Hiroko Yokura

Prediction of Fabric Bagging from Mechanical Properties

An objective evaluation method is proposed for predicting the bagging propensity of woven fabrics. The volume of the bagged fabrics was used as a measure of the bagging propensity. Dynamic creep caused by repeated shear deformation under con stant tension was measured in addition to the basic mechanical properties of fabrics. The correlations between the bagging volume of fabrics and their mechanical properties were examined statistically. For stretch fabrics, the bagging volume was correlated strongly with hysteresis behavior in tensile, bending, and low angle shearing defor mation measured after wetting conditioning for 5 hours at 32°C and 90% RH and with the value of the strain at t = 0.1 minutes, &(0.1) from the dynamic creep test. For conventional fabrics, a strong correlation was observed between the bagging volume and the value of the strain &(0.1) as well as the creep rate kd from the dynamic creep test. The equations for predicting fabrit bagging were obtained by statistical analysis of the relationship between the bagging volume of fabrics and their mechanical prop erties.

Objective Hand Measurement of Nonwoven Fabrics Used for the Top Sheets of Disposable Diapers

This study investigates the objective hand evaluation of top sheet materials used for disposable diapers based on their mechanical and surface properties. Previous experience has shown that a system for mens suiting is also useful for other materials, so we have used this system to assess the hand of top sheet nonwovens in terms of three primary hand values (stiffness, smoothness, and fullness). The equations for the mens suiting hand are modified such that each of the mechanical parameters substituted into these equations is normalized by using the respective mean value and standard deviation of the top sheet nonwoven population. The objective hand value of the top sheets is derived using both the mens suiting and general nonwovens equations. The subjective hand of the top sheets is assessed by students, and the mechanical and surface parameters are measured with the KES-FB system. It is clear that the hand of the top sheet nonwovens can be predicted by the equation developed for general nonwovens, for which the calculated error is within the range of the standard deviation of the subjective hand value of each product. Correlations between the hand of the disposable diapers and calculated hand of its top sheet nonwoven are also examined. The primary hand value of smoothness of the top sheets serves as a useful indicator for estimating the diapers hand.

Evaluation of the Wetness of Pantiliners

This study makes an objective evaluation of the wetness of pantiliners based on their physical properties and a subjective evaluation of the wetness of commercially produced pantiliners, based on subjective hand evaluation tests and wear trials performed by female subjects. The heat, air, and water transport properties of the pantiliners were measured using the Kawabata Evaluation System for Fabric (KES-FB) system, while the subjective wetness of the samples was analyzed using physical parameters. The wetness of pantiliners could be predicted from the water transport property. Those pantiliners that were evaluated as wet showed a large maximum value of heat flux under the wet condition (qmax-wet). The qmax-wet value is one of the key parameters for evaluating the wetness of hygiene products.

Durability of Fabric Handle and Shape Retention During Wear of Men's Summer Suits

Fabric handle durability and shape retention during wear of mens summer suits were evaluated under both wear and simulation conditions, using the objective eval uation methods of handle and garment appearance based on the mechanical properties measured by the KES-FB. The simulation test was performed using the KES-F5 fatigue test machine. Shape retention during wear of a suit jacket tailored from fabric with a total appearance value ( TAV ) of 4.39 was superior to that of a jacket tailored from fabric with a TAV of 2.15. The decrease in the TAVs after the simulation test was less for those fabrics having a high TAV than those with a rather low TAV. The TAV of the fabrics can be used to characterize the appearance of a suit after wear. For the wool and wool/mohair blend fabrics, there was a linear relationship between the decrease in the total hand value after the simulation test and the increase in fabric hysteresis at low levels of shear strain (2HG) measured after the deformation test of 104 cycles along the weft direction. The fabrics with good handle durability showed a small increase in 2HG in the deformation test of 104 cycles.

Compression and Thermal Properties of Recycled Fiber Assemblies Made from Industrial Waste of Sweater Products

Two kinds of recycled fiber assemblies made from knitted sweaters fabrics are exam ined by measuring compression, thermal, and air resistance properties, and they are compared with a pure wool assembly and a wool-blend assembly. For recycled fiber assemblies, the initial volume for a constant weight and stiffness to compression process are smaller than those of other samples at the same apparent fiber density. The effective thermal conductivities of recycled fiber assemblies are smaller than those of wool fiber assemblies. Recycled fiber assemblies show larger specific air resistance than the other samples when the volume fraction is the same. A recycled fiber mass has a unique structure, that is, some yams extracted from fabrics remain in the fiber mass. These yams do not show any decrease in compression, thermal, and air permeability properties compared with commercial fiber assemblies. These crimped yams in the fiber mass contribute to softness at the high fiber density apparent in compression.

Objective hand evaluation of non‐wovens used for nappies

Describes an investigation into the hand of non‐wovens used for nappies under both dry and wet conditions. The mean score of the subjective hand assessments (THVsub) of dry nappy was correlated with their surface properties which are obtained using the single wire U‐shape sensor.

Durability of Hand in Spandex Blend Fabrics

The durability of hand in spandex blend fabrics (1% spandex-wool and 2% spandex-wool/pe blends) was evaluated by the wear test and the laboratory simulation test, using an objective evaluation method of fabric handle based on the mechanical properties measured by the kes-fb system. The simulation test was performed to simulate the fabric fatigue process in actual wear by means of the kes-f5 fatigue test machine and commercial dry-cleaning. From the wear test, the primary hand values of numeri (smoothness) and fukurami (softness and fullness) showed a greater decrease for the spandex blend fabrics than those for the worsted fabrics. From the simulation test, the total and primary hand values of numeri for the spandex blend fabrics decreased remarkably compared with those for the conventional fabrics. The surface abrasion of the spandex blend fabrics caused by the wear test was much greater than that of the worsted fabrics, and was confirmed by the simulation test results. From the changes in the mechanical properties caused by the simulation test, spandex blend fabrics appear to show extensive bagging, whereas wrinkle resistance is stronger than that of the conventional fabrics. The cross-sectional areas of the spandex-wool/pe blend core spun yarns increased significantly with the simulation test, with a comparable decrease of resilience in the tensile properties, in contrast with the worsted yarns. The structural modifications in fiber assemblies of the core spun yarns govern the increase in hysteresis components of both the fabric and yarn, and the degradation of fibers in the core spun yarns contributes to the deterioration of the spandex blend fabrics.

Non‐recovery of Futon Padding after Repeated Compression

Non‐recovery of wool Futon padding was investigated by compression and creep tests. Simulation tests are also carried out to use the minuter model Futon. Fibre crimp was found to be an important parameter to be considered in the non‐recovery of Futon. Futon padding which consists of crimpy fibre has large apparent fibre density and shows less reduction of thickness compared with those made from uncrimpy fibres. The moisture inside and outside the Futon has a large influence on the recovery process.

Objective hand measurement of nonwovens used for top sheet of disposable diapers

The objective hand evaluation of the top sheet materials used for disposable diapers has been investigated, with consideration given to aspects of both dermatitis and comfort. The objective hand evaluation system for mens suiting has been applied to assess the hand of top sheet nonwovens. The subjective hand of the top sheet nonwovens, separated from the disposable diaper product, was assessed by female students. It became clear that the hand of the top sheet nonwovens could be predicted by the equation developed for mens suiting, for which the calculated error was within the range of the standard deviation of the subjective hand value of each product. The correlations between the hand quality of the diaper and the mechanical properties of its top sheet nonwoven were also examined. The diapers with high total hand value (THV) of their top sheet nonwovens were estimated to have good hand under both dry and wet conditions.

Analysis of Mechanical Fatigue Phenomena in Wool and Wool Blend Suiting Fabrics

Fatigue phenomena in fabrics can be quantified by increases in mechanical hysteresis properties. Increase in the mechanical hysteresis properties of fabrics with wear are considered with respect to the structural modification of fiber assemblies, the increase in interfiber friction, and the changes in the mechanical properties and crimp of fibers. The crimp of both yams and fibers decreased due to considerable extension of the fabrics during wear; the yams became flattened, thus increasing the lateral pressure and contact region at yam crossover points in the fabrics. The shear torque parameter C 1, which represents the effect of interfiber friction, increased with wear. Increased interyarn and interfiber friction is considered to govern the increase in the hysteresis properties of fabrics with wear. The yield stress and strain of fibers for tensile and torsional properties decreased with wear. The removal of fiber scales and the ragged fiber surfaces after wear were observed using scanning electron microscopy. Mechanical degradation and decreased crimp of kid mohair and polyester fibers with wear were greater than those of coopworth fibers.