scholarly journals Hydrogen Sensing Performance of ZnO Schottky Diodes in Humid Ambient Conditions with PMMA Membrane Layer

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 835 ◽  
Author(s):  
Soohwan Jang ◽  
Sunwoo Jung ◽  
Kwang Hyeon Baik
Keyword(s):  
Water Vapor ◽  
Schottky Diodes ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Hydroxyl Groups ◽  
Ambient Conditions ◽  
Pmma Layer ◽  
Membrane Layer ◽  
Hydrogen Sensing ◽  
Sensing Performance

Enhanced hydrogen sensing performance of Pt Schottky diodes on ZnO single crystal wafers in humid ambient conditions is reported using a polymethylmethacrylate (PMMA) membrane layer. ZnO diode sensors showed little change in forward current when switching to wet ambient H2 conditions with 100% relative humidity. This sensitivity drop in the presence of water vapor can be attributed to surface coverage of hydroxyl groups on the Pt surface in humid ambient conditions. The hydrogen sensitivity of PMMA-coated diode sensors recovered up to 805% in wet H2 ambient conditions at room temperature. The PMMA layer can selectively filter water vapor and allow H2 molecules to pass through the membrane layer. It is clear that the PMMA layer can effectively serve as a moisture barrier because of low water vapor permeability and its hydrophobicity. In both dry and wet conditions, ZnO diodes exhibited relatively fast and stable on/off switching in each cycle with good repeatability.

scholarly journals DEVELOPMENT OF A BIODEGRADABLE COMPOSITE FILM FROM CHITOSAN, AGAR AND GLYCEROL BASED ON OPTIMIZATION PROCESS BY RESPONSE SURFACE METHODOLOGY

2021 ◽  
Vol 55 (7-8) ◽  
pp. 849-865
Author(s):  
PARTHIBAN FATHIRAJA ◽  
SUGUMAR GOPALRAJAN ◽  
MASILAN KARUNANITHI ◽  
MURALIDHARAN NAGARAJAN ◽  
MOHAN CHITRADURGA OBAIAH ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Response Surface Methodology ◽  
Water Vapor ◽  
Composite Film ◽  
Response Surface ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Hydroxyl Groups ◽  
Elongation At Break ◽  
Puncture Resistance

The aim of the study has been to develop a biodegradable film from marine polysaccharides. The optimization of polysaccharides quantity for the composite film was sought by empirical response surface methodology. The Box–Behnken Model Design was applied to optimize the concentration of chitosan (1.0-2.0% (w/v), agar (1.0-2.0% (w/v) and glycerol (0.1-0.5% (w/v) as independent variables to achieve the goal. The overall desirability function fits with the quadratic model (0.862043) at a significant level (p < 0.05) for the optimum concentration of chitosan (1.5% (w/v), agar (2.0% (w/v) and glycerol (0.41% (w/v) to obtain the minimum water vapor permeability (7.25 10-10g m m-2 Pa-1 s-1) and maximum tensile strength (12.21 Ma P), elongation at break (7.32%) and puncture resistance (16.18 N) in the optimized composite film. The absolute residual errors of experimental and predicted responses were between 1.24 and 3.56% acceptable levels. Attenuated total reflection–Fourier transform infrared spectroscopy confirmed the intermolecular non-covalent hydrogen bond between the hydroxyl groups of agar and glycerol with the amino group of chitosan. 3D atomic force microscopy images revealed that the chitosan, agar and glycerol film has layer-by-layer smooth surface properties due to homogenous interaction among the polysaccharides; this provides the film with good mechanical properties and with functional application. Chitosan was found to be responsible for the lower level of water vapor permeability and higher puncture resistance of the film. Tensile strength and elongation at break were influenced by agar and glycerol. The whiteness of the film was negatively affected with the concentration of chitosan.

Rice straw paper sheets reinforced with bleached or unbleached nanofibers

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohammad L. Hassan ◽  
Wafaa S. Abou-Elseoud ◽  
Amaal H. Abd Elkader ◽  
Enas A. Hassan
Keyword(s):  
Mechanical Properties ◽  
Water Vapor ◽  
Rice Straw ◽  
Lower Cost ◽  
Cellulose Nanofibers ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Hydroxyl Groups ◽  
Paper Sheet ◽  
Tearing Resistance

Abstract Cellulose nanofibers isolated from unbleached pulp are characterized by different surface properties due to presence of lignin at their surface, in addition to lower cost than isolated from bleached pulp. In the current work, the effect of cellulose nanofibers isolated from unbleached neutral sulfite and bleached soda rice straw pulps (so called UBCNF and BCNF) on improving paper sheet properties of unbleached and bleached rice straw pulp (so called UBP and BP) was studied. The effect on mechanical properties (tensile strength, burst strength, and tearing resistance) and physical properties (porosity and water vapor permeability) was studied. Scanning electron microscopy (SEM) was used to assist in explaining the obtained results. The result showed that using BCNF and BP resulted in better improvement in mechanical properties and also more effective in reducing porosity of paper sheets than in case of using UBCNF and UBP. These results indicated stronger bonding between nanofibers and pulps’ fibers in case of using BCNF and BP (surfaces rich in cellulose hydroxyl groups) than in case of UBCNF and UBP (surfaces rich in lignin). Water vapor permeability of paper sheets made from unbleached or bleached pulps did not significantly affect by the addition the nanofibers.

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.

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

2020 ◽  
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.

Water-vapor permeability control of PDMS by the dispersion of collagen powder

2009 ◽  
Vol 4 (3) ◽  
pp. 442-449 ◽  
Author(s):  
Yuhua Zhang ◽  
Masatoshi Ishida ◽  
Yutaka Kazoe ◽  
Yohei Sato ◽  
Norihisa Miki
Keyword(s):  
Water Vapor ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Collagen Powder

scholarly journals Incorporation of bentonite clay in cassava starch films for the reduction of water vapor permeability

2018 ◽  
Vol 105 ◽  
pp. 637-644 ◽  
Author(s):  
M.K.S. Monteiro ◽  
V.R.L. Oliveira ◽  
F.K.G. Santos ◽  
E.L. Barros Neto ◽  
R.H.L. Leite ◽  
...  
Keyword(s):  
Water Vapor ◽  
Water Vapor Permeability ◽  
Bentonite Clay ◽  
Cassava Starch ◽  
Vapor Permeability ◽  
Starch Films
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