scholarly journals Impact of Water-Repellent Products on the Moisture Transport Properties and Mould Susceptibility of External Thermal Insulation Composite Systems

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 554
Author(s):  
Renata Roncon ◽  
Giovanni Borsoi ◽  
João L. Parracha ◽  
Inês Flores-Colen ◽  
Rosário Veiga ◽  
...  
Keyword(s):  
Water Vapor ◽  
Water Absorption ◽  
Transport Properties ◽  
Thermal Insulation ◽  
Moisture Transport ◽  
Laboratory Tests ◽  
Water Vapor Permeability ◽  
Water Repellent ◽  
Vapor Permeability ◽  
Composite Systems

External Thermal Insulation Composite Systems (ETICS) are constructive solutions widely used to increase the thermal insulation in new and retrofitted buildings. However, these systems can present several anomalies due to their constant exposure to weathering agents and anthropic factors. Water is generally the major cause of degradation. Thus, the application of water-repellent products can minimize the appearance of anomalies and increase the durability of the systems. In this paper, acrylic-based and siloxane-based hydrophobic products were applied to ETICS, with the aim of assessing the compatibility, effectiveness, and durability of these products. The moisture transport properties and mould susceptibility were assessed through laboratory tests on untreated and treated specimens. The durability of the hydrophobic treatments was also evaluated through artificial aging tests (heat-cold and freeze-thaw cycles). Results show that the protection products generally decreased water absorption, slightly decreased the drying rate, and presented adequate water vapor permeability. After aging, the products still had reasonable effectiveness and, with one exception, improved the water vapor diffusion of the systems. Additionally, ETICS underwent an alteration in the finishing coat (possible modification of the porosity) due to the aging cycles. No clear linear correlation was found between the contact angle values and water absorption results, evidencing the influence of other factors related to the composition of the water-repellent products.

scholarly journals Effect of Hygrothermal Aging on Hydrophobic Treatments Applied to Building Exterior Claddings

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 363 ◽  
Author(s):  
Giovanni Borsoi ◽  
Carlos Esteves ◽  
Inês Flores-Colen ◽  
Rosário Veiga
Keyword(s):  
Water Absorption ◽  
Transport Properties ◽  
Moisture Transport ◽  
Artificial Aging ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Minimal Impact ◽  
Hydrophobic Materials ◽  
The Aesthetic

Hydrophobic materials are among the most commonly used coatings for building exterior cladding. In fact, these products are easily applied to an existing surface, significantly reduce water absorption and have a minimal impact on the aesthetic properties. On the other hand, although these products have a proven effectiveness, their long-term durability to weathering has not yet been systematically studied and completely understood. For these reasons, this study aims to correlate the effect of artificial aging on the moisture transport properties of hydrophobic treatments when applied on building exterior claddings. Three hydrophobic products (an SiO2-TiO2 nanostructured dispersion; a silane/oligomeric siloxane; and a siloxane) were applied on samples of limestone and of a cement-based mortar. The moisture transport properties (water absorption, drying, water vapor permeability) of untreated and treated specimens were characterized. Furthermore, the long-term durability of the specimens was evaluated by artificial aging, that is, hygrothermal cycles (freeze–thaw and hot–cold). All treatments have significant hydrophobic effectiveness and improve the long term-durability of the treated specimens. However, the results showed that the three hydrophobic products have different effectiveness and durability, with the SiO2-TiO2 nanostructured dispersion being the most durable treatment on limestone, and the siloxane the most suitable for cementitious mortar.

scholarly journals Moisture and Thermal Transport Properties of Different Polyester Warp-Knitted Spacer Fabric for Protective Application

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Qing Chen ◽  
Dahua Shou ◽  
Rong Zheng ◽  
Ka-Po Maggie Tang ◽  
Bailu Fu ◽  
...  
Keyword(s):  
Water Vapor ◽  
Water Absorption ◽  
Thermal Insulation ◽  
Water Vapor Permeability ◽  
Volume Density ◽  
Air Permeability ◽  
High Mass ◽  
Vapor Permeability ◽  
Spacer Fabric ◽  
Spacer Fabrics

AbstractWarp-knitted spacer fabrics are generally used for sportswear, functional clothing, protective clothing, and other applications. This article studied the heat and mass transfer properties of polyester warp-knitted spacer fabrics from low thickness (2 mm) to high thickness (20 mm), from low mass (247.34 g/m2) to high mass (1,585.9 g/m2), and surface structure in plain or mesh construction. Water vapor permeability, air permeability, water absorption, and thermal insulation property were conducted to evaluate the spacer fabrics. The results revealed that with increasing volume density the water vapor permeability of spacer fabrics decreased, but the water absorption ratio increased. The water vapor permeability of fabrics increased when thickness decreased and volume density increased. It was further found that spacer fabrics with mesh worn nearby the skin and plain structure worn far from the skin could facilitate water vapor and air transmission. The difference of 8.82% for water vapor permeability and 14.19% for air permeability were found between testing mesh side up and down for the spacers (2.56 and 3.37 mm), respectively. Thermal insulation ratio was highly and significantly correlated with heat transfer coefficient at −0.958 and with thickness at 0.917. Thermal insulation ratio is highly and significantly correlated with air permeability at 0.941.

Process development of water-based polyurethane with acrylate terminal group under water vapor permeability and water repellency for nylon fabric

2020 ◽  
pp. 004051752094818
Author(s):  
Chung-Feng Jeffrey Kuo ◽  
Jiong-Bo Chen ◽  
Chi-Ping Yang ◽  
Min-Yan Dong
Keyword(s):  
Water Vapor ◽  
Water Vapor Permeability ◽  
Water Repellency ◽  
Terminal Group ◽  
Water Repellent ◽  
Vapor Permeability ◽  
Toxic Chemical ◽  
Nylon Fabric ◽  
Water Based ◽  
End Capping

This study synthesized water-based polyurethane with acrylate terminal group (WPUA) using the long carbon chain of stearyl acrylate to synthesize hydrophobic poly-stearyl acrylate (PSA). The proposed process could minimize environmental pollution caused by fluorine-containing monomers. As a water-based polyurethane (WPU) end-capping agent, the hydrophobic PSA and the hydrophilic and water vapor permeable WPU are copolymerized to form a WPUA functional resin with simultaneous water vapor permeability (WVP) and water repellency. Here, 2-mercaptoethanol was used to control the molecular weight of PSA to prepare the acrylate end-capping agent. PSA was then employed in WPU to form WPUA, which is characterized by the moisture permeability of WPU and water repellency of acrylic resin simultaneously. During the WPUA process, dimethylacetamide was used as a neutralizer to replace the traditional toxic chemical control drug triethylamine. This study set up the material and chemical structure to replace the toxic chemical-controlled drugs and organofluoride in the traditional preparation of moisture permeable and water repellent materials. The proposed process was proven to reduce the consumption of organic solvent, achieve WPUA copolymer stability, and provided moisture permeable and water repellent functions. In addition, Fourier transform infrared spectroscopy was used to determine the structure of WPUA, while thermogravimetry analysis and differential scanning calorimetry were performed to establish the thermal properties of WPUA. After the WPUA was padded on nylon fabric, its water drop contact angle was observed through a scanning electron microscope. The results showed that the contact angle of nylon fabric increased significantly, water repellency was reached, and WVP rises by 23.75%.

scholarly journals Study of TiO2-Modified Sol Coating Material in the Protection of Stone-Built Cultural Heritage

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 179
Author(s):  
Hui Shu ◽  
Ming Yang ◽  
Qiang Liu ◽  
Maobin Luo
Keyword(s):  
Water Vapor ◽  
Cultural Heritage ◽  
Water Absorption ◽  
Water Vapor Permeability ◽  
Acid Resistance ◽  
Coating Material ◽  
Vapor Permeability ◽  
Protective Effects ◽  
Coating Materials ◽  
Weather Resistance

Coating materials can effectively protect stone-built cultural heritage and, as such, research into coating materials has gained comprehensive attention from researchers. The aim of this work is to prepare a TiO2-modified sol coating material (TSCM) and study its protective effects on stone-built cultural heritage. TSCM and pure TiO2 sol (p-sol, unmodified; for comparison) were applied evenly over the entire surface of stone samples. The prepared stone samples included untreated stone, stone treated with pure sol, and stone treated with TSCM. The protective effects of TSCM were evaluated by water absorption, water vapor permeability, acid resistance, and weather resistance experiments. The results show that stone treated with TSCM has excellent water absorption and water vapor permeability, strong acid resistance, and good weather resistance, compared with untreated stone or stone treated with p-sol. The acid resistance of stone treated by TSCM was 1.75 times higher than that treated with traditional coating materials. The weather resistance cycle number of stone treated by TSCM was four times higher than that treated with organic protective materials. These findings are expected to provide useful suggestions for the protection of stone-built cultural heritage.

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.

Sign in / Sign up

Export Citation Format

Share Document