Wet Relaxation Research Articles

Effect of Tuck and Miss Stitch on the Geometrical Properties of Regenerated Cellulose Plain and Derivative Knit Structures

Abstract This study aimed to analyze the effect of tuck and miss stitch structures of regenerated cellulose fabrics like viscose, modal, Tencel, and bamboo. The fabrics were developed with the same stitch length and tightness factor and analyzed for their geometrical properties after dry and wet relaxation. The study results revealed that wet relaxation treatment showed more significant changes in the geometrical constant values (K) than the dry relaxation process. The highest wale density change was noted with cross miss stitch fabric and a maximum course density change noted for cross tuck samples after dry and wet relaxation. The differences in wale and course density were noted as statistically insignificant for the aforementioned structure after dry and wet relaxation (p > 0.05). However, in the case of stitch density, there is a statistical significance noted for the tested samples (p < 0.05). The maximum changes were noted in plain fabric followed by twill structure. The loop shape factor (Kr) value suggests higher distortion in the cross tuck fabric and after wet relaxation over dry relaxed samples followed by plain, twill, and miss stitch structures, and we also noted the relaxation process did not alter the loop shape factor (Kr) significantly between the dry and wet process (p > 0.05).

Thermo physiological comfort of single jersey knitted fabric derivatives

The main aim of this study is to determine the thermo-physiological comfort properties of single knit fabrics and their derivatives. As the Single Jersey knitted fabrics are the most widely used fabrics in the apparel sector, they have been selected for the analysis purpose. Derivatives of single jersey are developed and compared in order to understand the influence of structural variations. Physical properties e.g. thickness and areal density were evaluated for all knitted fabrics with 100% cotton yarn having three different yarn linear densities and after different stages of relaxation. Various thermo-physiological properties have been studied by changing the combed cotton yarn linear density as well as the structure of single knit fabric. Air permeability, thermal insulation and relative water vapor permeability of the fabrics were observed and investigated under wet relaxed states. It is determined that fabric physical properties are affected by changing yarn linear density and by the dry or wet relaxation stages. The percentage/number of tuck stitches (NTS), location of tuck stitches (LTS) and ratio of tuck to knit stitches (RTKS) have strong influence on physical and thermo-physiological properties of single knit fabrics, even though other knitting parameters remained the same.

Numerical analyses on compaction behavior of nonwoven glass fiber fabric

In this study, thickness of single- and multi-layer nonwoven glass fiber fabric in dry and wet state was monitored during compaction and relaxation periods under a pressure range of 2 to 200 kPa. The results were numerically analyzed via power-law model and strain energy calculation. The compaction behavior of three-layer dry fabric stack showed the highest fitness to the power-law modeling. The findings of the power-law model revealed the lack of nesting between adjacent layers and showed that the repeated compaction/relaxation practice and the presence of resin significantly increased the fiber content. The outcomes of the model also indicated: (1) multi-layer fabrics tend to be compressed more easily than single-layer fabric (2) wet fabrics and relaxation periods display higher stiffening index than dry fabrics and compression periods, respectively. The compaction and relaxation curves tracing different paths pointed that some of the compaction energy was absorbed by the fabric. Thanks to the friction mechanism between layers, multi-layer fabrics absorbed more compaction energy (i.e. relaxed better) than single-layer fabric. However, the presence of the resin reduced the relaxation (i.e. the amount of absorbed compaction energy).

Determining the loop length during knitting and dyeing processes

Loop length is one of the most relevant variables to control while producing knitted fabrics because the final characteristics of the finished fabric depend on it to a great extent. The procedure followed to calculate it is based on standard UNE-EN 14970, and it is cumbersome, time-consuming and requires yarn-measuring equipment. This study investigated several single jersey and 1 × 1 rib structures produced with different yarn counts and 100% cotton yarns, and a 1 × 1 rib structure that was half-plated in alternating courses by defining four relaxation states of the different fabrics: two knits (knitting and dry relaxation and knitting and wet relaxation) and two dyed (dyed and dry relaxation and dyed and wet relaxation). The most significant dimensional variables were characterized in all the relaxation states and models were presented that explain the variability of the yarn length absorbed by the loop using other variables that are much simpler to analyze.

Wet Relaxation of Electrospun Nanofiber Mats

Electrospinning can be used to produce nanofiber mats. One of the often used polymers for electrospinning is polyacrylonitrile (PAN), especially for the production of carbon nanofibers, but also for a diverse number of other applications. For some of these applications—e.g., creation of nano-filters—the dimensional stability of the nanofiber mats is crucial. While relaxation processes—especially dry, wet and washing relaxation—are well-known and often investigated for knitted fabrics, the dimensional stability of nanofiber mats has not yet been investigated. Here we report on the wet relaxation of PAN nanofiber mats, which are dependent on spinning and solution parameters such as: voltage, electrode distance, nanofiber mat thickness, and solid content in the solution. Our results show that wet relaxation has a significant effect on the samples, resulting in a dimensional change that has to be taken into account for nanofiber mats in wet applications. While the first and second soaking in pure water resulted in an increase of the nanofiber mat area up to approximately 5%, the dried sample, after the second soaking, conversely showed an area reduced by a maximum of 5%. For soaking in soap water, small areal decreases between approximately 1–4% were measured.

Influence of yarn folding on UV protection properties of hemp knitted fabrics

In the last years the media have highlighted the damage of the ozone layer and the resulting increase of ultraviolet radiation (UVR) reaching the earth?s surface. Prolonged and repeated, both occupational and recreational, sun exposure of the population causes some detrimental effects. Clothing is considered to be one of the most important tools for UV protection. It is generally accepted that synthetic fibres provide a high UV protection capability of textiles, while cellulose fibres (cotton, linen, hemp, viscose) have a low UV absorption capacity. However, natural pigments, pectin and waxes in natural cellulose fibers, and lignin in hemp fibers, act as UV absorbers having a favorable effect on UPF of grey-state fabrics. Bearing in mind the trend of reintroduction of hemp fibers as a source of eco-friendly textiles, there is a serious lack of study about the potential of hemp materials in terms of UV protection. Folded yarn is a complex yarn composed of two or more component yarns arranged parallel and twisted together to make a ?new quality? yarn. Folding of yarns is an operation undertaken in order to modify single-yarn properties to an appreciable degree. There are very few investigations concerning the relationship between the yarn properties and UV protection effectiveness of the fabric made there from. In addition, there is no any result in the scientific literature about the influence of yarn folding on UV protection properties of textile materials. Having this in mind, for our research the idea was to evaluate the effect of yarn folding in this regard. The plain knitted fabrics composed of single or two-folded hemp yarn were compared in terms of UV protection properties. The Ultraviolet Protection Factor (UPF), as the quantitative measurement of the material effectiveness to protect the human skin against UVR, was determined for the textile materials by in vitro test method according to the European standard EN 13758. The knitted fabrics construction and physical properties were also determined. Bearing in mind that plain knitted fabrics are particularly susceptible to relaxation, they were subjected to relaxation and shrinkage by wetting process, and testing procedure was repeated on the water-treated samples. The results obtained indicated that the folding operation influences UV protection properties of knitted fabrics through an influence on a loop configuration, i.e. the fabric openness. Relaxation and shrinkage of the knitted fabrics due to wet relaxation caused the reduction of macro-porosity increasing the UPF of the knitted fabrics. Although the knitted fabric produced from single hemp yarn was characterized by higher UPF, the UVR transmittance of the folded hemp yarn knitted fabric after wet relaxation placed it in the ?excellent UV protection category? (according to European Standard EN 13758-2). This fact together with the better thermal comfort manifested itself in higher air permeability, confirmed the potential of folding operation in terms of UV protection properties of textile materials.

The effects of TMP and filler stratifying on wet web runnability and end product quality of fine paper

Abstract Increase of filler content in paper improves quality of the final product and reduces raw material costs. However, this is often accompanied by deterioration of paper machine runnability. In this paper the effects of stratifying PCC (precipitated calcium carbonate) and TMP on fine paper quality and the mechanical properties of dry and wet paper were studied. In addition, a new method was introduced for evaluating the layer purity of pulp and filler stratifying by measuring the fibre length distribution in the thickness direction of the paper. The filler addition reduced the mechanical properties of paper more with chemical than mechanical pulps, with similar dry tensile indices. Stratifying filler onto paper surfaces gave higher dry tensile strength properties than samples with mixed structures, whereas only a small positive effect was detected for wet tensile and relaxation properties as a result of stratifying. Stratifying fillers only had a small negative effect on the internal bond strength. Stratifying or mixing TMP with a chemical pulp blend was shown to enable an increase in the filler content of 10% without significant changes in the residual tension (tension after 0.475 s of relaxation) or tensile index of wet samples. Based on layer purity analysis, stratifying TMP and filler was found to be successful in these trials.

Establishing the effect of loop length on dimensional stability of single jersey knitted fabric made from cotton/lycra core spun yarn

Munden and earlier workers established that in plain knitted fabrics the fabric dimensional parameters namely Kc, Kw and Ks are constant at dry and wet relaxed state for wool, cotton, orlon and nylon yarns. But in the present study of cotton/lycra core spun yarn single jersey derivative knitted fabrics the values for Kc, Kw and Ks varies with loop length. The ratio of Kc/Kw also varies with loop length. In this paper, Single jersey fabric is produced from Polyester/lycra aircovered yarn with different loop lengths. The study covers about the testing of dimensional properties of the single jersey knitted fabric. After the fabric production, the fabric was dry relaxed. Wales per inch, courses per inch, fabric width, loop length and fabric thickness are all measured. Then the fabric was wet relaxed and tested for the above parameters. Then the samples were heat set at various stretch levels at 180°C. From the study, it was found that the dimension of fabric shows considerable change during wet relaxation. The fabric shows very good appearance when heat set at all stretch levels at 180°C in course direction. The fabric with a loop length of 2.5 mm was found to have better appearance when compared to the fabrics of other loop lengths. In particular 10% stretch level shows a better appearance for 2.5 mm loop length. Keywords: Dimensional stability, dry relaxation, wet relaxation, cotton/lycra core spun yarn, loop length, single jersey knitted fabric.

Establishing the Effect of Loop Length on Dimensional Stability of Single Jersey Knitted Fabric made from Cotton/lycra Core Spun Yarn

Munden and earlier workers established that in plain knitted fabrics the fabric dimensional parameters namely Kc, Kw and Ks are constant at dry and wet relaxed state for wool, cotton, orlon and nylon yarns. But in the present study of cotton/lycra core spun yarn single jersey derivative knitted fabrics the values for Kc, Kw and Ks varies with loop length. The ratio of Kc/Kw also varies with loop length. In this paper, Single jersey fabric is produced from Polyester/lycra air-covered yarn with different loop lengths. The study covers about the testing of dimensional properties of the single jersey knitted fabric. After the fabric production, the fabric was dry relaxed. Wales per inch, courses per inch, fabric width, loop length and fabric thickness are all measured. Then the fabric was wet relaxed and tested for the above parameters. Then the samples were heat set at various stretch levels at 180°C. From the study, it was found that the dimension of fabric shows considerable change during wet relaxation. The fabric shows very good appearance when heat set at all stretch levels at 180°C in course direction. The fabric with a loop length of 2.5 mm was found to have better appearance when compared to the fabrics of other loop lengths. In particular 10% stretch level shows a better appearance for 2.5 mm loop length.

Dimensional stabilization of cotton plain weft knitted fabric using mercerization treatment

Investigation on dimensional stability of cotton plain weft knitted fabric manufactured from rotor spun yarn, subjected to mercerization treatment has been represented. Several fabric samples were mercerized considering variation in time of treatment, bath temperature, concentration of alkali solution and also mercerizing tension. Values of constant of course (Kc), constant of wale (Kw), the area geometry constant (Ks) which are indicative of fabric dimensional stability were calculated after treatment for mercerized samples. Then, these values were compared with those of un-treated samples subjected to dry and wet relaxation and also were compared with each other. Based on the effect of each variable itself and their simultaneous effect, it was concluded that, mercerization treatment and considered parameters had a distinctive influence on dimensional stability of the fabric. Mercerized samples had better dimensional stability in comparison with un-treated ones. A comprehensive experimental analysis showed that, there is meaningful difference between Ks values of the samples mercerized at various conditions. Also, the area geometry constant (Ks) achieved after treatment was higher than that of other relaxation methods.

Dimensional characteristics of core spun cotton‐spandex 1×1 rib knitted fabrics in laundering

PurposeThis paper aims to study the dimensional characteristics such as fabric density variations, dimensional constant parameters, linear and area dimensional changes and spirality angle variations of 1 × 1 rib knitted structures made from cotton‐spandex core spun yarns, under laundering regimes till 10th washing cycle.Design/methodology/approachSamples of the above fabrics underwent dry, wet and full relaxation treatments and were subjected to standard atmospheric conditions prior to take the measurements. Washing was done in a front loading machine under normal agitation with machine 56 RPM. Each washing regime includes wash, rinse, spin, tumble dry steps. Washing temperature was set at 40°C and water intake for washing was 30 l and rinsed with cold water. 0.1 g/l standard wetting agent was used. The mass of the load was maintained constant to 3 kg to keep the material ratio as 1:10. Washing regimes were continued till 10th cycle.FindingsCotton‐spandex rib structures came to a more stable state (minimum energy state) after 10th laundering cycle under the experimental conditions. Cotton did not come to such a state, even after 10th cycle proceeded. ANOVA analysis done under 95 percent confidential level has shown that fabric tightness and relaxation procedures give significant effect on dimensional characteristics of cotton‐spandex and cotton rib structures. However, area shrinkage variations of cotton rib fabrics have shown an exception to this.Research limitations/implicationsAccording to the dimensional constant values, evenafter 10th washing cycle, cotton rib structures did not come to a stable position. This should be further investigated to achieve a better stable rib knitted structure.Practical implicationsThe number of washing cycles can be increased or tumble dry duration can be increased to 120 min. to get a more stable state of cotton rib structures.Originality/valueThe results are important for the knitting industry to predict the dimensional behavior of designed knitted fabric under relaxation. These data can be used to set the circular machine parameters to achieve a more stable fabric after laundering.

Effects of Laundering on the Surface Properties and Dimensional Stability of Plain Knitted Fabrics

The effects of laundering and laundering temperatures on surface properties and dimensional stability are investigated for plain flat knit silk, cotton, and polyester fabrics with varying cover factors. The fabrics are subjected to relaxation processes and an extended series of wash and tumble-dry cycles in laundering baths of various tempera tures. Dimensions, surface friction, and roughness of the fabrics are measured in every process. Changes in dimensional stability and surface properties with relaxation processes and laundering temperatures are clarified. Relations between frictional motion and struc tural parameters are also discussed. The results reveal that the dimensional stability of silk is sensitive to a particular temperature. The highest shrinkage is recorded with slackly knitted cotton at the highest temperature. There is a considerable effect of wet relaxation on dimensional stability as well as surface properties. Silk's coefficient of friction is the highest, and the lowest surface friction for cotton occurs at the highest temperature. Slackly knitted fabrics also show higher friction than tightly knitted fabrics. The coeffi cient of friction has a tendency to decrease with increasing tightness, while the surface roughness shows an opposite tendency. There is a good correlation between stick-slip motion and ribs on the fabrics.

Dimensional Changes in Knitted Silk and Cotton Fabrics with Laundering

Deformation by laundering is investigated for single jersey and 1 × 1 rib flat knit silk and cotton fabrics with yams of varying linear densities and fabric tightness. The fabrics are subjected to relaxation processes and an extended series of wash and tumble- dry cycles. Changes in dimensions are measured in every process and cycle. Statistical analyses of the experimental data reveal the effect of yam type as well as linear density and tightness factor on the linear and area shrinkage behavior of silk as compared to cotton. Cotton shrinks more than silk, and silk rib knits stretch excessively in width. Silk attains full relaxation after one laundering cycle. Microscopic views reveal the appearance of ball-like formations along silk fibers after repeated laundering. It is possible to predict fabric dimensional changes with wet relaxation as well as with laundering, especially in silk.

Relaxation properties of non-equilibrium wet steam flows

Internal relaxation processes in wet steam flows through channels and nozzles are analysed basing on derived general equations describing non-equilibrium wet steam processes. Characteristic relaxation distances for single-deviation processes are determined and their application is discussed. As a synthetic intensity measure of complex multi-parameter processes a concept of entropy relaxation distance is introduced. Calculation methods of wet steam relaxation processes and thermodynamic loss determination are presented.

Measurement of Relaxation Shrinkage in Woven Wool Fabrics

Relaxation shrinkage in wool fabrics is normally measured after relaxation of the fabric in water or steam. Values obtained for relaxation shrinkage after wet relaxation depend on the manner in which the fabric is dried. If the wet fabric is dried directly in an oven, the values for relaxation shrinkage are low, but if the fabric is allowed to dry under ambient conditions before oven drying, values are high. Steaming procedures produce relaxation shrinkage values that are considerably lower than those obtained with wet relaxation. An interlaboratory trial conducted using thirteen commercial worsted fabrics has determined the repeatability and reproducibility of different meth ods for calculating the magnitude of relaxation shrinkage. The practical significance of the different methods has been assessed from garment trials where fabric shrinkage, resulting from making-up and from wear, was examined. A procedure for measuring relaxation shrinkage is recommended.

Electrochemically deposited polythiophene. 2. Dry and wet relaxation

polythiophene (PT) freshly electrodeposited at 1.9 V vs 0.01 M Ag + /Ag from 0.1 M thiophene +0.1 M tetrabutylammonium tetrafluoroborate (TBATFB)/acetonitrile is not in equilibrium either as an isolated phase or when it is in contact with the solution it was deposited from. Consequently, spontaneous relaxation processes take place during and after growth until equilibrium conditions are established. These simultaneous processes happen at very different speeds. Relaxation of the PT film begins already during its growth, electroneutrality or its bulk being ensured by the fast uptake or anions. If the fresh PT is quickly washed and then kept dry and electrically isolated, its electron work function decreases

Dimensional and Physical Characteristics of Single Jersey Fabrics

An account is given of a study of the dimensional changes of plain weft knitted fabrics made from 12s, 16s, and 22s grasicrimp yam, brought about by various processes of relaxation including dry relaxation, wet relaxation, and tumble drying. In the dry relaxed state, the nature of knitted loop depends on the yarn's physical properties and knitting variables. After full relaxation, the values Kc, Kw, Ks, and Kc/Kw are independent of yarn or machine variables and approach a constant. In the full relaxed state, fabric thickness is independent of the tightness factor and depends on yam diameter and twists. The angle of wale lines with the vertical is increased with the twist multiplier and further increases after wet relaxation. Fabric bulk depends on loop length in all states of relaxation and has a linear relationship with the tightness factor after full relaxation.

The Dimensions of 1 X 1 Rib Fabrics

Rib fabrics from cotton and cotton-blend yarns were treated to a variety of relaxation treatments. Cotton fabrics undergo greater wet relaxation shrinkage than synthetic fiber fabrics, while hot dry treatments have the opposite effect. Blends of cotton and synthetic fibers produce "u" values between high and low values of the 100% fabrics, while relaxation shrinkage is very fiber-sensitive. Consolidation shrinkage appears to be independent of the blend constitution of cotton polyester fabrics. Cotton rib fabrics attain similar "u" values to those reported for wool fabrics.

Comparison of Preshrinkage Treatments for Crosslinked Knitted Cotton and Cotton Blends

Laundry shrinkage in knitted fabrics of cotton or cotton-polyester was reduced by a combination of chemical cross-linking and preshrinkage treatments. Preshrinkage during finishing was induced by compression either before or after crosslinking, and by either wet or dry relaxation after crosslinking. The effects on fabric loss in processing, strength, fabric structure, and recovery from deformation were compared for each combination.

7—THE DEGREE AND STABILITY OF FLAT-SET IN WEFT-KNITTED COTTON FABRICS

The measurement of the couple–curvature parameters for weft-knitted fabrics by the use of a Shirley Bending-hysteresis Tester is described. Changes are shown in coercive couple, elastic rigidity, and bending recovery as a result of structural alterations because of finishing or wet relaxation. The degree of flat-set and the stability of flat-set depend upon obtaining a relaxed fabric whose internal energies are reproducibly minimal.