Correlation of Air Permeability to Other Breathability Parameters of Textiles

In the field of textile comfort of smart textiles, the breathability of the material is very important. That includes the flow of air, water and water vapours through the textile material. All these experiments are time consuming and costly; only air permeability is much faster and economical. The research is performed to find correlation between these phenomena of breathability and to predict the permeability based on only the air permeability measurement. Furthermore, it introduces a new way of expressing the Ret (water vapour resistance) unit according to SI standards as it is connected with the air permeability of garments. The need to find a correlation between air permeability and water vapour permeability is emphasised in order to facilitate the assessment of clothing comfort. The results show that there is a strong relation between air permeability and water vapour permeability for most of the textile material.

Water vapour permeability of wood – remarks on cup method procedure and measured data of spruce wood

Although the water vapour permeability of wood has been determined many times, there can be found a wide spread of values even related to only one wood specie and its single anatomical direction. This spread can possibly be attributed to the measurement method itself, since the cup method often shows high inter-laboratory error. However, even if the measurement and evaluation processes are well performed and under control, there were found several factors that can still highly affect the resulting value – up to ca. 70 %. These factors are neither mentioned in standards, nor were found in other sources. This paper theoretically describes those factors and their possible impact to the final value of water vapour permeability. Paper also presents one particular measurement scheme and obtained data from four cup tests performed on spruce wood in transverse direction.

Influence of production on hemp concrete hygrothermal properties: sorption, water vapour permeability and water absorption

Hemp concrete is considered to be a carbon negative material. Hemp absorbs CO2 during the growth and lime needs CO2 for carbonation. The material, which has good thermal insulation properties, is used as a non-bearing wall material or plaster. For such use the hygrothermal properties of a material must be well known especially when indoor insulation is in focus. In the current study hemp concrete produced in two different ways was in focus and following the hygrothermal properties of hemp concrete as a building material were studied: water absorption (EN 1015-18), water vapour sorption (EN 12571), water vapour permeability (EN 12572) and thermal conductivity (EN 12667). The results of the study can be used in hygrotheramal calculations and modelling.

ELECTROSPINNING OF ANTIBACTERIAL POLYURETHANE/ZnO NANOFIBERS

In this study, it is aimed to produce and characterize antibacterial polyurethane (PU)/Zinc oxide (ZnO) nanofibers by electrospinning method. Firstly, polymer solutions were prepared at various ZnO concentrations such as 0, 0.2, 0.4, 0.6, 0.8, 1. Then solution properties (conductivity, viscosity, surface tension) were determined and analysed the effects of ZnO concentration on the solution properties. PU/ZnO nanofibers produced via electrospinning under the optimum process parameters (voltage, distance between electrodes, feed rate and atmospheric conditions). Finally, the nanofibers were characterized in terms of fibre morphology, thermal stability, permeability and antibacterial activity using SEM-EDS, DSC-TGA, water vapour permeability and disk diffusion methods. According to the solution results; it was observed that conductivity and surface tension decrease significantly with ZnO addition. On the other hand, solution viscosity increases as the ZnO concentration increases. From the SEM images, it has been seen clearly that average fibre diameter increases with ZnO concentration and incorporation of ZnO particles to the fibre structure was verified by SEM-EDS. According to the thermal analyse result, nanofibers begin to degrade between 271.94 ºC and 298.73 ºC. In addition, water vapour permeability increases as the ZnO concentration increase. Lastly antibacterial activity against gram negative (E.coli) and gram positive (S. aureus) was determined with specific zone diameter.

A RESEARCH ON THE BREATHABILITY PROPERTY OF BABY DIAPER BACKSHEET

Disposable breathable diapers are considered as one of the most important developments in diaper sector. Breathable diapers keep the child’s skin dry and provide a comfortable feeling to the child. Breathability of diapers is obtained by using the breathable back sheet layer which is the most outer layer that the diaper comprises. In this study, the effects of laminating and printing processes on back sheet material breathability are studied. For this aim, four types of back sheet samples namely; film, printed film, laminated film and printedlaminated film are tested for breathability. For breathability testing, water vapour permeability test was applied with two different test devices which principally operate in different ambient conditions. As a result of the study, it is seen that, the breathability of back sheet component decreases as a result of printing and laminating processes. Also, it can be concluded that the ambient conditions for standard textile fabrics is not convenient for testing back sheet samples. Since, the test does not simulate the real ambient conditions of microclimate between the diaper and the child’s skin during diaper use.

Hygrothermal simulation of building performance: data for Scottish masonry materials

Retrofitting thermal insulation to solid masonry walls alters their hygrothermal behaviour, which can be modelled by hygrothermal simulation software. However, such software needs values of key material properties to ensure satisfactory results and until now data has not been available for Scottish masonry buildings. This work aims to contribute to a Scotland-specific dataset of material properties for use by designers working on such buildings. Thermal conductivity, water vapour permeability, sorptivity, water absorption coefficient, hygroscopic sorption, density and porosity were all determined experimentally for selected historic and contemporary masonry materials. Within the range of materials tested three groups of materials properties emerge. Natural hydraulic lime mortars, hot-mixed quicklime mortar and earth mortar all show comparatively low density, high porosity, low thermal conductivity, high water vapour permeability and variable but generally high hygroscopic sorption. Craigleith, Hailes and Giffnock sandstones, no longer available but obtained from conservation works on historic buildings, and Locharbriggs and Hazeldean sandstones, obtained from current production, all show intermediate values of these properties. Crathes granodiorite and Scottish whinstone (from current production) show high density, low porosity, high thermal conductivity, low water vapour permeability and low hygroscopic sorption. It is shown that these materials are all relevant to Scottish buildings constructed in traditional masonry and this paper presents the first comprehensive set of hygrothermal property data for them.

Thermal comfort properties of cotton/spandex single jersey knitted fabric

Knitted fabrics are characterized by comfort compared to woven fabrics due to their high extensibility and airpermeability, but they have lower dimensional stability after repeated washing especially single jersey knitted fabric(SJKF). Therefore, the spandex (Lycra) core-spun yarns are used to maintain the dimensions of knitted fabrics duringuse and after repeated stresses. In this study, nine elastic SJKF samples were produced at three levels of loop lengthand spandex percent using yarn linear density 30/1 Ne. For comparison, three 100% cotton knitted samples wereproduced with the same levels of loop length and yarn count. The dimensional and thermal comfort properties of thelong-stretch samples were compared with the short-stretch cotton knitted fabric. The thermal comfort properties (thermalconductivity, resistance, absorptivity, and water vapour permeability), air permeability, and dimensional properties weremeasured and compared to 100% cotton samples. The results showed that the stitch density, fabric density, fabricthickness, and thermal resistance increased, whereas the air, water vapour permeability, and spirality angle decreasedin cotton/spandex samples.

Functional Textile for Active Wear Clothing

Moisture management property is an important aspect of any fabric meant for active wear fabric, which decides the comfort level of that fabric specially used as active wear garments. Regular physical activity is important to maintain consistency in human health. To achieve comfort and functional support during various activities such as walking, stretching, jogging etc., athletes and sports persons use active wear clothing. A fabric’s moisture management performance is also influenced by its air and water vapour permeability. The moisture management finish (MMF) and Antimicrobial finish (AMF) have been used to increase moisture absorbency; improves wetting, wicking action and antimicrobial performance. In this study, influence of MMF and AMF finishes on the moisture management property of different knitted active wear fabrics had been carried out. For the study two different knit fabrics of 100% Polyester and 100% Nylon with three different GSM levels (100, 130 and 160) has been selected. Further two varieties of commercially available functional fabric finishes have been also taken for the study. The result shows that in case of finished fabric at certain concentration level, as the fabric GSM increases the value of Accumulative one-way transport index (OWTI) %, water vapour permeability but same time drying rate increases. The result shows that in case of finished fabric at certain concentration level, as the fabric GSM increases the value of accumulative one-way transport index (OWTI) %, water vapour permeability decreases but same time drying rate increases. The knitted fabrics of 100% Polyester and 100% Nylon composition follow the similar trend. Further with the increase of fabric finish concentration level, OWTI %, and water vapour permeability (WVP) factor decreases while the drying rate increases.

Permeability properties of woven fabrics containing two-ply fancy yarns

The basic intention of the presented research is to analyse the permeability properties of woven fabrics containing two-ply fancy yarns in the weft direction. Within the framework of presented research, two-ply fancy yarns were analysed. Because of their structure, they are classified as fancy yarns with structural effects. The first analysed two-ply fancy yarn is made of the mixture of 81% cotton and 19% viscose. The second is made of the mixture of 67% viscose and 33% flax. For the purpose of the presented research, woven fabrics containing two-ply fancy yarn were made in three different densities in weft (10 threads per cm, 13 threads per cm, and 16 threads per cm) in the twill weave T 1/3 Z. The theoretical part includes the historical development of the production of the fancy yarns, a detailed discussion of the ring production processes, the types and the structure of the fancy yarns, their use, and the global and European market of the fancy yarns. The experimental part consists of three parts. In the first part, the structural properties of the analysed fancy yarns were researched (the fineness of the fancy yarn, the frequency of repeating the effects per one meter of the yarn, the direction of twisting the fancy yarn, the number of the twists of the basic and the effective part, the diameter of the fibers, the diameter of the basic and the effective part, the fineness of individual components, the direction of the twist of individual components, and the percentage of the inside twist of individual components). In the second part, constructional properties of the analysed woven fabrics with the fancy yarn in the weft were researched (mass, thickness, the density of the warp and weft threads, and openness of the surface). In the third part, permeability properties of the analysed woven fabrics with the fancy yarn in the weft were researched where greater attention was paid to air permeability and water vapour permeability. The results of the research showed that the samples with the first two-ply fancy yarn in the weft (81% cotton and 19% viscose) have greater air permeability and water vapour permeability. Meanwhile, the samples with the second two-ply fancy yarn in the weft (67% viscose and 33% flax) have lesser abrasion resistance and poorer dimensional stability while being washed.