scholarly journals The use of an internal airtight membrane in CLT external wall in terms of hygrothermal performance

2021 ◽  
Vol 2069 (1) ◽  
pp. 012208
Author(s):  
V. Kukk ◽  
J. Kers ◽  
T. Kalamees
Keyword(s):  
Water Vapor Permeability ◽  
Stochastic Approach ◽  
High Water ◽  
Vapor Permeability ◽  
Diffusion Resistance ◽  
Mold Growth ◽  
External Wall ◽  
Hygrothermal Performance ◽  
Dry Out ◽  
The Impact

Abstract This study focused on the dry-out capacity of the vapor-permeable CLT (cross-laminated timber) external wall and the impact of using an internal airtight membrane. The results of the work were obtained first from the field measurements, after which the simulation model was created and validated, and the hygrothermal performance of the wall was analyzed by a stochastic approach. The results of this showed that the CLT dries out quickly and safely in a wall assembly with a high water vapor permeability, even with the large range of initial CLT MC (13-25%). When an additional airtight layer with high vapor diffusion resistance (Sd of 244 m) is added between the insulation and the CLT, the dry-out capacity of the CLT decreases significantly and there is a high probability of mold growth on the CLT surface. The risk of mold growth can be prevented when the vapor resistance (Sd) of the airtight layer is reduced to 1.5 m in a case where initial CLT MC is up to 25% and in a case where initial MC is up to 20%, the vapor resistance of an airtight layer must be reduced to 3 m.

scholarly journals On the importance of desiccant during the determination of water vapor permeability of permeable insulation material

2020 ◽  
Vol 172 ◽  
pp. 14003
Author(s):  
Thibaut Colinart ◽  
Patrick Glouannec
Keyword(s):  
Water Vapor ◽  
Building Materials ◽  
Wood Fiber ◽  
Construction Materials ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Diffusion Resistance ◽  
Insulation Material ◽  
The Impact

Water vapor permeability of building materials is usually measured using dry cup test according to the ISO 12572 standard. For this test, suitable adsorbing desiccant should be used to provide stable low vapor pressure conditions within the cup and, thus, to ensure the good accuracy of the measurement. In this work, different adsorbing desiccants mentioned in the ISO 12572 standard are tested for measurements performed on wood fiber insulation. For each experiment, relative humidity is monitored inside the dry cup. The results indicate that 0 %RH is not reached inside the dry cup and boundary condition is not always stable for highly permeable construction materials, depending on the adsorbing desiccants. The impact of these observation is evaluated on the determination of water vapor diffusion resistance factor and compared to other sources of uncertainties.

scholarly journals Influence of Fabric Weave on Thermal Radiation Resistance and Water Vapor Permeability

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 525
Author(s):  
Ana Kiš ◽  
Snježana Brnada ◽  
Stana Kovačević
Keyword(s):  
High Temperatures ◽  
High Performance ◽  
Thermal Protection ◽  
Water Vapor Permeability ◽  
Radiant Heat ◽  
The Body ◽  
Vapor Permeability ◽  
Weave Structure ◽  
Fabric Structures ◽  
The Impact

In this work, aramid fibers were used to develop new, high-performance fabrics for high-temperature protective clothing. The research was based on the impact of the weave structure on fabric resistance to radiant heat. The goals of the research were primarily related to the development of new fabric structures created by the weave structure, which gives better protection of the body against high temperatures in relation to the standard weave structures that are used today. According to the results obtained it can be concluded that the fabric weave significantly affects the fabric structure, which consequently determines the effectiveness of protection against high temperatures. The justification for the use of multi-weft and strucks weave structure, which provides greater thermal protection and satisfactory breathability than commonly used weave structures, was ascertained.

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.

HYGROTHERMAL PERFORMANCE ASSESSMENT OF ICF WALLS WITH DIFFERENT MOISTURE CONTROL STRATEGIES AND WALL DESIGNS

2017 ◽  
Vol 12 (4) ◽  
pp. 35-53 ◽  
Author(s):  
Emishaw Iffa ◽  
Fitsum Tariku
Keyword(s):  
Moisture Transfer ◽  
Control Strategies ◽  
Vapor Permeability ◽  
Transfer Model ◽  
Drying Process ◽  
Moisture Control ◽  
Hygrothermal Performance ◽  
Insulation Thickness ◽  
Insulated Concrete Forms ◽  
The Impact

The initial high moisture content of concrete and the low vapor permeability of insulation layers on both sides of the concrete complicate the drying process of Insulated Concrete Forms (ICF). In order to facilitate the moisture transport and enhance the drying process, different moisture control strategies and wall designs can be implemented. The application of an air and vapor barrier is one of the most common moisture control strategies. In this paper, the impact of vapor permeance of an air and vapor barriers on the hygrothermal performance of an ICF wall in three different cold and wet climates is examined using a validated Heat-Air-Moisture transfer model. The hygrothermal performance of an ICF wall assembly with different types of barriers and locations in the wall system for several wall designs is investigated. Results indicate that a smaller thickness of insulation on the outside facilitates removing the moisture towards the outside and installing low permeance air/vapor barrier systems on the outside prohibits drying and drives the moisture to the inside. Our findings also show that with the proper selection of insulation thickness and vapor control strategy moisture-related problems can be avoided.

scholarly journals Mitigating the Impact of Cellulose Particles on the Performance of Biopolyester-Based Composites by Gas-Phase Esterification

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 200 ◽  
Author(s):  
Grégoire David ◽  
Nathalie Gontard ◽  
Hélène Angellier-Coussy
Keyword(s):  
Gas Phase ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Stress And Strain ◽  
Moisture Sensitivity ◽  
Natural Systems ◽  
Palmitoyl Chloride ◽  
Diffusion Parameters ◽  
Dispersion State ◽  
The Impact

Materials that are both biodegradable and bio-sourced are becoming serious candidates for substituting traditional petro-sourced plastics that accumulate in natural systems. New biocomposites have been produced by melt extrusion, using bacterial polyester (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) as a matrix and cellulose particles as fillers. In this study, gas-phase esterified cellulose particles, with palmitoyl chloride, were used to improve filler-matrix compatibility and reduce moisture sensitivity. Structural analysis demonstrated that intrinsic properties of the polymer matrix (crystallinity, and molecular weight) were not more significantly affected by the incorporation of cellulose, either virgin or grafted. Only a little decrease in matrix thermal stability was noticed, this being limited by cellulose grafting. Gas-phase esterification of cellulose improved the filler’s dispersion state and filler/matrix interfacial adhesion, as shown by SEM cross-section observations, and limiting the degradation of tensile properties (stress and strain at break). Water vapor permeability, moisture, and liquid water uptake of biocomposites were increased compared to the neat matrix. The increase in thermodynamic parameters was limited in the case of grafted cellulose, principally ascribed to their increased hydrophobicity. However, no significant effect of grafting was noticed regarding diffusion parameters.

scholarly journals The Role of Structure and Interactions in Thermoplastic Starch–Nanocellulose Composites

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3186
Author(s):  
Emília Csiszár ◽  
Dávid Kun ◽  
Erika Fekete
Keyword(s):  
Composite Films ◽  
Water Vapor Permeability ◽  
High Water ◽  
Thermoplastic Starch ◽  
Vapor Permeability ◽  
Visible Spectroscopy ◽  
Different Types ◽  
Additional Water ◽  
Human Eyes

Composite films were fabricated by using cellulose nanocrystals (CNCs) as reinforcement up to 50 wt% in thermoplastic starch (TPS). Structure and interactions were modified by using different types (glycerol and sorbitol) and different amounts (30 and 40%) of plasticizers. The structure of the composites was characterized by visible spectroscopy, Haze index measurements, and scanning electron microscopy. Tensile properties were determined by tensile testing, and the effect of CNC content on vapor permeability was investigated. Although all composite films are transparent and can hardly be distinguished by human eyes, the addition of CNCs somewhat decreases the transmittance of the films. This can be related to the increased light scattering of the films, which is caused by the aggregation of nanocrystals, leading to the formation of micron-sized particles. Nevertheless, strength is enhanced by CNCs, mostly in the composite series prepared with 30% sorbitol. Additionally, the relatively high water vapor permeability of TPS is considerably decreased by the incorporation of at least 20 wt% CNCs. Reinforcement is determined mostly by the competitive interactions among starch, nanocellulose, and plasticizer molecules. The aging of the films is caused by the additional water uptake from the atmosphere and the retrogradation of starch.

scholarly journals Influence of Hydration State on Permeation Testing and Vapor Transport Properties of Protective Clothing Layers

2009 ◽  
Vol 4 (4) ◽  
pp. 155892500900400 ◽  
Author(s):  
Phillip W. Gibson ◽  
Heidi L. Schreuder-Gibson
Keyword(s):  
Water Vapor ◽  
Protective Clothing ◽  
Chemical Warfare Agents ◽  
Water Vapor Permeability ◽  
High Water ◽  
Chemical Warfare ◽  
Vapor Permeability ◽  
Liquid Form ◽  
Vapor Flux ◽  
Warfare Agents

Protective clothing systems composed of permselective polymer film laminates are an alternative to standard air-permeable garments based on activated carbon. These polymer layers are designed with high water vapor permeation rates and low permeation of chemical warfare agents. Polymer films that have a significant water vapor flux usually also have an affinity for water, and will hydrate and swell significantly at high humidity levels. The polymer film's increase in water content has the potential to affect the transport rate of chemical warfare agents in vapor and liquid form, and usually also has a large effect on the intrinsic water vapor permeability of the membrane.

scholarly journals Polybenzimidazole-based mixed membranes with exceptionally high water vapor permeability and selectivity

2017 ◽  
Vol 5 (41) ◽  
pp. 21807-21819 ◽  
Author(s):  
F. H. Akhtar ◽  
M. Kumar ◽  
L. F. Villalobos ◽  
H. Vovusha ◽  
R. Shevate ◽  
...  
Keyword(s):  
Water Vapor ◽  
Gas Separation ◽  
Water Vapor Permeability ◽  
High Water ◽  
Mixed Matrix Membranes ◽  
Vapor Permeability ◽  
Mixed Matrix ◽  
Matrix Membranes

Mixed matrix membranes containing polybenzimidazole and titania-based fillers with different morphologies are fabricated and tested for efficient water vapor/gas separation applications.

scholarly journals The Impact of the Mechanical Modification of Bacterial Cellulose Films on Selected Quality Parameters

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1275
Author(s):  
Izabela Betlej ◽  
Renata Salerno-Kochan ◽  
Agnieszka Jankowska ◽  
Krzysztof Krajewski ◽  
Jacek Wilkowski ◽  
...  
Keyword(s):  
Bacterial Cellulose ◽  
Water Vapor Permeability ◽  
Quality Parameters ◽  
Vapor Permeability ◽  
Physical Parameters ◽  
Significant Information ◽  
Cellulose Films ◽  
Native Cellulose ◽  
Modified Polymer ◽  
The Impact

This study investigated the effect of the homogenization of bacterial cellulose particles and their reintegration into a membrane on the mechanical and physical parameters of the films produced from them in relation to films made of native cellulose (not subjected to the homogenization process). Bacterial cellulose was obtained from a culture of microorganisms forming a conglomerate of bacteria and yeast, called SCOBY. The research has shown that the mechanical modification of bacterial cellulose contributes to an increase in the elongation of the material. Modified polymer films were characterized by a higher Young’s modulus and a much higher breaking force value compared to native cellulose. The mechanical modification of cellulose contributed to an increase in hygroscopicity and changes in water vapor permeability. The obtained results may provide significant information on the methods of modifying bacterial cellulose, depending on its various applications.

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