Effect of specimen structural orientation on the moisture content ? water potential relationship of wood

Cloutier, Alain; Tremblay, Carl; Fortin, Yves

doi:10.1007/bf00202083

Cited by 6 publications

(4 citation statements)

References 12 publications

(22 reference statements)

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“…In addition, the absorption moisture contents measured in the present study is in the same range as the absorption data presented by Penner [16] and Fortin [17] for spruce and western hemlock respectively. The desorption data from the present study, to which the absorption measurements were compared, are in the same range as desorption results from previous studies performed on softwoods around 20ºC [16,17,20] as well as data for aspen sapwood [18,19] . However, there are two exceptions: Thygesen and Engelund [26] and Stone and Scallan [35] , in both these studies the desorption moisture contents are significantly lower.…”

Section: Comparison Of Resultssupporting

confidence: 67%

A Method for Determination of Absorption Isotherms at High Relative Humidity Levels: Measurements on Lime-Silica Brick and Norway Spruce (Picea abies(L.) Karst.)

Fredriksson

Johansson

2015

Drying Technology

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Link to publicationCitation for published version (APA): Fredriksson, M., & Johansson, P. (2016). A method for determination of absorption isotherms at high relative humidity levels: measurements on lime-silica brick and Norway spruce (Picea abies (L.) Karst.). Drying Technology, 34(1), 132-141. https://doi. AbstractThe relationship between the relative humidity and the moisture content of a material for relative humidity levels close to 100% can be studied using the pressure plate technique. However, this method is designed for desorption experiments and modifications are necessary in order to perform absorption experiments. This paper presents a method to condition samples to a uniform moisture content by absorption with the pressure plate technique. The specimens were suspended in magnetic clamps until the ceramic plate had equilibrated with the applied pressure and modifications were made so that water could circulate through the pressure plate cell.

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Section: Comparison Of Resultssupporting

confidence: 67%

A Method for Determination of Absorption Isotherms at High Relative Humidity Levels: Measurements on Lime-Silica Brick and Norway Spruce (Picea abies(L.) Karst.)

Fredriksson

Johansson

2015

Drying Technology

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“…The outflow of water from the extractors was checked 2-5 times a week, and the time to equilibrium was in each case 2-3 months. Only cylindrical samples were used for the PPT experiments, and they were always placed with one of the two flat faces facing the disk, i.e., water was made to move along the grain, which should ensure the shortest possible time to equilibrium (Cloutier et al 1995).…”

Section: Relative Humidity Levels and Equilibrium Moisture Contentsmentioning

confidence: 99%

Water sorption in wood and modified wood at high values of relative humidity. Part I: Results for untreated, acetylated, and furfurylated Norway spruce

Engelund²,

2010

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Desorption isotherms at 208C for untreated, acetylated, and furfurylated Norway spruce wPicea abies (L.) Karst.x sapwood were established in the 91.9-99.9% relative humidity (RH) range. Three methods were employed to secure various constant RH levels: saturated salt solutions, climate chambers, and the pressure plate technique. The curve form for the untreated samples did not show an upward bend, except perhaps above 99.5% RH, indicating that -contrary to what has hitherto been assumed -capillary condensation does not play a significant role for water sorption in wood below fiber saturation. Three additional results corroborate this conclusion: (1) calculation of the theoretical contribution of capillary condensation to the moisture content (MC) in wood based on idealized microstructural geometries by means of the Kelvin and Laplace equations resulted in very small contributions to the equilibrium moisture content (EMC), i.e., below 0.35% moisture at 99.9% RH. (2) The ratio between the EMC of acetylated and untreated samples did not show an increasing trend for increasing RH, as would have been the case if capillary condensation had taken place in both untreated and acetylated wood. (3) Low field time domain nuclear magnetic resonance results showed that only the relaxation curves from the furfurylated samples were affected systematically by freezing, indicating that neither untreated nor acetylated wood contained significant amounts of capillary condensed water.

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“…The result is a uniform distribution of both RH and moisture content within the specimens provided that the equilibration time is long enough. Although there are observations of moisture content gradients in specimens conditioned with pressure plate/pressure membrane measurements, they were attributed to lack of equilibrium (Cloutier and Fortin 1991;Cloutier et al 1995), i.e. too short equilibration times.…”

Section: Potential Differences In Moisture States Between the Conditioning Methodsmentioning

confidence: 99%

Artifacts in electrical measurements on wood caused by non-uniform moisture distributions

2020

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This paper examines how the moisture conditioning method affects the electrical conductance of wood. A widely used dataset was acquired by Stamm in 1929 who used a method of conditioning where water-saturated wood specimens were partially dried, sealed and left for a period of time for moisture to be redistributed before the electrical conductance was measured. However, more recent measurements combined conditioning above saturated salt solutions and pressure plate/pressure membrane techniques to obtain equilibrium moisture contents at constant relative humidity levels in the full moisture range. In this paper, the electrical conductance as a function of moisture content was compared for these two conditioning methods. When the specimens were conditioned to constant relative humidity levels, the data obeyed a percolation model better than when the conditioning procedure by Stamm was used. This was attributed to that Stamm’s method gives moisture gradients through the specimen because of sorption hysteresis effects, even though the wood is conditioned to a steady-state moisture content. Equilibration to constant relative humidity levels thus provided more well-defined moisture states and that the data followed a percolation model indicates that the mechanism of electrical conduction in wood does not change, even at high moisture contents.

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Effect of specimen structural orientation on the moisture content ? water potential relationship of wood

Cited by 6 publications

References 12 publications

A Method for Determination of Absorption Isotherms at High Relative Humidity Levels: Measurements on Lime-Silica Brick and Norway Spruce (Picea abies(L.) Karst.)

A Method for Determination of Absorption Isotherms at High Relative Humidity Levels: Measurements on Lime-Silica Brick and Norway Spruce (Picea abies(L.) Karst.)

Water sorption in wood and modified wood at high values of relative humidity. Part I: Results for untreated, acetylated, and furfurylated Norway spruce

Artifacts in electrical measurements on wood caused by non-uniform moisture distributions

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