SORPTION KINETICS MODEL APPLICATION ON THE MEASUREMENT OF WATER VAPOR PERMEABILITY IN BUILDING MATERIALS

The article is devoted to the analysis of sorption kinetics, permeability, and diffusion of water vapor in porous polymeric membranes of different hydrophilicities and through-porosities. The water transport measurement with a constant gradient of partial pressure allows the authors to obtain reliable characteristics for porous membranes, films, artificial leathers, and fabrics of various chemical natures (synthetic and bio-based) and phase structures. All the kinetic permeability curves were determined and effective diffusion coefficients, as well as their apparent activation energies, were calculated at the stationary and non-stationary stages of the mass transfer. The relationship between the sorption–diffusion characteristics of the polymer barriers and their vapor permeability is traced. Within the framework of a Zolotarev–Dubinin dual dispersive model, an analytical equation is obtained that relates permeability to diffusion coefficients of water vapor in the pore volume, polymer skeleton material using such characteristics as porosity and the solubility coefficient. It is proposed to use this equation to predict the sorption properties for barrier and porous materials of complex architecture specifically in food packaging.

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

E3S Web of Conferences ◽

10.1051/e3sconf/202017214003 ◽

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.

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

Journal of Polymer Engineering ◽

10.1515/polyeng-2020-0071 ◽

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.

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

Coatings ◽

10.3390/coatings11050602 ◽

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.

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

Molecules ◽

10.3390/molecules26113090 ◽

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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Reduction of Water Vapor Permeability in Food Multilayer Biopackaging by Epitaxial Crystallization of Beeswax

Food and Bioprocess Technology ◽

10.1007/s11947-021-02628-9 ◽

2021 ◽

Author(s):

Florencia Cruces ◽

María Guadalupe García ◽

Nelio Ariel Ochoa

Keyword(s):

Water Vapor ◽

Water Vapor Permeability ◽

Vapor Permeability ◽

Epitaxial Crystallization

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Upcycling of Vine Shoots: Production of Fillers for PHBV-Based Biocomposite Applications

Journal of Polymers and the Environment ◽

10.1007/s10924-020-01884-8 ◽

2020 ◽

Cited By ~ 1

Author(s):

Grégoire David ◽

Laurent Heux ◽

Stéphanie Pradeau ◽

Nathalie Gontard ◽

Hélène Angellier-Coussy

Keyword(s):

Water Vapor ◽

Gas Phase ◽

Mechanical Performance ◽

Low Cost ◽

Water Vapor Permeability ◽

Contact Angles ◽

Vapor Permeability ◽

Water Contact ◽

Median Diameter ◽

Cost Of Materials

Abstract This paper aims at investigating the potential of vine shoots (ViSh) upcycling as fillers in novel poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHBV) based biocomposites. ViSh particles of around 50 µm (apparent median diameter) were obtained combining dry grinding processes, and mixed with PHBV using melt extrusion. Thermal stability and elongation at break of biocomposites were reduced with increasing contents of ViSh particles (10, 20 and 30 wt%), while Young’s modulus and water vapor permeability were increased. It was shown that a surface gas-phase esterification allowed to significantly increase the hydrophobicity of ViSh particles (increase of water contact angles from 59° to 114°), leading to a reduction of 27% in the water vapor permeability of the biocomposite filled with 30 wt% of ViSh. The overall mechanical performance was not impacted by gas-phase esterification, demonstrating that the interfacial adhesion between the virgin ViSh particles and the PHBV matrix was already good and that such filler surface treatment was not required in that case. It was concluded that ViSh particles can be interestingly used as low cost fillers in PHBV-based biocomposites to decrease the overall cost of materials.

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