scholarly journals DEVELOPMENT OF MULTILAYER TEXTILE STRUCTURES FOR FILTERING APPLICATIONS – A NEW SURGICAL MASK APPROACH

2021 ◽  
Vol 2021 ◽  
pp. 26-34
Author(s):  
R.V. Costa ◽  
C. Silva ◽  
T. Sousa ◽  
J. Bessa ◽  
F. Cunha ◽  
...  
Keyword(s):  
Water Vapour ◽  
Vapour Permeability ◽  
Water Vapour Diffusion ◽  
Surgical Masks ◽  
Community Transmission ◽  
Substrate Resistance ◽  
Level I ◽  
New Generation ◽  
The Web ◽  
Governmental Strategy

Universal mask use has emerged as one of the main strategies for reducing community transmission of the SARS-COV-2 virus. Due to the scarcity of material to produce disposable surgical masks, the governmental strategy was oriented to the community masks, even though performance levels were still not the same. This study intended to develop a new generation of surgical masks with different warp knit structures, evaluating the potential of multilayer gradient performance. The assembling methodology was also considered by modifying flat-bed calendering process parameters and manipulating final structures into a new origami design concept, and the overall mask filtration performance was reviewed. The overlapping of monolayers increased the substrate resistance to air and water vapour permeability, also influencing the water molecule's adhesion. The introduction of the web allowed a better layer assembling during the flat-bad process. Moreover, the breathability and water vapour diffusion are compromised since the adhesive web with temperature tends to merge and occupy the empty spaces between the layers. Moving forward, calendared structures without a web proved to be the best approach, meeting the certification criteria for surgical masks level I and II.

scholarly journals THE IMPACT OF EXTERIOR FINISH VAPOUR RESISTANCE ON THE MOISTURE STATE OF BUILDING WALLS

2007 ◽  
Vol 13 (1) ◽  
pp. 73-82 ◽  
Author(s):  
Jolanta Šadauskienė ◽  
Edmundas Monstvilas ◽  
Vytautas Stankevičius
Keyword(s):  
Water Vapour ◽  
Mineral Wool ◽  
Water Vapour Permeability ◽  
Vapour Permeability ◽  
Exterior Surface ◽  
Paint Coating ◽  
Water Vapour Diffusion ◽  
Moisture State ◽  
Building Walls ◽  
The Impact

At present, when the building walls covered with a painted thin render are insulated by the mineral wool slabs from outside, the defects caused by the condensed moisture accumulated in the envelopes become more and more frequent. Water vapour permeability of the exterior finish (ie the paint), if compared with the water vapour permeability of the mineral wool slab, is rather small. That is why the paint coating may become the barrier for the water vapour diffusion and thus create favourable conditions for moisture accumulation in the exterior layers of the envelope during cold seasons. As a rule, to eliminate the defects, the exterior surface is repainted on the former paint coating because the render is thin and mechanically easily damaged. Repainting the thin render surface causes the following: 1) an increase of the exterior coating's vapour resistance; 2) a growth of the condensation intensity in the envelope exterior layers during the of moisture accumulation; 3) a decrease of the durability of the render‐paint system. The restrictions for the envelope exterior layer sd have already been recommended to employ in the European Union. Since moisture accumulation inside the wall is determined by the local climate, it is important to find out whether the recommendations concerning the given sd value might be applied for the exterior layers of the building walls in Lithuania. To find it out, the calculations of the envelope state and laboratory experiments have been carried out. The paper aims at the analysis of the impact of vapour permeability and its properties in the exterior layers of the wall on the envelope moisture state. It has been determined that the increase of the sd value is disproportionate to the number of the paint layers or the thickness of the paint coating. It has also been determined that the increase of the sd value forms the pre-conditions for the increased moisture amount under service conditions caused by water diffusion and condensation. The experiments revealed that, under Lithuanian climatic conditions, in the exploited building walls the sd value of the exterior layer of the thin render should make sd < 0,5 m and sd < 0,6 m in the paint coating.

Untersuchungen zum Diffusionswiderstand von Holzwerkstoffen | Diffusion resistance of timber materials

2005 ◽  
Vol 156 (3-4) ◽  
pp. 100-103
Author(s):  
Rudolf Popper ◽  
Peter Niemz ◽  
Gerhild Eberle
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Middle Lamella ◽  
Solid Wood ◽  
Diffusion Resistance ◽  
Water Vapour Diffusion ◽  
Wood Panels ◽  
Vapour Diffusion ◽  
Wet Climate ◽  
Panel Thickness

The water vapour diffusion resistance of timber materials were tested in a wet climate (relative humidity ranging from 100%to 65% at 20 °C) and in a dry climate (relative humidity ranging from 0% to 65% and from 0% to 35% at 20 °c) with variation by relative humidity and vapour pressure gradient. The diffusion resistance of multilayer solid wood panels lies under or within the range of the solid wood (spruce), tending even to a lower range. This can be attributed to the loosely inserted middle lamella of the used solid wood panels, which were not correctly glued by the manufacturer. The diffusion resistance of the solid wood panels increases with decreasing moisture content and decreasing panel thickness, as well as with increasing water vapour gradient from 818 to 1520 Pa. There were clear differences between the tested timber materials. The diffusion resistance of particle composites is strongly dependent on the specific gravity. Due to laminar particles OSBs(Oriented Strand Boards) have a larger diffusion resistance than chipboards. The water vapour diffusion resistance of OSBs lies within the range of plywood.

Using Control Chart to Detect Abnormal Changes in the Permeability

2013 ◽  
Vol 779-780 ◽  
pp. 319-322
Author(s):  
Ming Hung Shu ◽  
Jui Chan Huang ◽  
Thanh Lam Nguyen ◽  
Bi Min Hsu
Keyword(s):  
Water Vapour ◽  
Average Run Length ◽  
Stable Process ◽  
Critical Factor ◽  
Water Vapour Permeability ◽  
Control Signal ◽  
Process Mean ◽  
Vapour Permeability ◽  
Practical Applications ◽  
Printing Papers

Water-vapour permeability is a critical factor of writing/ printing papers in most of practical applications; but how to monitor the manufacturing process to keep the key characteristic of the paper in control is still understudied. Therefore, in this paper, in order to monitor the water-vapour permeability of writing/ printing papers, MaxGWMA chart is first suggested due to its best effectiveness in terms of average run length performance and its high capability of detecting small shifts in the process mean and variability as well as identifying the source and the direction of an out-of-control signal. By using MaxGWMA chart, assignable causes of any out-of-control signal should be deeply examined so as to have proper corrective actions undertaken to either eliminate them from the process or reduce the variability induced by them to make the papers consistently manufactured under a stable process.

Effects of exposure on water relations and photosynthesis of western hemlock in habitat forms

1976 ◽  
Vol 6 (1) ◽  
pp. 40-48 ◽  
Author(s):  
R. A. Keller ◽  
E. B. Tregunna
Keyword(s):  
Light Intensity ◽  
Water Content ◽  
Water Vapour ◽  
Western Hemlock ◽  
Diffusion Resistance ◽  
The Sun ◽  
Evaporative Demand ◽  
Photosynthetic Rates ◽  
Water Vapour Diffusion ◽  
Vapour Diffusion

Measurements of relative turgidity, transpiration rates, and photosynthetic rates on sun-grown and shade-grown western hemlock (Tsugaheterophylla (Raf.) Sarg.) were used to indicate effects of varying degrees of exposure.The sun-adapted form had low photosynthetic rates but maintained its water content under conditions of high evaporative demand. The shade-adapted form desiccated under exposed conditions, and in contrast with the sun-adapted form, its water vapour diffusion resistance decreased with increasing light intensity.

scholarly journals Evaluation of Bed Cover Properties Produced from Double Fabric Based on Honeycomb

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
A. A. Salama ◽  
A. S. El-Deeb ◽  
I. M. El-shahat
Keyword(s):  
Thermal Comfort ◽  
Water Vapour ◽  
Thermal Insulation ◽  
Abrasion Resistance ◽  
Air Permeability ◽  
Weft Yarn ◽  
Vapour Permeability ◽  
Geometrical Properties ◽  
Fabric Structure ◽  
Air Pockets

This research aims to innovate a new fabric structure, which could be used as a bed cover based on double honeycomb fabric with self-stitching. The honeycomb air pockets were aimed at facing each other to form closed small air chambers which work to sequester the air. The double fabric increases fabric thickness. Thus, the opportunity to improve thermal comfort could be achieved. A number of samples were produced with different densities and counts of weft yarn. Thermal insulation and water vapour permeability were measured and compared with bed covers produced from reversible weft backed structure. Geometrical properties, abrasion resistance, and air permeability were also measured. The results showed that the innovated structure had higher values of thermal insulation than reversible weft backed structure at certain weft counts and densities.

Sign in / Sign up

Export Citation Format

Share Document