Mass transfer of water vapor, carbon dioxide and oxygen on modified cellulose fiber-based materials

2012 ◽  
Vol 27 (2) ◽  
pp. 409-417 ◽  
Author(s):  
Alemayehu H. Bedane ◽  
Qinglin Huang ◽  
Huining Xiao ◽  
Mladen
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Water Vapor ◽  
Relative Humidity ◽  
Transmission Rate ◽  
The Other ◽  
Paper Sample ◽  
Coated Paper ◽  
Wide Range ◽  
Transfer Properties

Abstract Mass transfer properties of fibre network and coated paper are essential for understanding the barrier properties of the products and further advance in their application. In this study, different unmodified and coated papers, e.g., (Poly lactic acid (PLA), zein grafted paper) were prepared and characterized with regard to mass transfer properties. Water vapor, carbon dioxide (CO2) and oxygen (O2) transmission rates through the cellulose paper films were measured and the results discussed. The effects of sample film thickness and samples were found to be strongly dependent on the temperature and the relative humidity difference (mass transfer driving force). On the other hand water vapor permeabilities relative humidity. Water vapor diffusivities of the samples were also measured from the uptake rate measurements using Fickian diffusion slab model for a wide range of relative modified samples were found to be generally low compared to unmodified (reference) paper sample. Among the investigated samples, PLA/polyhedral oligomeric silsesquioxane POSS-bentonite modified paper sample showed higher mass transfer resistance to water vapour and the gases investigated in this study (CO2and O2). It showed lower water transmission rate (104 g/m2.day) compared to PLA-coated paper (130 g/m2.day), zein coated paper (179 g/m2.day) and control sample (359 g/m2.day) at the relative humidity gradient RH=74% and temperature of 25 oC. The oxygen transmission rate for PLA/(POSS-Bentonite) coated paper was found to be lower than for the other modified papers. Zein grafted paper showed better barrier property for water vapor than oxygen. Water vapor permeation through paper films shows an Arrhenius type of dependency with temperature, indicating activated process. The activation energies reveal diffusion dominated process for all paper samples investigated in this study, according to the solution-diffusion mechanism used to describe the permeation processes.

Mass Transfer From a Bubble in a Vertical Pipe

2011 ◽  
Author(s):  
Shogo Hosoda ◽  
Ryosuke Sakata ◽  
Kosuke Hayashi ◽  
Akio Tomiyama
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Bubble Diameter ◽  
Vertical Pipe ◽  
Oblate Spheroidal ◽  
Wide Range ◽  
Bubble Sizes ◽  
Small Bubbles ◽  
Taylor Bubbles

Mass transfer from single carbon dioxide bubbles in a vertical pipe is measured using a stereoscopic image processing method to develop a mass transfer correlation applicable to a wide range of bubble and pipe diameters. The pipe diameters are 12.5, 18.2 and 25.0 mm and the bubble diameter ranges from 5 to 26 mm. The ratio, λ, of bubble diameter to pipe diameter is therefore varied from 0.2 to 1.8, which covers various bubble shapes such as spherical, oblate spheroidal, wobbling, cap, and Taylor bubbles. Measured Sherwood numbers, Sh, strongly depend on bubble shape, i.e., Sh of Taylor bubbles clearly differs from those of spheroidal and wobbling bubbles. Hence two Sherwood number correlations, which are functions of the Peclet number and the diameter ratio λ, are deduced from the experimental data: one is for small bubbles (λ < 0.6) and the other for Taylor bubbles (λ > 0.6). The applicability of the proposed correlations for the prediction of bubble dissolution process is examined through comparisons between measured and predicted long-term bubble dissolution processes. The predictions are carried out by taking into account the presence of all the gas components in the system of concern, i.e. nitrogen, oxygen and carbon dioxide. As a result, good agreements for the dissolution processes for various bubble sizes and pipe diameters are obtained. It is also demonstrated that it is possible to evaluate an equilibrium bubble diameter and instantaneous volume concentration of carbon dioxide in a bubble using a simple model based on a conservation of gas components.

Effect of Anthocyanin Preparations as Colorants on Hygroscopicity of Dry-Pack Foods

1979 ◽  
Vol 42 (3) ◽  
pp. 225-227 ◽  
Author(s):  
F. M. CLYDESDALE ◽  
J. H. MAIN ◽  
F. J. FRANCIS ◽  
K. M. HAYES
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Transmission Rate ◽  
Packaging Material ◽  
Physical Parameters ◽  
Water Vapor Transmission Rate ◽  
Natural Colorants ◽  
Water Vapor Transmission ◽  
Grape Skins ◽  
Equilibrium Relative Humidity

The equilibrium relative humidity isotherm of a cherry beverage base and a strawberry gelatin dessert mix colored with anthocyanins from grape skins, cranberries and roselle was evaluated versus a Red No. 2 control. As well, the water vapor transmission rate of the packaging material was evaluated to evaluate probable shelf-life. Results indicated that physical parameters, such as hygroscopicity, must be considered in estimating effects of the use of natural colorants in foods as well as the color and chemical stability normally investigated.

scholarly journals Modeling Heat and Mass Transfer from Fabric-Covered Cylinders

2009 ◽  
Vol 4 (1) ◽  
pp. 155892500900400 ◽  
Author(s):  
Phillip Gibson
Keyword(s):  
Mass Transfer ◽  
Wind Speed ◽  
Relative Humidity ◽  
Heat And Mass Transfer ◽  
Material Properties ◽  
Laboratory Measurements ◽  
Transfer Properties

Fabric-covered cylinders are convenient analogs for clothing systems. The geometry is well defined and includes many of the effects that are important in garments. Fabric-covered cylinder models are used in conjunction with laboratory measurements of material properties to calculate heat and mass transfer properties of clothing under specific conditions of environmental wind speed, temperature, and relative humidity.

Water vapor sorption and diffusion in wheat straw particles and their impact on the mass transfer properties of biocomposites

2016 ◽  
Vol 133 (16) ◽  
pp. n/a-n/a ◽  
Author(s):  
Caroline Wolf ◽  
Valérie Guillard ◽  
Hélène Angellier-Coussy ◽  
Gabriella Ghizzi D. Silva ◽  
Nathalie Gontard
Keyword(s):  
Mass Transfer ◽  
Water Vapor ◽  
Wheat Straw ◽  
Water Vapor Sorption ◽  
Vapor Sorption ◽  
Transfer Properties ◽  
And Diffusion

Application of Chitosan as a Barrier Coating on Coated Ivory Board

2012 ◽  
Vol 200 ◽  
pp. 180-185 ◽  
Author(s):  
Zhi Qiang Fang ◽  
Gang Chen ◽  
Yu Sha Liu ◽  
Xin Sheng Chai
Keyword(s):  
Water Vapor ◽  
Double Layer ◽  
Transmission Rate ◽  
Single Layer ◽  
Barrier Properties ◽  
Vapor Permeability ◽  
Oxygen Barrier ◽  
Coated Paper ◽  
Oxygen Transmission Rate ◽  
Coating Weight

Chitosan solution was applied to coated ivory board as a barrier material, and the surface microstructure, oxygen resistance and water vapor permeability of chitosan-coated paper under different coating weight were studied. According to the images of scanning electron microscope(SEM) and Atomic force microscope(AFM), the coated ivory board surface has a smooth contour without pores and cracks after coating with chitosan. Increasing in coating hold-out of chitosan, the smoothness and the oxygen barrier properties of coated paper were improved considerably, but no improvement on water vapor resistance. An Oxygen transmission rate (OTR) of 119.0 cm3/m2•24h•0.1MPa was obtained when the coating weight of chitosan was 3.96 g/m2. Single-layer and double-layer techniques were used to coat coated ivory paper with chitosan; it was found that the OTR of paper, obtaining by double-layer coating technique, was lower than that of single-layer paper at similar coating weight. For the purpose of reducing water vapor transmission rate (WVTR) of chitosan-coated paper, Poly(vinyldene chloride)(PVDC) was applied on the chitosan-coated paper. Water vapor and oxygen barrier properties were enhanced as the coating weight of PVDC increased from 1.05 g/m2to 7.40 g/m2. While the chitosan and PVDC was coated on coated ivory paper through bi-layer technique for 1.96 g/m2and 7.40g/m2, respectively, the WVTR and OTR of paper decreased by 66.3% and 98.0% separately, compared to that of the chitosan-coated paper for 1.96g/m2.

PACKAGING: III. EFFECT OF MOULD GROWTH AND AGEING ON THE WATER-VAPOUR TRANSMISSION OF PACKAGING MATERIALS

1946 ◽  
Vol 24f (2) ◽  
pp. 117-122 ◽  
Author(s):  
C. G. Lavers ◽  
W. I. Illman
Keyword(s):  
Relative Humidity ◽  
Cellulose Acetate ◽  
Water Vapour ◽  
Transmission Rate ◽  
The Other ◽  
Packaging Materials ◽  
Metal Foil ◽  
Mould Growth ◽  
Coated Materials ◽  
Laminated Materials

Packaging materials were dusted with mould spores and stored in a cabinet at 95° F. and 95 to 100% relative humidity for periods of one to eight weeks.M.S.T. and M.S.A.T. "Cellophane" were attacked only slightly by mould, but deterioration of the heat-sealing, moisture-proof lacquer occurred during storage under conditions suitable for optimum mould growth. Moulds grew abundantly on M.S.Y.T. Cellophane. Wax-coated materials supported abundant mould growth, and their water-vapour transmission values increased when wax peeled from the surface of the sheet. The transmission rate of laminated materials having metal foil as one layer was not greatly affected by mould growth or delamination of the other layers. Abundant mould growth developed on most samples of kraft, and on glassine. Very little mould developed on cellulose acetate, Pliofilm, or vinyl-film.

scholarly journals Measurement of the dynamic moisture buffering potential of fabrics

2018 ◽  
Vol 89 (5) ◽  
pp. 739-747 ◽  
Author(s):  
Geoffrey RS Naylor
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Natural Fibers ◽  
Test Sample ◽  
Fiber Types ◽  
Fixed Temperature ◽  
New Approach ◽  
Synthetic Fibers ◽  
Wide Range ◽  
Moisture Buffering

In non-stationary wear conditions, characterized by intermittent pulses of moderate or heavy sweating, a garment with a good moisture buffering action can improve comfort. This is consistent with the common consumer belief that clothing manufactured from hygroscopic natural fibers (e.g., wool or cotton) provides better breathability. The current work describes a new approach for measuring dynamic moisture buffering potential using the sweating guarded hotplate instrument in a novel mode of operation. A fabric test sample is placed on the hotplate following the normal procedure for dry mode testing but with the relative humidity of the surrounding environment set to a low value (45%). After equilibration, the relative humidity is rapidly increased to a high value (85%). In the case of hygroscopic samples, a transient reduction in the heat required to maintain the hotplate at its fixed temperature is observed. It is demonstrated that the area of this transient peak is a measure of the water vapor absorbed during this transition, that is, the moisture buffering potential of the test specimen. A key to this new approach is that the heat of sorption per gram of water vapor absorbed is approximately the same for a wide range of natural and synthetic fibers commonly used in clothing. Using matched knitted fabrics manufactured from wool, cotton or polyester, the technique detected the heat released from light weight fabrics and the performance of the different fiber types is clearly distinguished.

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