Sorption isotherms of thermally modified wood

Olek, Wiesław; Majka, Jerzy; Czajkowski, Łukasz

doi:10.1515/hf-2011-0260

Cited by 82 publications

(39 citation statements)

References 30 publications

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“…MC difference between the absorption and desorption isotherms, but this result appears to be correlated with the general reduction in MC at given RH. A similar general reduction in MC is found for thermal modification of wood; however, this treatment appears to increase the absolute sorption hysteresis (Olek et al 2013). Automated sorption balances are useful for studies of sorption hysteresis, and several published studies have focused on this phenomenon.…”

Section: Automated Sorption Balancessupporting

confidence: 54%

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

2017

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Water plays a central role in wood research, since it affects all material properties relevant to the performance of wood materials. Therefore, experimental techniques for characterising water within wood are an essential part of nearly all scientific investigations of wood materials. This review focuses on selected experimental techniques that can give deeper insights into various aspects of water in wood in the entire moisture domain from dry to fully water-saturated. These techniques fall into three broad categories: (1) gravimetric techniques that determine how much water is absorbed, (2) fibre saturation techniques that determine the amount of water within cell walls, and (3) spectroscopic techniques that provide insights into chemical wood-water interactions as well as yield information on water distribution in the macro-void wood structure. For all techniques, the general measurement concept is explained, its history in wood science as well as advantages and limitations.

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Section: Automated Sorption Balancessupporting

confidence: 54%

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

2017

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“…Thermal modification reduced the equilibrium moisture content by about 50% for the highest temperature (240 °C) and the longest treatment time (5 h). This observation is consistent with the earlier findings of Metsä-Kortelainen et al (2006) and Olek et al (2013).…”

Section: Resultssupporting

confidence: 94%

“…Hill (2006) stated that hysteresis is reduced after thermal treatment, whereas Militz (2002) found no effect. Olek et al (2013) clearly demonstrated that the hysteresis coefficient increased with the modification temperature.…”

Section: Introductionmentioning

confidence: 89%

Effects of Cyclic Changes in Relative Humidity on the Sorption Hysteresis of Thermally Modified Spruce Wood

2016

Self Cite

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Thermal modification of spruce wood (Picea abies L.) was conducted at three different temperatures (160, 200, and 240 °C) and treatment times (1, 3, and 5 h). The cyclic sorption experiments were performed for relative humidity changes of 30 to 85%. The equilibrium moisture content of the thermally modified wood was reduced up to 50% after treatment at 240 °C for 5 h. The sorption isotherms were described with the Guggenheim, Anderson, and De Boer (GAB) model. Cyclic sorption increased the monolayer capacity. Thus, the monolayer sorption was increased, while the multilayer sorption was limited. The dependence of the mass loss, hysteresis loop, and the maximum difference of equilibrium moisture content on the modification temperature and duration was modeled by response surface methodology. There was a very strong correlation between the modification temperature and mass loss, while the relationship between treatment time and mass loss was insignificant. The correlations between the modification parameters and the descriptors of sorption hysteresis were stronger after cyclic sorption. The sorption hysteresis decreased after cyclic sorption. This result was mainly caused by the increase of the monomolecular sorption for the adsorption processes.

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“…More recently, TMT is also considered for indoor use, for instance, as parquet flooring or furniture (Militz 2008;Jones 2012). Higher durability as well as dimensional stability of TMT is closely related to lower water sorption (Tjeerdsma et al 1998;Welzbacher 2007;Olek et al 2013;Ringman et al 2013). In other words, the hygroscopicity of wood is reduced through thermal modification due to changes of chemical composition and structural changes of the cell wall.…”

Section: Introductionmentioning

confidence: 99%

Modeling the influence of thermal modification on the electrical conductivity of wood

Brischke¹,

Sachse²,

Welzbacher³

2013

Holzforschung

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Abstract:A model has been developed aiming at the description of the effect of thermal modification on the electrical conductivity of wood. The intention was to calculate the moisture content (MC) of thermally modified timber (TMT) through the parameters electrical resistance R, wood temperature T, and CIE L*a*b* color data, which are known to correlate well with the intensity of a heat treatment. Samples of Norway spruce (Picea abies Karst.) and beech (Fagus sylvatica L.) samples were thermally modified in laboratory scale at 11 different heat treatment intensities and the resistance characteristics of the samples were determined. Within the hygroscopic range, a linear relationship between the resistance characteristics and the mass loss (ML) through the heat treatment was established. Based on this, a model was developed to calculate MC from R, T, and ML. To validate this model, color values of 15 different TMTs from industrial production were determined for estimation of their ML and fed into the model. MC of the 15 arbitrarily heat-treated TMTs was calculated with an accuracy of ± 3.5% within the hygroscopic range. The material-specific resistance characteristics based on experimental data led to an accuracy of ± 2.5%.

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Sorption isotherms of thermally modified wood

Cited by 82 publications

References 30 publications

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

Effects of Cyclic Changes in Relative Humidity on the Sorption Hysteresis of Thermally Modified Spruce Wood

Modeling the influence of thermal modification on the electrical conductivity of wood

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