• Title, Summary, Keyword: Water vapor transmission

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Measurement of Water Vapor Permeability of Bio-polymer Films (생고분자 필름의 투습도 측정)

  • Rhim, Jong-Whan
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.5 no.1
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    • pp.37-46
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    • 1999
  • Water vapor permeability of films is commonly calculated from the water vapor transmission rate of the film measured using a permeability cup method which is essentially a gravimetric method. This method was originally developed for petroleum based plastic films with low water vapor permeability. In the case of hydrophilic bio-polymer films, the resistance caused by a stagnant air layer, which is developed between the underside of the film mounted on the cup and the surface of the desiccant saturated salt solution or distilled water, can be significant and, if neglected, ran lead to underestimation of water vapor transmission rates. Therefore, it is necessary to correct water vapor transmission rate data to accurately estimate the water vapor permeability of bio-polymer films.

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The Wearing Sensation of Men and Women in Sports Wear with Waterproof and Water Vapor Permeable Fabrics (성인 남녀의 투습방수소재 스포츠 웨어의 소재별 착용감에 관한 연구)

  • Cho, Ji-Hyun;Ryu, Duck-Hwan
    • Korean Journal of Human Ecology
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    • v.9 no.1
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    • pp.47-61
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    • 2000
  • The purpose of this study was to examine the performance and properties of sports wear that have the excellent wearing sensation and are in harmony with the functions of human bodies. With four kind(sample A, B, C, D) of materials which have different water vapor transmission, the physiological responses of human bodies and the changes of subjective sensations were studied through the actual aerobic sports program at $20^{\circ}C$, 60%R.H. The forehead temperature had the minimal variation among the local skin temperatures. The fabrics of low water vapor transmission demonstrated high breast temperature. There are significant differences among materials depending on the humidity in clothes(especially back and breast), which was about 6 % for breast and about 14 % for back. The order of loss in body weight was in the opposite direction to that of water vapor transmission for each material.

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Water-Vapor Transfer Characteristics of Carrageenan-Based Edible Film (카라기난 필름의 투습 특성)

  • Rhim, Jong-Whan;Hwang, Keum-Taek;Park, Hyun-Jin;Jung, Soon-Teck
    • Korean Journal of Food Science and Technology
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    • v.28 no.3
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    • pp.545-551
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    • 1996
  • Water-vapor transmission rate and water-vapor permeability of carrageenan-based edible film with three different thicknesses of 0.05, 0.08 and 0.11 mm were measured to investigate the potential applicability of the films to powder foods at five different temperatures (20, 25, 30. 35 and $4^{\circ}C$) and three different relative humidities (50. 70 and 90% RH). Water-vapor transmission rate of the carrageenan-based film was gound to be 2.3 times higher than that of polyethylene (PE) film and water-vapor permeability of the film was 45-230 times higher than that of PE film. Water-ydpor permeability of the film seemed to increase linearly with the film thicknees like other hydrophilic edible films. Water-vapor transmission rate were found to be dependent on the temperature. Activation energies of the water-vapor transmission rate of the film were found to be between 7.898 and 12.8702 kj/mol depending on the film thickness. The water-vapor transmission rate of the film showed the typical kinetic compensation effect between activation energies and preexponential factors. which was proved by the linear increase in the value of logarithms of preecponential factor.

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Environmentally Friendly Moisture-proof Paper with Superior Moisture Proof Property (I) -Properties of Moisture Proof Chemicals- (방습 효과가 우수한 환경친화적 방습지(제1보) -방습제의 특성-)

  • 유재국;조욱기;이명구
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.33 no.4
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    • pp.15-20
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    • 2001
  • The function of the moisture-proof paper is to prevent moisture from adsorbing into the packed goods. Water-vapor transmission rate of the moisture-proof paper should be less than 100g/$m^2$.24hr and the optimum rate would be less than 50g/$m^2$.24hr. In general the moisture-proof paper has been made by laminating polyethylene or polypropylene on top of the base paper. However this kind of moisture-proof paper has a problem in recycling so that it brings about environmental pollution. In general the moisture-proof paper has been made by laminating polyethylene or polypropylene on top of the base paper. However this kind of moisture-proof paper has a problem in recycling so that it brings about environmental pollution. The purpose of this paper was to make moisture-proof paper using the mixture of SB latex and wax emulsion which was recyclable and environmentally friendly. Water vapor transmission rate showed less than 50g/$m^2$.24hr in mixture ratio of 85:15, 87:13, 90:10. Especially the mixture ratio of 87:13 showed the most favorable water-vapor transmission rate. However, the moisture-proof layer was destroyed slightly by folding in packing. It has been observed that there was no close relationship between water-vapor transmission rate of the moisture-proof paper and grammage of the base paper, but the density of base paper had influenced on water vapor transmission rate. It was also observed that the moisture-proof paper could be recycled. The moisture-proof paper was similar to base paper in degree of the pulping, and there was no significant difference in dispersion between moisture-proof paper and base paper. Most of wax particles which caused the spots during drying process could be removed by flotation process. Tensile strength and tear strength of both moisture-proof paper and base paper after pulping were measured to examine the fiber bonding, and no significant difference in physical properties was observed.

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Water vapor barrier properties of polymer-like amorphous carbon deposited polyethylene naphthalate film

  • Kim, Jeong-Yong;Park, Gyu-Dae;Song, Ye-Seul;Lee, Hui-Jin;Vu, Minh Canh;Kim, Seong-Ryong
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.303.1-303.1
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    • 2016
  • Polymer-like amorphous carbon films were deposited on polyethylene naphthalate (PEN) substrate by plasma-enhanced chemical vapor deposition (PECVD) and their water vapor transmission rates (WVTR) were tested. propane was used as precursors. To make a polymer-like amorphous carbon film the deposition rate, surface roughness, light transmittance, and WVTR of the films were characterized as a function of the precursor feed ratio and plasma power. The water vapor transmission rates of bare PEN film and single layer PAC on PEN substrate were 6.95 g/m2/day and 0.3 g/m2/day, respectively. The superior property the water vapor permeability of thin layers of PAC was attributed to uniform coverage and good adhesion between PAC film and PEN substrate.

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Effect of Paper Properties on the Performance of a Enthalpy Exchanger (종이 물성이 전열교환 엘리먼트 성능에 미치는 영향)

  • Kim, Nae-Hyun;Cho, Jin-Pyo;Song, Gil-Sup;Kim, Dong-Hoon
    • Proceedings of the SAREK Conference
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    • pp.414-418
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    • 2008
  • The effects of paper properties such as density, air permeability, water vapor transmission rate on the thermal performance of plate-type enthalpy exchanger were experimentally investigated. Three enthalpy exchanger samples having different properties were made, and were tested according to the standard test procedure (KS B 6879). Effective efficiencies were defined, which accounted for the air leakage between supply and exhaust streams. Results showed that paper density affected the sensible heat transfer of the samples. Sensible heat transfer increased with density of the paper. It was also shown that water vapor transmission rate alone was not a proper indicator for the efficiency of latent heat transfer. Air permeability should also be considered for adequate evaluation of the latent heat transfer. Best performance was obtained for the sample having highest paper density and moderate water vapor transmission ratio.

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Performance of a Plate-Type Enthalpy Exchanger Made of Papers Having Different Properties (종이 물성에 따른 판형 전열교환기의 성능)

  • Kim, Nae-Hyun;Cho, Jin-Pyo;Song, Gil-Sup;Kim, Dong-Hoon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.8
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    • pp.547-555
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    • 2008
  • The effects of paper properties such as density, air permeability, water vapor transmission rate on the thermal performance of plate-type enthalpy exchanger were experimentally investigated. Papers having different properties were made from the same pulp by calendering or refining. Enthalpy exchanger samples were made from the papers, and were tested according to the standard test procedure (KS B 6879). Effective efficiencies were obtained, which accounted for the air leakage between supply and exhaust streams. Results showed that paper density affected the sensible heat transfer of the samples. Sensible heat transfer increased with density of the paper. It was also shown that effective efficiency of latent heat transfer was approximately the same independent of the samples, which suggests that papers made of the same pulp show similar water vapor transmission characteristics independent of the degree of calendering or refining. Best performance was obtained for the sample having highest paper density and moderate water vapor transmission ratio.

Improvement in the negative bias stability on the water vapor permeation barriers on Hf doped $SnO_x$ thin film transistors

  • Han, Dong-Seok;Mun, Dae-Yong;Park, Jae-Hyeong;Gang, Yu-Jin;Yun, Don-Gyu;Sin, So-Ra;Park, Jong-Wan
    • Proceedings of the Materials Research Society of Korea Conference
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    • pp.110.1-110.1
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    • 2012
  • Recently, advances in ZnO based oxide semiconductor materials have accelerated the development of thin-film transistors (TFTs), which are the building blocks for active matrix flat-panel displays including liquid crystal displays (LCD) and organic light-emitting diodes (OLED). However, the electrical performances of oxide semiconductors are significantly affected by interactions with the ambient atmosphere. Jeong et al. reported that the channel of the IGZO-TFT is very sensitive to water vapor adsorption. Thus, water vapor passivation layers are necessary for long-term current stability in the operation of the oxide-based TFTs. In the present work, $Al_2O_3$ and $TiO_2$ thin films were deposited on poly ether sulfon (PES) and $SnO_x$-based TFTs by electron cyclotron resonance atomic layer deposition (ECR-ALD). And enhancing the WVTR (water vapor transmission rate) characteristics, barrier layer structure was modified to $Al_2O_3/TiO_2$ layered structure. For example, $Al_2O_3$, $TiO_2$ single layer, $Al_2O_3/TiO_2$ double layer and $Al_2O_3/TiO_2/Al_2O_3/TiO_2$ multilayer were studied for enhancement of water vapor barrier properties. After thin film water vapor barrier deposited on PES substrate and $SnO_x$-based TFT, thin film permeation characteristics were three orders of magnitude smaller than that without water vapor barrier layer of PES substrate, stability of $SnO_x$-based TFT devices were significantly improved. Therefore, the results indicate that $Al_2O_3/TiO_2$ water vapor barrier layers are highly proper for use as a passivation layer in $SnO_x$-based TFT devices.

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Layer-by-layer assembled graphene oxide films and barrier properties of thermally reduced graphene oxide membranes

  • Kim, Seon-Guk;Park, Ok-Kyung;Lee, Joong Hee;Ku, Bon-Cheol
    • Carbon letters
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    • v.14 no.4
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    • pp.247-250
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    • 2013
  • In this study, we present a facile method of fabricating graphene oxide (GO) films on the surface of polyimide (PI) via layer-by-layer (LBL) assembly of charged GO. The positively charged amino-phenyl functionalized GO (APGO) is alternatively complexed with the negatively charged GO through an electrostatic LBL assembly process. Furthermore, we investigated the water vapor transmission rate and oxygen transmission rate of the prepared (reduced GO $[rGO]/rAPGO)_{10}$ deposited PI film (rGO/rAPGO/PI) and pure PI film. The water vapor transmission rate of the GO and APGO-coated PI composite film was increased due to the intrinsically hydrophilic property of the charged composite films. However, the oxygen transmission rate was decreased from 220 to 78 $cm^3/m^2{\cdot}day{\cdot}atm$, due to the barrier effect of the graphene films on the PI surface. Since the proposed method allows for large-scale production of graphene films, it is considered to have potential for utilization in various applications.

Thermal and Water Transmission Properties of Vapor Permeable Water Repellent Fabrics and Thermal Insulation Batting Materials (투습발수직물과 보온단열소재의 열 및 수분전달 특성)

  • Cho Gil Soo;Choi Jong Myoung;Lee Jung Ju;Lee Sern Woo
    • Journal of the Korean Society of Clothing and Textiles
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    • v.16 no.2
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    • pp.237-244
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    • 1992
  • The purpose of this study was to comparatively evaluate thermal and water transmission properties of several vapor permeable water repellent (VPWR) fabrics and synthetic battings that became available in recent years. Five VPWR fabrics evaluated were Hipora in three coating variants, $Gore-Tex^{\circledR}$ and $Aitace^{\circledR}$. Battings evaluated were $Viwarma^{\circledR}$, $Uniwarmr^{\circledR}$, $Thinsulate^{\circledR}$, and $Airseal^{\circledR}$ Thermal resistance and water vapor transmission were measured for each fabric and batting and in all combinations. Thermal resistance at zero and 37 cm/sec air velocity was determined by the Thermo Labo II technique for simultaneously measuring conduction and radiation heat transfer. Water vapor transmission over 24 hours was measured by a modified weight-gain method in a compact humid chamber at conditions simulating the clothing climate under heavy exercise ($40{\pm}1^{\circ}C$, $90{\pm}2\%$ R.H., and 0.5 m/sec air velocity). Fabric porosity was calculated from fiber density and fabric weight, thickness, and area. Thermal resistance results for the fabrics showed the effectiveness of coatings in inhibiting heat transfer. Measurements taken in wind were: $31.1\~37.6\%$ for $Hipora^{\circledR}$ variants; $31.0\%$ for $Gore-Tex^{\circledR}$; and $18.4\%$ for $Aitaca^{\circledR}$ Measurements without wind were higher but in the same order. Water vapor transmission results were in reverse order: $Aitac^{\circledR}$, $8.8 kg/m^{2};\;Gore-Tex^{\circledR}$, 6.4 kg/$m^{2}$; and $Hipora^{\circledR},\;4.4\~6.0\;kg/m^{2}$. In general thermal resistance increased with porosity. For battings, the thermal resistance with wind results were: $Viwarmu^{\circledR}$, $65.0\%;\; Thinsulate^{\circledR}$, $62.0\%$; $Uniwarm^{\circledR}$, $61.0\%$; and $Airseala^{\circledR},\;53.1\%$. Thermal resistance was proportional to thickness. Thermal resistance of fabric-batting combinations were $20\%$ higher than those of the battings only. Water vapor transmission for combinations was mainly affected by that for the VPWR fabric used.

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