scholarly journals WATER VAPOR PERMEABILITY OF POROUS MEDIA

1959 ◽  
Vol 37 (4) ◽  
pp. 413-416 ◽  
Author(s):  
William Woodside
Keyword(s):  
Thermal Conductivity ◽  
Porous Media ◽  
Water Vapor ◽  
Permeability Coefficient ◽  
Lightweight Concrete ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Empirical Relationships ◽  
Glass Spheres ◽  
Cellular Concrete

Following the analogy between the laws of heat conduction and vapor diffusion, two theoretical expressions for the thermal conductivity of a composite medium are applied to the water vapor permeability coefficient of certain porous media. It is shown that both expressions reduce to a form very similar to the empirical relationships found by Penman and Edenholm for soils, glass spheres, charcoal, and cellular concrete. The calculation of the variation of water vapor permeability with density for a cellular lightweight concrete is illustrated.

THE USE OF FLY ASH ALUMINOSILICATE MICROSPHERES IN THE LIME DRY MIXES FOR FINISHING AERATED CONCRETE

2017 ◽  
Vol 2 (3) ◽  
pp. 6-8 ◽  
Author(s):  
Логанина ◽  
Valentina Loganina ◽  
Фролов ◽  
Mikhail Frolov
Keyword(s):  
Thermal Conductivity ◽  
Water Vapor ◽  
Fly Ash ◽  
Water Vapor Permeability ◽  
High Water ◽  
Vapor Permeability ◽  
Low Thermal Conductivity ◽  
Aerated Concrete ◽  
Sufficient Strength

The application of ash microspheres in lime dry construction mixtures, designed for finishing aerated. It is shown that on the basis of dry ash mixtures with microspheres characterized by coating a sufficient strength, low thermal conductivity, high water vapor permeability, resistance to the action of the slanting rain.

scholarly journals Organophosphorus Polyurethane Ionomers as Water Vapor Permeable and Pervaporation Membranes

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1442
Author(s):  
Ilsiya M. Davletbaeva ◽  
Oleg O. Sazonov ◽  
Ilyas N. Zakirov ◽  
Askhat M. Gumerov ◽  
Alexander V. Klinov ◽  
...  
Keyword(s):  
Water Vapor ◽  
Permeability Coefficient ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Polypropylene Glycol ◽  
Ionogenic Groups ◽  
Solute Content ◽  
Noticeable Increase ◽  
Pervaporation Membrane ◽  
Polyoxyethylene Glycol

Organophosphorus polyurethane ionomers (AEPA-PU) based on aminoethers of ortho-phosphoric acid (AEPA) were obtained and studied as pervaporation membrane materials for separating isopropanol/water mixtures. The regularities of the change in the water vapor permeability of AEPA-PU were also investigated. It has been established that an increase of solute content in the composition of the urethane-forming system and the content of ionogenic groups in AEPA leads to a noticeable increase in the vapor permeability of the resulting film materials. An increase in water vapor permeability values is accompanied by a significant increase in the pervaporation characteristics of AEPU-PU. It was shown that the conditions promoting clustering of phosphate anions cause an increase in the values of the vapor permeability coefficient of AEPA-PU obtained using polyoxypropylene glycol. However, the hydrophobicity of the polypropylene glycol surrounding the clusters makes it difficult for water to move through the polymer matrix. Due to the hydrophilicity of polyoxyethylene glycol, the highest values of water vapor permeability and pervaporation characteristics are achieved for AEPA-PU synthesized using PEG.

The effects of the combined process of enzymatic bleach clean-up, enzymatic defibrillation and dyeing on the comfort and physical properties of Tencel/cotton knitted fabrics

2019 ◽  
Vol 90 (9-10) ◽  
pp. 1118-1129
Author(s):  
Sibel Şardağ ◽  
Tuba Toprak ◽  
Pervin Aniş
Keyword(s):  
Thermal Conductivity ◽  
Water Vapor ◽  
Physical Properties ◽  
Water Vapor Permeability ◽  
Lower Surface ◽  
Air Permeability ◽  
Vapor Permeability ◽  
Knitted Fabrics ◽  
Single Bath ◽  
Loss Of Mass

This study aimed to investigate the comfort and physical properties of raw and finished knitted fabrics made of yarns with different Tencel/cotton blend ratios. For this purpose, Ne 20 yarns were produced with the same twist coefficient on the same production line. Fabric samples were produced on the same knitting machine. The raw fabrics were subjected to two different combined enzymatic pre-treatments and dyeing processes. In the first process, enzymatic defibrillation and dyeing were carried out in the same bath. In the second, enzymatic bleach clean-up, defibrillation and dyeing were conducted in the same bath. The comfort and physical properties of all the raw and finished fabric samples were measured according to the relevant standards. The results were assessed statistically. The results of this study showed that with increased percentage of Tencel in the blend, the water vapor and air permeability, fabric roughness, pilling, thermal absorption and loss of mass values of the fabrics increased, whereas thermal conductivity values decreased. It was observed that the fabrics which were subjected to enzymatic defibrillation and dyeing processes in a single bath gave lower surface roughness and abrasion values but higher air permeability values; while those subjected to enzymatic bleach clean-up, defibrillation and dyeing in a single bath gave higher thermal conductivity and thermal absorptivity values. Comparison of the two processes showed that there were no significant differences in the pilling and the water vapor permeability values obtained from both processes.

Novel method on thermal resistance prediction and thermo-physiological comfort of socks in a wet state

2020 ◽  
Vol 90 (17-18) ◽  
pp. 1987-2006 ◽  
Author(s):  
Tariq Mansoor ◽  
Lubos Hes ◽  
Vladimir Bajzik ◽  
Muhammad Tayyab Noman
Keyword(s):  
Thermal Conductivity ◽  
Water Vapor ◽  
Thermal Resistance ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Relative Water ◽  
Novel Method ◽  
Resistance Prediction ◽  
Filling Coefficient ◽  
Thermal Absorptivity

The present study proposes a novel method to measure the thermal resistance and comfort properties of various sock samples under wet conditions. Theoretically, comfort properties are responsible for transporting moisture by our body with different rates. Therefore, plain socks with different fiber composition were wetted to a saturated level and after getting the required moisture content, the sock samples were characterized by Alambeta (for thermal resistance and thermal absorptivity) and Permetest instruments for relative water vapor permeability in the wet state. In addition, various skin models were utilized to make a comparison of thermal resistance in the dry state. Two different models were modified for analyzing the thermal resistance under wet conditions. According to the models used, the prediction of thermal resistance is a combined effect of the filling coefficient and thermal conductivity of wet polymers instead of dry polymers. With these modifications, the used models predicted the thermal resistance at different moisture levels with a significant correlation ( R2) value, that is, 0.84–0.97.

Characteristics of Laminates for Car Seats

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Eva Batič ◽  
Dunja Šajn Gorjanc
Keyword(s):  
Thermal Conductivity ◽  
Water Vapor ◽  
Abrasion Resistance ◽  
Water Vapor Permeability ◽  
Areal Density ◽  
Air Permeability ◽  
Vapor Permeability ◽  
Car Seats ◽  
Basic Characteristics ◽  
Nonwoven Textiles

AbstractIn the presented research, 11 different laminates were compared, 8 of them were two-layered 3 of them were three-layered laminates. The laminates that were analyzed vary by the type of face-side textile material (knitted and nonwoven textiles), density and thickness of the foam, and specific properties (higher air permeability and low-emission foam). Depending on the different types of laminates, different laminating processes are used: hot-melt, flame, and powder laminations. The purpose of the presented research is to analyze the basic characteristics of the different laminate structures. Properties that are important for these types of laminates are the number of layers, areal density, thickness, resistance to rubbing, fire resistance, water vapor permeability, air permeability, breaking force and extension, thermal conductivity, and stratification. We found that the properties of laminates were not affected by the density and thickness of the foam. Nonwovens and other laminate components do not perform because they have lower abrasion resistance and lower tensile strength than knitted fabrics as the face layer. Knit laminates have good abrasion resistance, high air permeability, and water vapor permeability. Both are self-extinguishing to the first or second mark. Three-layered laminates have lower thermal conductivity and air permeability than two-layered laminates.

scholarly journals The Influence of Knitted Fabrics’ Structure on the Thermal and Moisture Management Properties

2011 ◽  
Vol 6 (4) ◽  
pp. 155892501100600 ◽  
Author(s):  
Elena Onofrei ◽  
Ana Maria Rocha ◽  
André Catarino
Keyword(s):  
Thermal Conductivity ◽  
Water Vapor ◽  
Water Vapor Permeability ◽  
Raw Material ◽  
Vapor Permeability ◽  
Structure Parameters ◽  
Knitted Fabrics ◽  
Moisture Management ◽  
Knitted Structure ◽  
Selection Of

This paper studies the influence of fabric's structure on the thermal and moisture management properties of knitted fabrics made of two types of yarns with thermo-regulating effect: Coolmax® and Outlast®. The main purpose of this study was the selection of the most adequate fabric, to be used in summer and winter sportswear. The results demonstrated that some properties, such as, thermal properties, diffusion ability, air and water vapor permeability are influenced by both raw material type and knitted structure parameters. Wicking ability is influenced to a greater extent by the knitted structure, while the drying ability is primarily determined by raw material and to a lesser extent by the knitted structure parameters. Outlast® fabrics are preferred candidates for warmer climate sportswear, particularly due to their lower thermal resistance, higher thermal conductivity and absorptivity, air and water vapor permeability. When considering sportswear for colder weather, Coolmax® based structures seem to be the best choice. These findings are an important tool in the design of a sportswear product tailored to the different body areas thermal and moisture management requirements.

Thermal comfort properties of weft knitted quilted fabrics

2020 ◽  
Vol 32 (6) ◽  
pp. 837-847 ◽  
Author(s):  
Sadaf Aftab Abbasi ◽  
Arzu Marmaralı ◽  
Gözde Ertekin
Keyword(s):  
Thermal Conductivity ◽  
Water Vapor ◽  
Thermal Resistance ◽  
Thermal Comfort ◽  
Water Vapor Permeability ◽  
Air Permeability ◽  
Vapor Permeability ◽  
Content Type ◽  
Thermal Comfort Properties ◽  
Thermal Absorptivity

PurposeThis paper investigates the thermal comfort properties of quilted (jersey cord) fabrics produced with different width of diamond pattern, different filling yarn linear density and different types of material.Design/methodology/approachA total of 12 fabrics were knitted by varying the width of diamond pattern (1 and 3 cm), the filling yarn linear density (300 and 900 denier) and the type of materials (cotton, polyester and their combination). In this regard, air permeability, thermal conductivity, thermal resistance, thermal absorptivity and relative water vapor permeability of these fabrics were measured and evaluated statistically.FindingsThe results showed that fabrics knitted using cotton yarn in both front and back surfaces exhibit higher thermal conductivity, thermal absorptivity and relative water vapor permeability characteristics; whereas samples knitted using polyester yarn in both surfaces have higher air permeability and thermal resistance. As the linear density of filling yarn increases, thickness and thermal resistance of the samples increase and air permeability, thermal conductivity, water vapor permeability characteristics decrease. When the effect of the width of diamond pattern compared, it is seen that an increase in the width of pattern lead to an increase in thickness and thermal resistance and a decrease in thermal conductivity, thermal absorptivity and water vapor permeability values.Originality/valueMany researches were carried out on the thermal comfort properties of knitted fabrics, however there is a lack of research efforts regarding thermal comfort properties of quilted fabrics.

Ultraviolet blocking and antioxidant polyvinyl alcohol films incorporated with baicalin extraction from Scutellaria baicalensis Georgi

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jinshu Liu ◽  
Xiaoyan Ma ◽  
Wenzhao Shi ◽  
Jianwei Xing ◽  
Chaoqun Ma ◽  
...  
Keyword(s):  
Water Vapor ◽  
Polyvinyl Alcohol ◽  
Radical Scavenging Activity ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Water Vapor Permeability ◽  
Scutellaria Baicalensis ◽  
Vapor Permeability ◽  
Protective Film ◽  
Uv Blocking

Abstract Baicalin, an active flavonoid ingredient of Scutellaria baicalensis Georgi, was extracted by heat reflux extraction and showed the same significance UV absorption property with standard baicalin. Active films were prepared from polyvinyl alcohol (PVA) containing baicalin extract by casting method. The effect of baicalin extracts on the UV-blocking, optical, antioxidant property, water vapor permeability, swelling and mechanical properties of the films were studied. UV–vis transmittance spectra showed that PVA films incorporated with baicalin extract blocked ultraviolet light range from 280–400 nm even with low concentration of baicalin (0.5 wt%) and maintain the high transparency in visible spectrum. The outstanding UV-blocking properties of PVA films incorporated with baicalin extract were also confirmed by Rhodamine B degradation. Baicalin conferred antioxidant properties to PVA films as determined by DPPH radical scavenging activity. Due to the interaction between hydroxy groups of baicalin and PVA molecule, water vapor permeability, swelling and elongation at break of the films were decreased accompanied with the increasing in tensile strength and Young’s modulus. FTIR reveal that the interaction between PVA molecules was significant changed by the introduction of baicalin. These results suggest that PVA film incorporated with baicalin extract can be used for the development of functional protective film.

scholarly journals The Effect of Extraction Conditions on the Barrier and Mechanical Properties of Kefiran Films

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 602
Author(s):  
Carmen Rodica Pop ◽  
Teodora Emilia Coldea ◽  
Liana Claudia Salanţă ◽  
Alina Lăcrămioara Nistor ◽  
Andrei Borşa ◽  
...  
Keyword(s):  
Water Vapor ◽  
Conformational Changes ◽  
Water Vapor Permeability ◽  
Edible Films ◽  
Film Structure ◽  
Water Soluble ◽  
Vapor Permeability ◽  
Water Molecules ◽  
Compact Structure ◽  
Technology Applications

Kefiran is an exopolysaccharide classified as a heteropolysaccharide comprising glucose and galactose in equimolar quantities, and it is classified as a water-soluble glucogalactan. This work aimed to investigate the effect of different extraction conditions of kefiran on the structural and physical properties of the edible films obtained. Fourier-transform infrared spectroscopy and scanning electron microscopy were performed, together with a determinations of moisture content, solubility, water vapor permeability and degree of swelling. The kefiran films presented values of the water vapor permeability between 0.93 and 4.38 × 10−11 g/m.s.Pa. These results can be attributed to the development of a more compact structure, where glycerol had no power to increase the free volume and the water vapor diffusion through their structure. The possible conformational changes in the kefiran film structure, due to the interspersing of the plasticizers and water molecules that they absorb, could be the reason for producing flexible kefiran films in the case of using glycerol as a plasticizer at 7.5% w/w. Moreover, it was observed that the extraction conditions are a significant factor in the properties of these films and their food technology applications.

scholarly journals Development of PE/PCL Bilayer Films Modified with Casein and Aluminum Oxide

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3090
Author(s):  
Anita Ptiček Siročić ◽  
Ana Rešček ◽  
Zvonimir Katančić ◽  
Zlata Hrnjak-Murgić
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Water Vapor ◽  
Aluminum Oxide ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Mechanical And Thermal Properties ◽  
Oxide Compound ◽  
Bilayer Films ◽  
Oxide Particles

The studied samples were prepared from polyethylene (PE) polymer which was coated with modified polycaprolactone (PCL) film in order to obtain bilayer films. Thin PCL film was modified with casein/aluminum oxide compound to enhance vapor permeability as well as mechanical and thermal properties of PE/PCL films. Casein/aluminum oxide modifiers were used in order to achieve some functional properties of polymer film that can be used in various applications, e.g., reduction of water vapor permeability (WVTR) and good mechanical and thermal properties. Significant improvement was observed in mechanical properties, especially in tensile strength as well as in water vapor values. Samples prepared with aluminum oxide particles indicated significantly lower values up to 60%, and samples that were prepared with casein and 5% Al2O3 showed the lowest WVTR value.

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