THE PENETRATION OF WATER VAPOR INTO WOOD

1930 ◽  
Vol 2 (5) ◽  
pp. 318-326 ◽  
Author(s):  
L. M. Pidgeon ◽  
O. Maass
Keyword(s):  
Water Vapor ◽  
Moisture Content ◽  
Pressure Gradient ◽  
Wood Structure ◽  
Saturation Point ◽  
Vapor Diffusion ◽  
Careful Control ◽  
Spring Balance ◽  
The Difference ◽  
Natural Drying

The rate of diffusion of water vapor through wood has been studied through a comparison of the time taken for samples of various thickness to become saturated. This process is, in a sense, the converse of natural drying, and for comparative purposes is more amenable to careful control of pressure and temperature. Continuous measurements of the amount of adsorption were carried out by the use of a quartz spring balance completely enclosed in the apparatus at a constant vapor pressure.Comparative numerical values have been obtained of the rate of diffusion of water vapor through spruce (Picea canadensis) and pine (Pinus banxiana) in various directions, through heartwood and sapwood, and through samples of different lengths. The results are considered as evidence that the movement of water through wood at concentrations below the saturation point, takes place as vapor diffusion through the spaces of the wood structure due to the pressure gradient consequent on the difference of moisture content.

Hydration Chamber for Jeolco 200 Kv Microscope

1970 ◽  
Vol 28 ◽  
pp. 542-543
Author(s):  
V. R. Matricardi ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscope ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Pressure Gradient ◽  
Room Temperature ◽  
List Type ◽  
Type Number ◽  
Equilibrium Vapor Pressure

In order to observe room temperature hydrated specimens in an electron microscope, the following conditions should be satisfied: The specimen should be surrounded by water vapor as close as possible to the equilibrium vapor pressure corresponding to the temperature of the specimen.The specimen grid should be inserted, focused and photo graphed in the shortest possible time in order to minimize dehydration.The full area of the specimen grid should be visible in order to minimize the number of changes of specimen required.There should be no pressure gradient across the grid so that specimens can be straddled across holes.Leakage of water vapor to the column should be minimized.

Measurement and Modeling of Water-Vapor Diffusion in Elastomers with Impact in Humidity and Vacuum Measurements

2013 ◽  
Vol 34 (3) ◽  
pp. 412-423 ◽  
Author(s):  
Janez Šetina ◽  
Makfir Sefa ◽  
Bojan Erjavec ◽  
Domen Hudoklin
Keyword(s):  
Water Vapor ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion

Lime Plasters Containing Waste Ceramic Powder as Partial Replacement of Siliceous Aggregates

2014 ◽  
Vol 1035 ◽  
pp. 77-82 ◽  
Author(s):  
Eva Vejmelková ◽  
Monika Čáchová ◽  
Dana Koňáková ◽  
Pavel Reiterman ◽  
Robert Černý
Keyword(s):  
Water Vapor ◽  
Bending Strength ◽  
Ceramic Powder ◽  
Point Of View ◽  
Partial Replacement ◽  
Diffusion Resistance ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion ◽  
Hollow Brick ◽  
Lime Plaster

Waste materials are utilized with an increasing frequency in the building industry, during the last decades. The motivation is both environmental and economical. In this paper, waste ceramic powder produced at the grinding of hollow brick blocks used in precise-walling technologies, is applied as a partial replacement of siliceous aggregates of lime plasters. The designed plaster mixes are analyzed from the point of view of their basic physical, mechanical, hygric and thermal properties. The bulk density, matrix density, open porosity, compressive strength, bending strength, water vapor diffusion permeability, water vapor diffusion coefficient, water vapor diffusion resistance factor, thermal conductivity and specific heat capacity are the investigated parameters. A reference lime plaster is analyzed as well, for the sake of comparison. Experimental results show a remarkable enhancement of mechanical properties of the plasters with the increasing dosage of ceramic powder. Moreover, the thermal insulation properties are improved and the water vapor diffusion capability of the plasters with ceramic powder increases.

scholarly journals Moisture-Dependent Strength Properties of Thermally-Modified Fraxinus excelsior Wood in Compression

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1647 ◽  
Author(s):  
Edward Roszyk ◽  
Elżbieta Stachowska ◽  
Jerzy Majka ◽  
Przemysław Mania ◽  
Magdalena Broda
Keyword(s):  
Moisture Content ◽  
Strength Properties ◽  
Treatment Temperature ◽  
Thermal Modification ◽  
Fraxinus Excelsior ◽  
Mechanical Parameters ◽  
Saturation Point ◽  
Wood Moisture ◽  
Intrinsic Anisotropy ◽  
European Ash

European ash (Fraxinus excelsior L.) is one of the species commonly used for wood thermal modification that improves its performance. The presented research aimed to investigate a moisture-dependent strength anisotropy of thermally-modified European ash in compression. Wood samples were modified at 180 °C and 200 °C. Their mechanical parameters were determined in the principal anatomical directions under dry (moisture content of 3%) and wet (moisture content above fibre saturation point) conditions. Effect of heat treatment temperature and moisture content on the ash wood mechanical parameters concerning each anatomical direction were determined. The results show that thermal treatment kept the intrinsic anisotropy of wood mechanical properties. It decreased wood hygroscopicity, which resulted in improved strength and elasticity measured for wet wood when compared to untreated and treated samples. Higher treatment temperature (200 °C) increased wood elasticity in compression in all the anatomical directions despite wood moisture content during the measurements. Multivariate analysis revealed that the modification temperature significantly affected the modulus of elasticity perpendicular to the grain, while in the case of compression strength, the statistically significant effect was observed only parallel to the grain. The results obtained can be useful from an industrial perspective and can serve as part of a database for further modelling purposes.

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