Water Vapor Resistance Research Articles

Water vapour permeability of inorganic construction materials

Water vapour permeability (WVP) data on brick, stone, plaster and cement-based materials from some seventy publications are reviewed and assessed. Almost all sources use standard cup-test methods or close variants. Comparisons of WVP values from different sources on similar materials confirm that reproducibility between different laboratories is poor. Some deficiencies of cup-test methods are discussed, including uncertainties arising from the use of saturated-salt humidistats and desiccants. There is evidence that the water vapour resistance factor decreases as volume-fraction porosity increases, and data support a simple porosity–tortuosity relation. Data also show that the resistance factor decreases with increasing mean relative humidity across the test specimen, with the wet-cup value consistently lower than the dry-cup values for a given material. The contribution of liquid film flow to mass transfer is discussed. It is shown how film thickness and film-flow permeability may be estimated from the water-vapour sorption isotherm; and a related regression equation is developed It is concluded that available data are inadequate to establish the fundamental physics of WVP; vapour-only permeability data for engineering purposes should be obtained in dry-cup tests at low humidity; and research studies should aim to integrate the WVP into the framework of unsaturated flow theory.

A new high entropy rare earth disilicate ceramic (Lu1/8Yb1/8Sc1/8Er1/8Y1/8Ho1/8Dy1/8Tb1/8)2Si2O7: High temperature corrosion of water vapor and molten calcium–magnesium–aluminosilicate (CMAS)

A new β-(Lu1/8Yb1/8Sc1/8Er1/8Y1/8Ho1/8Dy1/8Tb1/8)2Si2O7 ((8RE1/8)2Si2O7) disilicate was prepared using a solid reaction process to protect SiCf/SiC CMC component materials. The thermal properties and corrosion resistance of (8RE1/8)2Si2O7 were systematically studied. Experimental results showed that (8RE1/8)2Si2O7 exhibited lower thermal conductivity than that of one-component silicate materials, only 1.80 (W•m−1•K−1) at 1000 °C. Meanwhile, (8RE1/8)2Si2O7 also exhibited superior water vapor and CMAS corrosion resistance. The weight loss was 1.05 × 10−4 g/cm2 after 200 h corrosion at 1400 °C. When it interacted with CMAS at 1300 ℃ for 48 h, the reaction layer was only 16 µm. Therefore, (8RE1/8)2Si2O7 could be regarded as a remarkable candidate for T/EBC.

Development of multifunctional sustainable packaging from acetylated cellulose micro-nanofibrils (CMNF)

Cellulose micro-nanofibrils (CMNF) with different fibrillation levels were partially acetylated while preserving their morphological and native crystalline structure. The morphological changes due to fibrillation and chemical modification were observed using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and optical profilometry. The change in tensile and burst strength, barrier, and biodegradability profile were investigated which revealed that the mechanical properties of the unmodified CMNF films increased with increase in extent of fibrillation. However, the mechanical strength of the acetylated film decreased with the increase in degree of acetylation. The stretching or folding property of the film increased with the increase in both the fibrillation and acetylation. The contact angle value increased due to a higher degree of fibrillation and acetylation because they increased the hydrophobicity and consequently enhanced the air and water vapor resistance of the unmodified and modified CNF films. Furthermore, all films exhibited the highest resistance against oil and grease, and the biodegradability test substantiated that CNF films were compostable in soil. In total, this work expresses new pathways to enhance the barrier properties of biodegradable CNF films by regulating the degree of fibrillation and acetylation, thus can emerge as sustainable alternatives for packaging and agriculture applications.

Effect of calendering on the performance of 100% recycled polyester weft-knitted fabrics

Government policies focus on the textile sector to follow a tendency towards sustainability and circular economy, thus, raising the use of recycled textiles which require further performance improvement to be completely competitive with other textile products while using secondary treatments that are also environmentally friendly. In this study, a 100% recycled polyester weft-knitted fabric, currently used by commercial brands in the apparel and sport textile industry, is calendered and its properties are examined before and after such treatment. This research investigates variations in the physical (appearance and thickness), mechanical (tensile strength and elastic recovery), and physiological (water vapour resistance, spray test, and wettability) characteristics of the samples. The calendering treatment reduces water vapour resistance up to 23%, which is particularly interesting for garments used in sports. Additionally, the contact angle is increased by the calendering process which translates in poorer wettability. Novel findings of this work include that, whereas in the original fabric sweat marks are visible, sweat stains do not appear on the calendered fabric and moisture management improves, while mechanical properties do not undergo significant changes. These results have not been previosly found in the literature, giving a particular interest to a conventional process in this type of recycled fiber that can contribute to the advancement of knowledge in the textile industry and enhance the performance of treated fabrics. All these aspects make the treatment particularly interesting to improve the technical performance of the textile material while using an economic treatment with low effect on the environment.

Evaluation of the comfort properties of functional knitted fabrics for people with special needs

In this study, several comfort properties of knitted fabrics were investigated. Seven types of knitted fabrics made of combinations of natural fibres (e.g., cotton, wool, and bamboo), artificial fibres (e.g., modal) and synthetic fibres (e.g., polyester and acrylic) were produced. The knitted samples were subjected to several comfort tests, including air permeability, thermal resistance and water vapour resistance assessments. To determine the correlations among the comfort properties of the fabric, fabric structural properties, such as fabric weight and fabric thickness, were considered. Moreover, statistically significant differences were found in terms of dry thermal resistance, water vapour resistance and air permeability depending on the structural parameters of the fabric.

Water vapour resistance modelling of basic weaving structure

Water vapour diffusion through textile fabrics plays a crucial role in maintaining body comfort. Developing and producing comfortable textiles is a major challenge for manufacturers of fibres, yarns and fabrics. This study aims to develop a simple model to predict the water vapour permeability of textile fabrics as a function of their structural parameters to assist manufacturers in developing comfortable fabrics. To achieve this goal, geometric modeling of the woven structure was proposed to calculate porosity at the micro-and macro-pores level. Two mathematical models were introduced based on the principle of diffusion of water vapour through a textile fabric. To validate the two models, a series of 18 samples was prepared with three basic fabric structures: Plain, Twill and Turc Sateen. To vary the compactness of the structures, three weft densities were chosen: 18, 21 and 24 picks/cm. In addition, since the material influences water vapour diffusion, two types of weft yarns were inserted: 50% CO/50% PET and 100% PET. The results show that the two models are reliable for predicting water vapour resistance (Ret) depending on the structural parameters of the textile fabric.

Study on the Comfort Properties of Knitted Fabrics Produced from Conventional and Sustainable Cotton and Polyester Fibres

Recently, the production of organic fibres and the recycling of textile waste have become essential global issues due to the decrease in non-renewable resources and the increase in disposal costs. The aim of this work was to identify changes in the properties of single jersey knitwear produced from conventional and sustainable fibres after 20 washes. The samples were knitted from different conventional and sustainable yarns. The selected conventional fibres were 100% cotton, 50% cotton-50% polyester and 100% polyester, while the sustainable fibres were 100% better cotton, 100% recycled polyester, and 50% organic cotton-50% recycled polyester. Measurements were taken before and after 20 washes according to the relevant standards. It was found that fabric produced from 100% recycled polyester is suitable for active sportswear due to its high air permeability, and resistance to heat and water vapor. In addition, the fabric with 50% organic cotton-50% recycled polyester fibres was more suitable for cold environmental conditions due to its lowest water vapor resistance, good air permeability and high thermal resistance.

Efficient Fresh Lamp Light-Harvesting Films with the Self-Activating Continuous and Recyclable Bactericidal Ability for Ultrapersistent Freshness of Perishable Muscle Food.

A large quantity of perishable muscle food is being wasted due to harmful bacteria infestation during the sales and circulation each year and facing challenges. In this study, a self-activated bactericidal active film (PLA/g-C3N4@PCN-224) responsive to fresh lamp light was prepared, which showed excellent hydrophobicity, water vapor resistance, and thermal stability. Due to the synergistic effect between light-induced reactive oxygen species and the high specific surface area of g-C3N4@PCN-224, this film still maintains 99.99% bactericidal efficacy against Escherichia coli and Staphylococcus aureus after 10 days of continuous bactericidal activity test. The results of cell and hemolysis experiments indicated that the film was safe and nontoxic and can effectively preserve fresh pork for 7 days. Moreover, the film also exhibited a recyclable and efficient killing activity. A strategy for achieving ultrapersistent freshness of perishable muscle food was provided.

From waste to eco-friendly biofilms: Harnessing cottonseed hull proanthocyanidins for sustainable solutions

A circular sustainable bioeconomy model, utilizing renewable resources like agricultural waste biomass, can address environmental issues caused by the massive utilization of fossil resources. The study aims at exploring the potential utilization of underutilized cottonseed hulls (CSHs) as a source of bioactive proanthocyanidins (PAs), and investigate their applicability in the production of biodegradable films. FT-IR, HPLC-QTOF/MS, MALDI-TOF/MS analyses served for characterizing the structure of PAs extracted from CSHs, and thiolysis reaction revealed that they primarily consisted of (epi)catechins with a few (epi)gallocatechins and (epi)afzelechin units, forming oligomeric proanthocyanidins of which the mean degree of polymerization (mDP) was 2.99. Three monomers, ten dimers, one tetramer, one pentamer, and one hexamer were theoretically identified in CSHs for the first time. The unique structure of CSHs sets them apart from most plants. The extracts displayed high in vitro antioxidant activity with IC50 value of 0.074 in DPPH assay and 0.018 mg/mL in ABTS assay. Additionally, the CSH extracts were incorporated as antioxidants into chitosan (CS)-based biodegradable films. The addition of 0.25% CSH extracts significantly improved film thickness and water vapor resistance, and also reduced the water solubility and visible light transmission. Furthermore, the films enhanced the blueberry quality and extended the shelf-life. This comprehensive study not only addresses waste management issues but also offers avenues for innovative applications in sustainable agriculture and packaging.

Extended hygrothermal characterization of unstabilized rammed earth for modern construction

Although hygrothermal properties of rammed earth represent great potential for improving thermal comfort during hot summers, still little knowledge is available about this topic. The literature lacks complete sets of hygrothermal characteristics of rammed earth, although they are fundamental for heat and moisture transfer modeling necessary to predict earthen building performances. The present work reports the results of a large collaboration between four academic laboratories in order to obtain an extended hygrothermal characterization of rammed earth, focusing on the material used in a modern construction in Lyon, France. The aim of the article is to provide for the same kind of soil an extend characterization on a large span of relative humidity to provide complete set of material properties for heat and moisture transfer simulation. The hygrothermal measurements cover adsorption and desorption isotherm, intermediate isotherm loop, specific heat capacity, dry thermal conductivity, moisture-dependent thermal conductivity and water vapor resistance factor for a large span of relative humidity. In addition, the capillary rise test was performed to estimate the liquid transport coefficient for suction and redistribution. The results show that variations in the density of the samples have a low impact on sorption isotherm, while they have a non-negligible impact on thermal conductivity and water vapor permeability. Surprisingly, variations in the grain size distribution do not produce a significant modification in the sorption isotherm, while hysteresis slightly reduces when bigger grains are added to the soil composition. Approximation of empirical model coefficients for the determination of moisture-dependent thermal conductivity is proposed for rammed earth materials.

Evaluation of the performance properties of modacrylic-cotton blended underwear fabrics manufactured for firefighters

In this study, the mechanical, comfort and flame-retardant properties of different knitted fabric structures containing modacrylic fibers with different blend ratios were investigated. Single jersey, rib, pique, three-thread fleece and interlock fabrics were produced with modacrylic/cotton blended yarns and evaluated comparatively. In order to understand the effect of antistatic fiber content on the investigated properties, two fabrics with antistatic fiber were produced. Since modacrylic fibers have moderate abrasion resistance, pilling resistances of the fabrics are not excellent. Due to the knitted fabrics having a soft and flexible structure, their fabric stiffness and bursting strength are quite high. It has been determined that water vapor resistances of all fabrics are satisfactory and the moisture management properties of the S1 (60% modacrylic, 40% cotton) and R1 (60% modacrylic, 40% cotton) fabrics are excellent. All the fabrics passed the flame-retardancy tests and it is sufficient that the modacrylic ratio is between 50% and 60% according to the fabric structure. Results also showed that 2% antistatic fiber content had no effect on the mechanical, thermal comfort and flame-retardancy properties. Since the air permeability, water vapor resistance and moisture management properties of S1 and R1 specimens are good enough, it is recommended to use one of them according to different temperature conditions. Evaluation of modacrylic fiber blended fabrics in different knitting types in terms of mechanical strength, thermal comfort and flame resistance properties together constitutes the originality of the work. Thus, it was possible to evaluate the effect of different knitting types and contents on all tests.

Low-temperature sintering of multifunctional SiC catalytic membrane for synergistic emission control of toluene and dust

SiC catalytic membranes have shown great potential in dust and atmospheric pollutant emission control. However, their high sintering temperature (up to 1850 °C) and the ‘trade-off’ effect between its gas permeance and catalytic performance have hindered their widespread application. In this study, a high-performance CuO-loaded SiC catalytic membrane was fabricated to address the above issues using a liquid phase sintering and surficial reconstruction (LSSR) strategy. The low melting point of CuO enables the liquid phase sintering of CuO-SiC membrane at a significantly reduced temperature of 1040 °C, and the formation of CuO nanoparticles (CuO-NPs) on bulk CuO in CuO-SiC membrane (CuO-NPs/CuO-SiC) is achieved through a surficial reconstruction process. The resulting CuO-NPs/CuO-SiC catalytic membrane exhibits a high gas permeance of 275.8 m3·m−2·h−1·kPa−1 and a bending strength of 14.2 MPa. The CuO-NPs/CuO-SiC catalytic membrane also displays complete (100 %) toluene oxidation and PM2.5 filtration efficiencies at 280 °C, as well as enhanced water vapor resistance and long-term stability. The LSSR was successfully applied to fabricate an CuO-NPs/CuO-Al2O3 catalytic membrane, which shows complete toluene oxidation and PM2.5 filtration efficiency at 300 °C, demonstrating that LSSR is readily extended to fabricating other ceramic and metal-ceramic-based catalytic membranes.

Crosslinked fish scale gelatin/alginate dialdehyde functional films incorporated with carbon dots derived from pomelo peel waste for active food packaging

A multifunctional and environmentally friendly composite film was developed by incorporating pomelo peel-derived carbon dots (PCDs) into a fish scale gelatin (FSG)/alginate dialdehyde (ADA) biopolymer matrix. ADA was used to reinforce the physicomechanical properties of the FSG film via Schiff base crosslinking. PCDs with strong antioxidant and antimicrobial activities were synthesized via a hydrothermal method. The effect of various PCDs content on the surface morphological, physicochemical, and functional characteristics of the composite films was investigated. The results showed that the introduction of PCDs into the FSG/ADA matrix effectively reinforced the mechanical performance, enhanced the water vapor and water resistance, increased UV-light blocking, conferred fluorescence properties, and improved the thermal properties of the composite films. Under 3 wt% PCDs content, the FSG/ADA/PCDs-3 % composite film not only presented significant antioxidant capacity with a radical scavenging rate of 91.71 % for DPPH and approximately 100 % for ABTS, but also exhibited excellent antimicrobial ability against bacteria and fungi. Results of a preservation experiment showed that the prepared FSG/ADA/PCDs-3 % film preserved the physiological qualities of strawberries post-harvest and extended their shelf-life to 7 days at room temperature. Overall, the fabricated FSG/ADA/PCDs composite films are promising for use in eco-friendly active food packaging.

Effects of Stearic Acid and Zein Incorporation on Refined Kappa Carrageenan-Based Composite Edible Film Properties

Incorporating hydrophobic materials into a polysaccharide-based film to form a composite edible film has been considered an effective way to strengthen the film properties, especially the water vapor resistance. Fatty acids, such as stearic acid, with long-chain and straight structures, exhibit strong hydrophobic performance to prevent water vapor diffusion through the film surface. Meanwhile, zein has been revealed as an encouraging material due to its compactness, less allergic, and gas barrier properties. The investigation of kappa-carrageenan/zein/stearic acid-based green composite edible film has been limited. Thus, this study aims to examine the effect of increasing stearic acid and zein concentrations on improving the moisture barrier and mechanical properties of kappa carrageenan-based composite edible film. Different concentrations of stearic acid (5, 10, and 15% w/w carrageenan) and zein (2.5, 5, and 7.5% w/w carrageenan) were applied to the composite edible film prepared using the solution casting method. The fabricated films have a thickness of 0.092–0.122 mm. The results indicated that increasing the concentration of stearic acid enhances the water vapor barrier and tensile strength of the edible film (p < 0.05). However, the increased zein concentration slightly weakened the water vapor barrier properties. Then, the elongation of the manufactured films was quite improved by the increment of stearic acid proportion, but neither by the increment of zein proportion nor the combination of these two substances. However, the incorporation of stearic acid and zein into refined-kappa carrageenan-based film remarkably improved the tensile strength, elongation, and water vapor barrier properties by 12–18%, 23–27%, and 43–44%, respectively, in comparison to the neat film. Based on the analysis result, the manufactured film which consists of 10% stearic acid and 2.5% zein is considered as the best film formula. This study, therefore, revealed the potentiality of stearic acid enforcement in food packaging applications.

Water Vapour Resistance of Ceiling Paints—Implications for the Use of Smart Vapour Barriers in Compact Wooden Roofs

Smart vapour barriers enable building envelopes to dry toward the interior side. This property can be used in compact wooden roofs to create more slender structures by placing the wooden load-bearing elements inside the insulation layer. There is, however, some concern that the ceiling assembly on the interior side may inhibit inward drying by trapping moisture between the vapour barrier and the ceiling boards. This article examined the water vapour resistance of gypsum boards painted with two, four, and six layers of typical ceiling paints. WUFI® 2D simulations were conducted to assess the risk of mould growth in compact wooden roofs with painted board ceilings. It was found that a painted ceiling board may exhibit an equivalent stagnant air layer thickness (sd value) between 0.074 m for two layers of the most vapour-open paint and 0.53 m for six layers of the least vapour-open. For an unpainted board, the sd value was measured to be 0.071 m. The difference was not found to make a substantial impact on the drying of a typical compact wooden roof. The application of paint may cause the assembly to dry at a slightly slower rate but was not found to present a notably higher risk of mould growth, even under unfavourable conditions.

Evaluation of the moisture management and air permeability of cotton/antistatic polyester knitted fabrics

This research fills in the missing knowledge on the moisture management and air permeability of knitted fabrics developed using mixed cotton/antistatic polyester yarns with both antibacterial and antistatic behavior to enhance their functionality. The effect of the knit pattern, technical side, percentage of fiber mixture and treatment on water absorption capacity and time, relative water vapor permeability and resistance, and air permeability of developed fabrics was investigated. The 1x1 rib knit and half-Milano rib knit patterns were applied in each 4 percentages of cotton and antistatic polyester and 3 types of finishing to prepare 24 fabrics. The water absorption capacity for 1x1 rib knit fabrics was in the range of 182–231% and 162–237% for the half-Milano knitted fabric with the ∼20% increase when increasing the percentage of antistatic polyester or applying the treatment. The water absorption time depended on the pattern, the fabric treatment, and the percentage of the fiber mixture. The applied antibacterial treatment significantly prolonged the water absorption time of most of the dyed and softened samples. The 1x1 rib knitted fabrics showed significantly higher water vapor and air permeability than the half-Milano rib knitted fabrics. The relative water vapor and air permeability of the treated samples increased significantly with an increasing percentage of polyester. Research results are of great practical value when designing new textiles and simulating mathematically their comfort behavior when choosing them for a particular garment.

Investigations of Three‐Layer Systems Intended for Protective Clothing for Prematurely Born Babies

AbstractOne of the most significant problems occurring among premature babies is high transepidermal water loss and associated heat loss. To prevent this problem protective clothing for premature babies is developed which consists of a membrane that allows partial transmission of water vapor, combined with other textile materials. The purpose of this work is to characterize two pre‐selected three‐layer systems in terms of biophysical properties that fulfill their requirements for premature infants. Samples of materials are investigated to determine biophysical comfort (tests of thermal resistance, water vapor resistance and air permeability), mass per unit area and thickness. In order to visualize the structure and chemical composition of the tested materials, Scanning Electron Microscopy (SEM) were performed. The mechanical properties of the investigated materials and the evaluation of the total hand value were also characterized; the samples were tested on a Kawabata Evaluation System (KES) device. Protective garments designed for premature babies should be characterized by high thermal insulation and moisture barrier properties. In addition, it should have optimal air permeability properties and fairly low surface weight in order not to burden the baby's delicate skin.

Facile Method to Create PdCe–MnOx Catalyst for Decomposing O3 under Humidity Conditions

Manganese oxides are one of the most promising candidates for ambient decomposition of O3. However, catalysts with high efficiency require complicated preparation processes to cultivate active microstructures. This study developed a simple and easy to scale up method to produce catalysts via thermal annealing of Mn precursor. With slight addition of Ce and Pd, the obtained PdCe–MnOx catalyst exhibited excellent O3 removal activity in the presence of water vapor. Numerous characterization methods, including X-ray diffraction, high-resolution transmission electron microscopy, mapping, Brunauer–Emmett–Teller, H2-temperature-programmed reduction, O2-temperature-programmed desorption, X-ray photoelectron spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy, were applied to explore the relationship between activity and structure. The slight addition of Pd and Ce not only boosts the formation of surface vacancy species but also enhances the water vapor resistance, all of which contribute to its excellent ozone decomposition performance.

Research on monitoring the transfer of water vapors through textile materials using humidity sensors

The ability of textile materials to transfer water vapor greatly influences the protective and comfort functions of clothing. In order to appreciate the water vapor transfer capacity, standard methods have been defined, but these standardized methods have also some drawbacks. One of these drawbacks is the fact that the environmental conditions for determining the standard characteristics greatly differ from the real operating conditions, which are mostly dynamic. This paper proposes a method for dynamic monitoring of water vapor transfer through multilayer textile assemblies using relative humidity sensors. In addition, the method offers the possibility to determine the water vapor resistance of the textile materials with good accuracy and at a much lower price than using the standard ISO 11092 − 2014. These humidity sensors can be an important component of smart wearable electronic textiles and have potential applications in healthcare in the management of wounds, bed-wetting, and skin pathologies or for microclimate control in clothing for military, firemen, athletes, etc.

Earth-Based Building Incorporating Sargassum muticum Seaweed: Mechanical and Hygrothermal Performances

Once the tide recedes and leaves a significant amount of stranded seaweed on the coast, marine macroalgae pose a serious threat to the surrounding area. Through this work, we considered a large-scale application of stranded macroalgae in building construction. For the first time we studied the impact of incorporating Sargassum mitucum seaweed fiber in replacement of flax fiber used for a standard structural cob. Thus, cob specimens were elaborated and analyzed to evaluate their compressive and hygrothermal performances. It was found that the compressive strength and water vapor resistance factors of cob decreased with the algae content. Additionally, the obtained results showed that a cob made with Sargassum muticum algae presented better thermal (insulation and inertia) and hygroscopic properties than those of a cob made with a flax fiber. Indeed, the replacement of flax straw by algae lead to a reduction in the thermal conductivity by 38% when compared to the standard cob with 2.5% of flax straw fiber. Consequently, numerical simulation showed a reduction in the energy needs in buildings made with an algae-based cob when compared to those made with a flax-based cob. This study can contribute to a global environmental and economic issue, i.e., the valorization of brown algae on a large scale. Indeed, the worldwide knows the largest sea of sargassum algae extent measures over 8850 km2. This huge mass of brownish algae is expanding every year, which now covers an area from Africa to the Caribbean. It weighs more than 20 million tons and extends from the Gulf of Mexico to the west coast of Africa. We show that stranded algae, which are considered as wastes, have the ability to improve the mechanical and hygrothermal performance of cob-based material.