitable form of regression model and predict total handle value with a minimum number of parameters to make a practical approach by using simple laboratory measurements. For this purpose, a wide database of 71 worsted men's suitings was prepared by making subjective and objective evaluations. Subjective tests of primary handle attributes (softness-stiffness, thickness-thinness, and roughness-smoothness) and total handle were evaluated by an expert jury consisting of 18 members, and a subjective total handle value was also calculated using these data. Objective measurements consisted of fabric tensile, bending, shear, compression and surface properties, and pulling through a nozzle tests. A new surface roughness tester was used for measuring surface properties, and it was found that these roughness results might be useful for fabric handle prediction. Linear and log linear regression equations were tested by using 43 parameters. Consequently, some simple regression equations that were practical solutions were obtained to predict fabric handle. A very good result was obtained with a value of the adjusted R² = 0.88 with eight parameters (LOGP1, LOGB, T42, Rq1, Rp2, Rq1, Rp_mean, P1) from four different property blocks (pulling through a nozzle, bending, tensile, and surface), and in particular, the regression equations reaching an adjusted R² value over 0.80 are recommended.

Techniques for Torque Modification of Singles Ring Spun Yarns

Bin Gang Xu, , Xiao Ming Tao, — 2008-09-23

This article reports on a systematic study of various spinning techniques to produce torque-free singles ring spun yarns on a modified ring frame. The modification units, including optional fiber separation devices and a false twist device, were incorporated into the conventional ring spinning frame so that the balanced or reduced yarn residual torque could be achieved in one step. Three modification systems were proposed and two of them were investigated on a ring frame to produce pure cotton singles yarns. The spirality of the resultant single jersey knit fabrics was greatly reduced. Properties and performance characteristics of control and modified yarns, as well as their resultant fabrics, were evaluated, including yarn tensile properties, hairiness, evenness, snarling, burst strength, air permeability, handle, and pill resistances.

Revision on the Titration Method for Accurately Measuring the Amounts of Residual Monomers in Polyacrylic Sizes

Zhifeng Zhu, , Jie Yu, , Kun Qian, , Cuiyun Yu, — 2008-09-23

An attempt has been made to develop a revised titration method for accurately measuring the content of residual monomers in polyacrylic sizes. It was found that the conventional titration method widely used nowadays for the content measurement cannot determine the content accurately if a certain number of hydrophobic structural units are contained in the size macromolecules. Since most mills and size companies do not possess a chromatograph, a revised titration method is studied and proposed. By choosing three to four sample weights in the range of 0.1— 0.6 g to achieve three to four corresponding values of the monomer content, a straight regression line can be easily obtained in a coordinate. The ordinate value of intersection of the line with ordinate is just the measured value. A gas chromatograph demonstrates that the revised method is suitable for the determination of the content when the polymeric molecules of the sizing agents incorporate hydrophobic constitutional units. The effectiveness and accuracy of the revised method are examined by mixing a known amount of monomer into the sizes. The results demonstrate that the regression and chromatograph values are correlated well and the differences are relatively small. The accuracy of the revised method is much higher than that of the original one.

Investigation of the Water Repellence of Different Experimental and Commercial Coatings for Synthetic Mountaineering Ropes

Spierings, A.B., Ritter, A., Henkel, O., Holzdoerfer, U. — 2008-09-23

All manufacturers of synthetic mountaineering ropes provide chemically coated ropes in order to reduce their water uptake in a wet environment. As common static test methods for the investigation of the water repellent behavior of ropes do not move or bend the ropes, the measured water uptakes are usually below about 10%. In this study we have investigated the water uptake of coated ropes under conditions that are closer to practice conditions than all other methods. Our results show that commercially coated ropes provide a sufficient water repellent behavior as long as the ropes are not in practical use with, for example, carabiners. As soon as the ropes sustain a practical use, the water is worked through the sheath into the core of the ropes so that the water uptake is comparable to the values of uncoated ropes. As a result, the safety performance is decreased both in terms of the number of drops sustained and the impact load. Furthermore, we have investigated experimental coatings and found one chemical (a wax-based coating) and one physical (plastic tape between the sheath and the core of the rope) coating, which were both able to reduce the water uptake even in dynamic conditions.

Application of Stretch-breaking Force Analysis on Optimum Drafting Conditions in Tow-to-yarn Direct Spinning

Su, C.-I., Huang, L.-Y., Cheng, S.-P. — 2008-09-23

This study discusses the evaluation of stretch-breaking force and its CV% in the tow-to-yarn direct spinning with 12k oxidized filament tow. We aimed to describe a new method for determining suitable draft conditions in the direct spinning to obtain the best oxidized yarn quality. To correlate the stretch-breaking force and the yarn quality, oxidized direct spun yarns were spun on a modified laboratory spinning frame for one-step conversion of a tow-to-yarn system. Base on the correlation of stretch-breaking force CV and direct oxidized yarn quality, the drafting ratio and roller gauge corresponding to the lower unevenness (CV%) of the direct oxidized yarn could be chosen as the suitable draft condition in direct yarn spinning to obtain the best oxidized yarn quality. Obviously, the results revealed that the technique of stretch-breaking force could be applied on the optimum draft condition of tow-to-yarn direct spinning.

Simulating Liquid Flow through Virtual Glass Fiber Mats

Jaganathan, S., Maze, B., Vahedi Tafreshi, H., Pourdeyhimi, B. — 2008-09-23

The focus of this paper is on simulating the in-plane and through-plane penetration of liquid water in virtual non-wovens. We consider a series of unsteady state two-phase (air—water) simulations performed in two-dimensional geometries obtained from a simulated three-dimensional glass fiber mat. The simulation planes are the cross-sectional planes in the horizontal and vertical directions. Simulations revealed that liquid penetration and spread depend strongly on the fiber orientation distribution as well as on the hydrophilic properties of the fibers. Our results are in good qualitative agreement with the available experimental data.

Comparing and Modeling the Dynamic Drape of Four Natural-fiber Fabrics

Lin, J.-Y., Wang, P.-N., Shyr, T.-W. — 2008-09-23

This study primarily analyzed the dynamic drape coefficient of four natural-fiber fabrics at speeds of 0—450 rpm. A tangent partition method was used to divide the drape coefficient curve into four regions, characterized as drape coefficient increment initial growth, fast growth, slow growth and dynamic stable regions. The ANOVA test was used for validation. The dynamic drape coefficients of these four natural-fiber fabrics were then compared. The order of the drape coefficient of these fabrics changed three times in the fast growth region and then remained unchanged throughout the slow growth and dynamic stable regions. The order of the static drape coefficient of fabrics could not represent the drape coefficient of fabrics in dynamic performance. Therefore, a linear model, a growth model and a nonlinear logistic model were used to analyze the dynamic drape coefficient curve fit, and the F-test was used for validation. The results showed that the nonlinear logistic function could be used to fit the drape coefficient curves throughout the static state and the dynamic stable region.

Analysis of Geometrical Parameters using a CAD System for a 3-D Braided Preform

Tea Jin Kang, , Kim, S., Jung, K. — 2008-09-23

To estimate the precise mechanical properties of the three-dimensional (3-D) braided composite, a geometric study of a 3-D braided preform was performed. Describing yarn paths using third-order spline curves, which are close to the real pathway of the 3-D braided structure, the unit cells and the representative volume elements were determined. Finally, the CAD system for the 3-D circular braided preform was developed following these modeling sequences and applied to the parametric study of the preforms. A parametric study was conducted on the important geometric factors such as yarn retraction factor, yarn orientation angle, and yarn volume fraction and the theoretical maximum yarn volume fraction was determined. Using the developed CAD system, the relationships between processing variables and geometric parameters have been established.

Sen'i Gakkaishi, Vol. 64, No.10

2008-09-23

Future Events

2008-09-23

Automatic Weave Diagram Construction from Yarn Positional Data of Woven Fabric

Shinohara, T., Takayama, J.-Y., Ohyama, S., Kobayashi, A. — 2008-08-21

We propose a novel automatic weave diagram construction method from yarn positional data of woven fabric. In this work, a set of yarn positional data implies a sequence of center points of a yarn obtained using the yarn tracing method proposed in our previous study. For constructing the weave diagram, the sets of yarn positional data are first divided into warp and weft based on the gradient of a line, which approximates the yarn positional data. The intersections between warp and weft are then calculated using the approximated lines. Then the weave diagram is constructed by comparing the warp positions with the weft positions at all the intersections. The effectiveness of the automatic weave diagram construction method is confirmed by experimentally applying this method to the yarn positional data of a double-layered woven fabric.

Assessing the Wear of the Oxide Layer of a Spindle-neck Coating with a Collapsed Balloon Crown

Plonka, S. — 2008-08-21

The results of an investigation into the wear of the spindle-neck coating with a collapsed balloon crown of a ring-spinning frame during mating with the yarn under industrial conditions is presented. The investigation included examining the wear of the spindle-neck coating made of aluminum alloy 2024, which was subjected to the following different methods of finishing: grinding with abrasive cloth, burnishing only, and burnishing followed by hard anodic oxidation. The analysis of the process of wear and the thickness of the oxide layer before and after the operation has confirmed that the oxide layer increases the wear resistance by several orders of magnitude. It was also concluded that hard anodic oxidation gives the spindle-neck coating a durability equal to the lifetime of the bearing inserts. We assessed the surface topography by means of microphotography, the yarn kinetic friction coefficient µ _k , and the microstructure of the oxide layer before and after the period of operation. This allowed us to find out that the wear of the spindle-neck coating caused by the friction of yarn on the surfaces is determined by the abrasive wear.

A New Tester and Method for Measuring Fabric Stiffness and Drape

Sun, M.N. — 2008-08-21

A new tester which uses a cross-shaped specimen to measure fabric drape and stiffness is proposed. The warp and the weft strips of the specimen are supported at the central part and bend under its own weight. The x and y coordinates of the hanging strips are measured so that the drape angles can be calculated. The way that the warp and the weft strips drape can be determined from one measurement. Using Peirce's formula, the conventional bending length and flexural rigidity can also be found. There is a strong correlation with measurements made using the Shirley stiffness tester and the Fabric Assurance by Simple Testing (FAST)-2 bending meter of FAST system.

Design, Manufacture, and Experimental Analysis of 3D Honeycomb Textile Composites Part I: Design and Manufacture

Xiaogang Chen, , Ying Sun, , Xiaozhou Gong, — 2008-08-21

Textile composites have the advantage of being strong and lightweight over the conventional materials, and thus have found applications in many areas, most notably for materials used in aircraft. In this two-part paper, the engineering design and characterization of 3D honeycomb composites are described on the basis of an attempt to create a novel type of composite material which is extra lightweight and voluminous. The first part of the paper explains the basic concept of 3D honeycomb composites, and the procedure of design and manufacture of 3D honeycomb fabrics and composites. An algorithm has been established to create weaves based on the specification of the 3D honeycomb composite parameters, and this algorithm has been implemented into a computerized procedure which gives accurate solutions for making reinforcing fabrics of this type. It has been demonstrated that 3D honeycomb textile composites with various structural parameters can be engineered. Four groups of honeycomb composites, involving 14 varieties, have been systematically created for the first time in order for the experimental analysis of the honeycomb composites to be carried out. A simple yet effective method for making honeycomb textile composite is described in Part I. The experimental analysis and the results will be described in Part II of this paper.

Objective Evaluation of Soil Release in Fabrics

Gururajan, A., Hequet, E. F., Sari-Sarraf, H. — 2008-08-21

Soil release is an important attribute of fabrics that impacts their pricing on the marketplace. Currently, stain release is evaluated manually and hence its assessment tends to be subjective. This paper introduces a novel approach based on image analysis for objective evaluation of stain release in fabrics. This system has the capability to accurately detect, localize and grade stains with minimal human intervention. The grades assigned by the system are based on a digitized version of the AATCC soil release replica. The stain detection performance of the system was validated on a large dataset of 360 stain images. The system produced excellent results with a sensitivity (true positive rate) of around 93 percent and specificity (1 — false positive rate) of around 95 percent. Further, a correlation study and analysis of variance were performed using the system assigned grades and the technician assigned grades, and these initial results are very promising.

Numerical Analysis of Fiber Fleece Behavior in Roller Drafting in a Transient State

Kim, J. S., Cherif, C., Huh, Y. — 2008-08-21

Fiber bundle thickness irregularity from a roll draft mechanism was analyzed in the time domain on the basis of a theoretical model (Partial Differential Equation, PDE, system) for bundle flow. As the governing equations that consisted of continuity and motion equations turned out to be nonlinear, being coupled between variables, etc., a numerical method was established to solve the problem. In particular, the Forward-Time Central-Space (FTCS) difference formula with an explicit Euler scheme as the Finite Difference Method (FDM) was applied. Then the system of equations, which were in algebraic form, was solved according to given initial and boundary conditions in an iterative fashion. Results from this research confirmed that the theoretical response of the output linear density to the disturbance of drafting condition agreed very well with experiment. The transient state of the velocity profile faded out more quickly than that of the linear density profile. The response of the output bundle thickness to the step change perturbation depended on process conditions or material properties. With certain model parameters, the disturbed linear density of the output sliver converged to a fixed value or had an increasing variation magnitude. This indicated that the characteristics of the output bundle thickness could change according to the bundle properties or to the process conditions, which could induce unstable changes in thickness.

Effect of Heating Rate on the Chemical Reaction during Stabilization of Polyacrylonitrile Fibers

Yongping Hou, , Tongqing Sun, , Haojing Wang, , Dong Wu, — 2008-08-21

The influence of the heating rate on the stabilization process of polyacrylonitrile (PAN) fibers was studied. The results show that with an increase in heating rate, the density and oxygen content show a continuous decrease. As a result, the strength continues to increase and the skin-core structure becomes more evident. However, the amount of shrinkage and the conversion index (A_I) are lowest at 5°C/min. On the basis of these observations, we conclude that at a heating rate lower than 5°C/min the intramolecular cyclization is the main reaction and its extent decreases with an increase in heating rate. Above 5°C/min, an intermolecular cross-linking reaction becomes more obvious and increases with an increase in heating rate.

Electrospun Nanoporous Fiber

Yue Wu, , Yu, J.-Y., Chi Ma, — 2008-08-21

Different concentrations of PBS/CF solution were prepared by dissolving Poly(butylenes succinate) (PBS) in Chioroform (CF) solvent. Single electrospun nanoporous fiber with an ultra-high specific surface was formed from electrospinning PBS/CF solution in a single processing step. As the concentration of PBS in CF increased, morphology evolved from beads only to ultra-fine continuous fibers. At a suitable concentration, PBS/CF 13%(w/w), uniform nanoporous threads of polymers were emitted from the jet by an electrospinning process. The electrospun nanoporous fibers were fabricated with average porous diameters of ~200 nm. The electrospun PBS fibers offer the potential for direct fabrication of biologically based, high-surface-area porous fibers without the use of multiple synthetic steps or post-processing surface treatments.

Study on Reduction of Air Consumption on Air-jet Weaving Machines

Goktepe, O., Bozkan, O. — 2008-08-21

As is well known, the main disadvantage of air-jet weaving machines is their high energy costs compared to projectile and rapier weaving machines. This makes air-jet looms less preferable for companies in countries such as Turkey that suffer from very high energy costs, despite their higher production speeds. Air-jet weaving loom manufacturers have continuously been working on the reduction of air consumption in their new designs to overcome this drawback. However, weaving mill practices are as important as machine designs on air consumption. In this study, therefore, we aim to investigate the possibilities to reduce air consumption on current air-jet weaving looms without making a new investment in a weaving mill. A decrease of air consumption by 21% was accomplished in a weaving mill by just decreasing the hole diameter of the single-holed relay nozzles and by optimizing the blowing time of the multi-holed relay nozzles. Thus, a company having 202 looms could save 240,000 per year in electricity costs with almost no expense. This paper explains the experimental work conducted in the weaving mill to minimize air consumption on air-jet looms.

Electromagnetic Shielding Effectiveness of Multifunctional Metal Composite Fabrics

Roh, J.-S., Chi, Y.-S., Tae Jin Kang, , Nam, S.-w. — 2008-08-21

The growth of the electronic industry and the widespread use of electronic equipment in communications, computations, automations, bio-medicine, space, and other purposes have led to many electromagnetic interference (EMI) problems as systems operate in close proximity. It is likely to become more severe in the future, unless proper EMI control methodology and techniques are used to meet the electromagnetic compatibility requirements. This article presents a comprehensive review of EMI shielding theory and materials. Furthermore, a method for fabricating a multifunctional metal composite fabric with electromagnetic (EM) shielding characteristics was successfully developed. The parameters influencing EM shielding properties of the metal composite fabrics were investigated. It was shown that the EM shielding effectiveness of the metal composite fabrics could be tailored by modifying the metal grid size and geometry.

Abstracts: Sen'i Gakkaishi, Vol. 64, No.9

2008-08-21

Future Events

2008-08-21

The Use of Textile Materials to Design Wearable Microstrip Patch Antennas

Hertleer, C., Tronquo, A., Rogier, H., Van Langenhove, L. — 2008-08-04

So-called "wearable textile systems" are intended to improve the quality of life by enhancing the wearer's functionalities. Garments having the ability to monitor biosignals and communicate with the environment can, for example, provide continuous information about a person's state of health. These data can be valuable medical input, but also in emergency operations such as fire extinguishing, it can be a tool to decide on the operability of the fire fighter. However, wireless communication with the environment requires antennas. When preserving textile properties such as flexibility and comfort is an issue, antennas should be made fully integratable into garments and, thus, manufactured from textile material. This paper shows the feasibility of the use of textile materials in the design of antennas working in the dedicated 2.45 GHz frequency range. We used a commercial electromagnetic field simulator to design microstrip patch antennas fabricated from both conductive (electrotextiles) and nonconductive textile material. For the antenna and the ground plane, readily available electrotextiles were assessed: FlecTron^®, Shieldit^TM Super and Zelt , while a fleece fabric was used for the antenna substrate. We found that such antenna prototypes had an efficiency of more than 75 %, which was comparable to conventional non-textile antennas. This research is an initial step in designing textile antennas and paves the way for a new generation of communicating garments.

Basic Studies for Modeling Complex Weft Knitted Fabric Structures Part IV: Geometrical Modeling of Miss Stitches

Kayacan, O., Kurbak, A. — 2008-08-04

In this work a model of miss stitch and its effect on the plain knitted fabric structure are introduced for the first time, thus we present a pioneering basic work on knit and miss combinations. Photographs of knitted samples were taken and the assumptions of the model are based on these photographs. A geometrical model of this knit and miss combination is created and the model is drawn to scale. We show that these shapes are found to be exactly the same shapes as observed in real fabrics.

Warp Break Detection in Jacquard Weaving Using Micro-Electro-Mechanical Systems: Effect of Yarn Type

Seyam, A.-F. M., Jin Ho Lee, , Hodge, G., Oxenham, W., Grant, E. — 2008-08-04

This paper reports a study aimed at detecting warp breaks in terms of yarn type using a Micro-Electro-Mechanical Systems (MEMS) accelerometer based detection system, which has been described in earlier publications. The MEMS accelerometers were mounted on harness cords of a Jacquard tie. MEMS output acceleration signals were analyzed. The signals were acquired while warp ends were up and at the moment of intentional break with a pair of sharp scissors simulating missing warp ends. The results indicated that MEMS acceleration signals at intentional breaks for continuous filament from standard and high strength fibers could be detected. The break signals of cotton and cotton/polyester spun yarns were undetectable.

Torque Due to Applied Tension in Ring-spun Yarns

Phillips, D. G. — 2008-08-04

A previous study showed that the torque in worsted wool yarns could be measured directly when the yarns were in the form of a hank under tension and that the torque could be split into two components, (a) the torque due to the applied tension and (b) the intrinsic torque at zero tension. This approach was applied to analyze the torque due to tension for a wide range of ring-spun worsted wool yarns of different structural parameters including yarn count, yarn twist and fiber diameter. The torque due to tension was measured on unsteamed and steamed yarns in dry and wet conditions and the data analyzed by applying mechanical models of yarn torque to estimate the yarn packing fraction. By using an effective linear density to evaluate the torque data, an estimate of the packing fraction of 0.63 allowed prediction of the torque in worsted wool yarns prepared from 18 to 24 micrometer diameter fibers across a wide range of yarn counts (16—80 tex) and wet and dry test conditions, and this approach was tested on some representative commercial wool worsted yarns. The effect of setting of worsted wool yarns on the torque due to applied load and the packing fraction was also identified and setting was shown to have little effect on the yarn torque due to tension.

A Study of the Twisted Strength of the Whirled Airflow in Murata Vortex Spinning

Zhuanyong Zou, , Longdi Cheng, , Wenliang Xue, , Jianyong Yu, — 2008-08-04

In Murata vortex spinning, the highspeed whirled airflow twists the open-end trailing fibers converged at the inlet of the hollow spindle into a yarn. The twisted strength acting on the vortex spun yarn by the whirled airflow was investigated by an analytical model based on simulating the flow field inside the nozzle block. The results showed that the twisted strength acting on the vortex spun yarn by the vortex could be regarded as the following functions: (1) the number of jet orifices, the jet angle, the inner diameter of the jet orifice and the nozzle block; (2) the distance from the inlet of the nozzle block to the inlet of the hollow spindle; (3) the projecting height of open-trail-end fibers twined over the top exterior of the hollow spindle; (4) the vortex spun yarn diameter; and (5) the velocity at exit of the jet orifice (i.e. corresponding to nozzle pressure). Increasing the velocity at exit of the jet orifice increased the strength twisted by the whirled airflow. The strength twisted by the whirled airflow increased with decreasing inlet diameter of the nozzle block, and was enhanced with increasing outer diameter of the hollow spindle. The strength twisted by the whirled airflow was weaker when the distance from the inlet of the nozzle block to the inlet of the hollow spindle was bigger. The numerical results validated the effectiveness of the analytical model.

Fiber Length Distribution in Cotton Processing: A Finite Mixture Distribution Model

Krifa, M. — 2008-08-04

This paper introduces a new approach to modeling and parameterizing cotton fiber length distribution. The approach uses finite mixture models to derive a parametric expression of the fiber length probability density function. The model was applied to a multitude of empirical length distributions and proved to adequately parameterize the complex distribution patterns, as well as express the intrinsic and process-related factors determining their shape.

Determination of Yarn Interlacing Frequency of Triangular Interlacing Nozzles through a Compressible Flow Simulation

Chau, S.-W., Liao, W.-L. — 2008-08-04

A numerical approach to predict the yarn interlacing frequency of triangular interlacing nozzle is discussed in this paper. The inviscid, compressible flow field inside air nozzles is computed through solving the steady continuity, momentum and energy equations with a finite volume method. A mathematical model for the prediction of yarn interlacing frequency of air nozzle is proposed, which is determined by the vorticity strength, air density, yarn density and yarn feed speed. The influences of inlet size, inlet pressure and inlet angle on the yarn interlacing frequency of an air nozzle series are studied. The numerical results are validated by experimental measurements and show good prediction accuracy for yarn interlacing frequency. The shock interaction inside the expansion chamber explains the nonlinear behavior of the yarn interlacing frequency curve under various operation conditions. For air nozzles only differing in their inlet diameter, an optimal size of inlet diameter can be attained for a given pressure. Insufficient or excessive size of inlet opening leads to a weak interaction of shock surface inside the expansion chamber, and results in a lower number of knots per unit length. For a given nozzle, an optimal inlet pressure can be obtained, which yields the largest yarn interlacing frequency per unit pressure. A minor increase in the yarn interlacing frequency is achieved for the inlet pressure greater than the critical pressure because the upper-lower shock surface has been completely developed. For air nozzles only differing in their inlet angle, an optimal inlet angle can be found at a given pressure, which seems insensitive to the inlet pressure. The proposed approach is proven to be effective and accurate in predicting the yarn interlacing frequency of air-jet nozzles, and also very promising for the design of air-jet interlacing nozzles to evaluate yarn interlacing frequency under different working conditions.

Particle Release from Woven Cellulosic Substrates

Manian, A. P., Lenninger, M., Bechtold, T., Steinlechner, E. — 2008-08-04

The linting propensity of a woven cellulosic substrate is investigated as a function of substrate characteristics and of different parameters in the test environment. The results from the linting propensity tests parallel those observed in liquid—solid extraction processes, where solutes are extracted from a matrix of other insoluble solids by selective dissolution in a liquid. The equation quantifying solute extraction in such systems also proves to be a good fit for the linting propensities observed in this work. Hence, it maybe possible to regard linting phenomena as extraction processes and to use the equation quantifying solute extraction to predict substrate linting as a function of both substrate characteristics and the test environment.

Comparison of Ballistic Performance and Energy Absorption Capabilities of Woven and Unidirectional Aramid Fabrics

Karahan, M. — 2008-08-04

This study investigated and compared the performance of ballistic protection panels formed with 100% woven and 100% unidirectional nonwoven para-aramid fabrics at different fabric ply numbers. For this purpose, Twaron CT 710 type woven para-aramid fabric panels and K-Flex unidirectional nonwoven para-aramid fabric panels (which were formed by using Kevlar 129 yarns) of different ply numbers were subjected to ballistic tests according to NIJ standards. Ballistic performance of the test samples was determined by measuring trauma depth and trauma diameter. The energy absorbed by fabric layers and the energy transmitted to the back of fabric layers were calculated from trauma depth and trauma diameter values. It was shown that the unidirectional fabric panels absorbed around 12.5—16.5% more energy than woven fabric panels for the unit panel weight.

Modern Applications of Nanotechnology in Textiles

Sawhney, A.P.S., Condon, B., Singh, K.V., Pang, S.S., Li, G., Hui, D. — 2008-08-04

Nanotechnology (NT) deals with materials 1 to 100 nm in length. At the National Nanotechnology Initiative (NNI), NT is defined as the understanding, manipulation, and control of matter at the above-stated length, such that the physical, chemical, and biological properties of the materials (individual atoms, molecules, and bulk matter) can be engineered, synthesized, and altered to develop the next generation of improved materials, devices, structures, and systems. NT at the molecular level can be used to develop desired textile characteristics, such as high tensile strength, unique surface structure, soft hand, durability, water repellency, fire retardancy, antimicrobial properties, and the like. Indeed, advances in NT have created enormous opportunities and challenges for the textile industry, including the cotton industry. The focus of this paper is to summarize recent applications of NT as they relate to textile fibers, yarns, and fabrics.

Sen'i Gakkaishi, Vol. 64, No.8

2008-08-04

Future Events

2008-08-04