Water Vapour Permeability Of Fabrics Research Articles

The influence of yarn parameters on thermo-physiological comfort of cotton woven fabrics

As the global temperature increases over time due to different environmental pollutions, apparel clothing with excellent thermo-physiological comfort needs to be developed to improve human health and comfort. Thermo-physiological comfort of apparel clothing must be suitable for the wearer both in winter and summer seasons. Poor thermo-physiological properties can lead to discomfort, fluctuation in body temperature, poor sweat management during wear and can affect human health as well as work efficiency. For this reason, optimum thermo-physiological comfort of clothing is a prerequisite for users at any given weather. The aim of this study was to investigate the effect of cotton yarn parameters on thermo-physiological comfort of woven fabrics. Four types of woven fabrics were developed from cotton yarn with different counts, twist, coefficient of variation of mass (CVm), neps, hairiness, thin places, thick places, strength and elongation. Yarn samples were produced separately by carding and rotor spun before they were woven on an air jet machine with same settings. Finally, the woven fabrics were finished in a combined finishing treatment process. Thermal resistance, thermal conductivity, thermal absorptivity, thermal diffusivity, air permeability and relative water vapor permeability of the woven fabrics were measured and analyzed. Statistically analyzed results showed that thermal resistance, thermal conductivity, thermal absorptivity and air permeability of fabrics had statistically significant change with P-values of .029, .035, .005 and .000, respectively. However, from the results, the yarn parameters did not affect thermal diffusivity and water vapor permeability of fabrics. Model equations were developed based on the results to predict the comfort of the fabric from the yarn parameters.

Some open questions of evaluation of comfort properties of functional clothing

In the paper, several relatively new aspects of testing of functional clothing are discussed, such as the effect of moisture and testing time on water vapour permeability of fabrics as well as the effect of the testing time on thermal resistance value of fabrics tested in Skin Model type testers. Also the difference between thermal resistance and thermal absorptivity of fabrics was explained. It was concluded, that there are still some unsolved problems in the above areas, which should attract the attention of textile scientists and technologists.

Moisture and Thermal Transport Properties of Different Polyester Warp-Knitted Spacer Fabric for Protective Application

Abstract Warp-knitted spacer fabrics are generally used for sportswear, functional clothing, protective clothing, and other applications. This article studied the heat and mass transfer properties of polyester warp-knitted spacer fabrics from low thickness (2 mm) to high thickness (20 mm), from low mass (247.34 g/m2) to high mass (1,585.9 g/m2), and surface structure in plain or mesh construction. Water vapor permeability, air permeability, water absorption, and thermal insulation property were conducted to evaluate the spacer fabrics. The results revealed that with increasing volume density the water vapor permeability of spacer fabrics decreased, but the water absorption ratio increased. The water vapor permeability of fabrics increased when thickness decreased and volume density increased. It was further found that spacer fabrics with mesh worn nearby the skin and plain structure worn far from the skin could facilitate water vapor and air transmission. The difference of 8.82% for water vapor permeability and 14.19% for air permeability were found between testing mesh side up and down for the spacers (2.56 and 3.37 mm), respectively. Thermal insulation ratio was highly and significantly correlated with heat transfer coefficient at −0.958 and with thickness at 0.917. Thermal insulation ratio is highly and significantly correlated with air permeability at 0.941.

Evaluating the effect of spinning systems on thermal comfort properties of modal fabrics

In recent years the importance of clothing comfort became one of the most important feature of the fabrics. The aim of this study is to characterize thermal comfort properties of single jersey fabrics were knitted using 100% modal yarns which were spun in various types of yarn spinning methods such as ring spinning, compact spinning, rotor spinning and airjet spinning. Thermal comfort properties like air permeability, thermal resistance, thermal absorptivity and water vapour permeability of fabrics were tested. The results indicate that compact spinning technology will be appropriate for the summer climate casual wear.

Thermal and water vapor transmission through porous warp knitted 3D spacer fabrics for car upholstery applications

This paper deals with water vapor transmission and thermal properties of various warp knitted spacer fabrics. In this work, thermal and water vapor permeability of different spacer fabrics have been evaluated by varying the structure, areal density, thickness, type of raw materials, etc. The air permeability and water vapor transmission of the fabrics were measured using the Textest FX-3300 air permeability tester and PERMETEST. The thermal behavior of fabrics was evaluated by Alambeta instrument. Analysis of Variance (ANOVA) was performed using new statistical software in order to compare the influence of different fabric parameters on thermo-physiological behavior of samples. This study established that the raw materials, type of spacer yarn, density, thickness, and tightness of surface layer have significant influence on thermal conductivity in spacer fabrics. The parameters which mainly influence the water vapor permeability of these fabrics are porosity, density, and thickness. The empirical model for thermal conductivity calculation shows very high accuracy when compared with experimental results. The statistical model for spacer fabrics also predicts the thermo-physiological properties with very high accuracy. These findings are important requirements for further designing of spacer fabrics for car seats and back supports.

A new method for calibrating hygrometers.

In this study, a new method was proposed for calibrating hygrometers. The moisture permeation cylinder, which was used to measure the water vapor permeability of fabrics, was used to generate various levels of relative humidity. A dry nitrogen stream was employed to sweep the water vapor away. It was deduced that the relative humidity of the outgoing nitrogen stream was negatively correlated to the volumetric flow rate of nitrogen stream, i.e., the lower the volumetric flow rate, the higher the relative humidity. The hygrometer HMT 333 was chosen to measure the relative humidity of the outgoing nitrogen stream at five levels. The test data indicated that good agreement was observed between the measured humidity and the observed humidity from the Vaisala, Inc. Moreover, this method offers high sensitivity and fast response. Therefore, the relative humidity of the outgoing nitrogen stream can be used as a secondary humidity reference.

Effect of Outer Air Flow on Water Vapor Permeability of Fabrics with Different Yarn Densities

Effect of Outer Air Flow on Water Vapor Permeability of Fabrics with Different Yarn Densities

Influence of Shrinkage on Air and Water Vapour Permeability of Double-Layered Weft Knitted Fabrics

Water vapour permeability and transport depends on the properties of the fibre and knitted fabric structure. It was designed double-layered fabrics knitted in plain plating pattern whose inner side was made from synthetic fibres the PES, PA, PP, and Coolmax® (tetra-channel fibres by DuPont) which do not absorb moisture and on the surface of the wear – natural cotton and bamboo fibres which have good absorption properties. In the present research it was established that the air permeability of all fabrics after washing and drying cycle decreased. It occurred because of the influence of shrinkage during washing and drying under the impact of moisture, heat, and mechanical action. After washing and drying cycle, the water vapour permeability of fabrics knitted from bamboo and synthetic yarns blend decreased predominantly and became similar to fabrics knitted from cotton and respective synthetic yarns blend. The water vapour permeability of fabrics knitted from cotton and synthetic yarns blend decreased significant less. Depending on the knitting structure, the most decrease of water vapour permeability was estimated to the plain plated fabrics.DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2438

Study and Interpretation of the Mass Transfer Phenomena through Textile Structures in the Wet State

In last decades, increased attention is paid to comfort properties of textiles and garments. The most important parameters characterizing the called physiological comfort of textile structures are the evaporative resistance and water vapour permeability. Contrary to common textiles, protective and functional garments and, also some technical textiles, are also used in wet state, which affect their comfort properties. In this paper, PERMETEST commercial instrument is described, which provide reliable non-destructive measurement of evaporative resistance and water vapour permeability of fabrics in dry and wet state. By means of this instrument, evaporative resistance and water vapour permeability of cotton, polyester and cotton/polyester knitting fabrics, in the wet state, were experimentally determined and results were discussed. The effect of count yarn and composition of the above mentioned properties of these fabrics has been investigated as well. Some surprising results were achieved: with increasing fabrics moisture, the water vapour permeability also increases, especially with the presence of hydrophilic textile material.

Thermal Comfort Properties of Knitted Fabrics Suitable for Skin Layer of Protective Clothing Worn in Extreme Hot Conditions

Key words: Physiological comfort, knitted fabrics, protective clothing Abstract. Thermal comfort of clothing is associated with the thermal balance between human body and the environment, and also a balance between the body heat production and the heat loss. During work activities performed in extreme hot conditions, the body produces substantial amount of heat energy which leads to raised body temperature. As a result the body perspires in liquid and vapour form to reduce the increased temperature. When this perspiration is transmitted to the atmosphere, the body temperature reduces. Thus the garments worn next to skin should allow the perspiration and heat to easily pass through them; otherwise the result will be a significant discomfort of the persons working in extreme hot conditions. Therefore, thermal properties and water vapour permeability of the fabrics used for the next-to-skin layer of protective clothing are very important for the maintenance of physiological comfort of workers. In the present study physical parameters, air permeability, porosity, thermal and water vapour permeability of six commercially available knitted fabrics of different fibre blends, different and knitted structures suitable for skin layer garments of protective clothing worn in extreme hot conditions were evaluated. The influences of fabric physical parameters, and optical porosity on thermal conductivity and water vapour permeability of fabrics were determined and correlation coefficients were calculated between these variables.

Effects of Air Temperature, Relative Humidity, and Wind Speed on Water Vapor Transmission Rate of Fabrics

The primary environmental variables which influence the water vapor transmission rate of fabrics include air temperature, relative humidity, and wind speed. The combined quantitative effects of air temperature, relative humidity, and wind speed have been explored. The air temperature varied from 10 °C to 30 °C in 5 °C-intervals. The relative humidity ranged from 0% to 50%. The wind speed was from 0.1 m/s to 0.4 m/s. A new test method was employed to measure the water vapor transmission rate of four typical fabrics exposed under 120 conditions of combinations of relative humidity and wind speed with air temperature. The results showed that high air temperature, low relative humidity, and high wind speed led to high water vapor transmission rate. The exponential equations were obtained from the whole database based on the multiple nonlinear regression analysis, resulting in a generalized quantitative description of various effects on the water vapor permeability of fabrics. The prediction quality was good, as the regression equations provided high correlation coefficients and low standard errors of the estimate. The prediction values from the regression equations agreed well with the experimental results.

Comparison of Test Methods for Measuring Water Vapor Permeability of Fabrics

There are a variety of test methods in use to measure the ability of fabrics to transport water vapor. They vary with respect to construction mechanisms, test conditions, and measurement parameters. Five testing instruments plus a new test apparatus were employed to evaluate the water vapor transport properties of fabrics with low, medium, and high vapor permeability. The test results show that the desiccant inverted cup method generated the highest water vapor transmission rate, followed by the new method, the dynamic moisture permeation cell (DMPC), the inverted cup method, and the upright cup method. The statistical analyses indicated that the new method is in good agreement with other standard test methods. Most of the correlations between any two of the methods are strong, except the upright cup method. The new test method offers a short test time and calls for a small sample size.

A new test method for measuring the water vapour permeability of fabrics

The water vapour permeability of textile fabrics is a critical determinant of wearer comfort. Existing test methods are either time consuming or require large amounts of material. A new test apparatus was developed for characterizing the water vapour permeability of fabrics. An aluminium cylinder covered with waterproof and vapour permeable PTFE laminate is used for generating water vapour source on one side of the sample. A dry nitrogen sweep gas stream is used to carry water vapour away. The calculation of the rate of water vapour transmission across the fabric is based on the measurement of the relative humidity of the outgoing nitrogen stream. This new measuring apparatus offers a short test time and calls for a small sample size. The comparison measurements show that the test results correlated well with those obtained from ISO 11092 and ASTM E96. Therefore, this test method provides a new technique to accurately and precisely characterize the water vapour transport properties of fabrics.

Sweating guarded hot plate test method

The sweating guarded hot plate instrument, simulating the heat and moisture transfer from the body surface through clothing material to the environment, was designed for the measurement of thermal resistance and water vapor permeability of fabrics, relating to comfort characteristics of the garment. A number of factors govern the accuracy of the measurement, namely air velocity, leading edge effect, bubbles and wrinkles, membrane effect and so forth. The sweating guarded hot plate apparatus provides reproducible and repeatable results. This steady-state testing equipment, however, needs to be redesigned to assess the characteristics of fabric to transport heat and moisture under transient conditions.

An Apparatus Used to Investigate Condensation for Fabrics, Laminates and Films

A complete representation of the skin microclimate-fabric-environment includes the skin layer S, fabric F and outside environment E. Between the skin and fabric is the “clothing microclimate” M. Condensation occurring on the fabric's inner surface depends upon perspiration transfer from the human body through the clothing, which is determined by the properties of the fabrics. A new measuring apparatus, which conducted under computer control, described in this paper can be used to investigate whether condensation occurs on the fabrics. The measuring apparatus can be used to examine, record and display temperature and relative humidity simultaneously and permits rapid testing of small quantities of fabrics in a short amount of time. It is logical to use the apparatus described in this paper rather than the ASTM 96E-00 to investigate water vapor permeability of fabrics, especially condensation on the fabrics' inner surface.