Densification of wood veneers combined with oil-heat treatment. Part 1: Dimensional stability

Fang, Carol; Cloutier, Alain; Blanchet, Pierre; Koubaa, Ahmed; Mariotti, Nicolas

doi:10.15376/biores.6.1.373-385

Cited by 33 publications

(22 citation statements)

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“…To combine favourable effects, some researchers have analysed the behaviour of wood subjected to densification and subsequently to OHT. Fang et al (2011) observed that in wood treated in this way the equilibrium moisture and the springback were reduced, and this reduction was greater in the samples treated with OHT at higher temperatures. Hsu et al (1988) and Laborie (2006) indicated that in this combined treatment there was a joint occurrence of a reversible swelling due to the hygroscopicity of the wood and another irreversible swelling due to the compression-set recovery.…”

Section: Obtained Increases In Moe Andmentioning

confidence: 86%

“…Hsu et al (1988) and Laborie (2006) indicated that in this combined treatment there was a joint occurrence of a reversible swelling due to the hygroscopicity of the wood and another irreversible swelling due to the compression-set recovery. Fang et al (2011) quantified the incidence of the irreversible swelling by performing saturation tests on the samples, and observed that it decreased as the time and the treatment temperature increased.…”

Section: Obtained Increases In Moe Andmentioning

confidence: 99%

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Simultaneous treatment with oil heat and densification on physical properties of Populus × Canadensis wood

Villasante

Vignote

Fernández-Serrano

et al. 2021

Maderas, Cienc. tecnol.

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Samples of wood from Populus × canadensis (9,5 % moisture) were treated with olive oil at 195 °C simultaneously with 15 % or 30 % compression densification, and the results were compared with samples subjected to oil heat treatment without densification, and control samples. The density of the treated samples increased by 18 %, 43 % and 1,5 % respectively, and barely changed over the six subsequent months stored inside the laboratory room (at approximately 65 % RH, 20 °C). This was due to the fact that the slight weight increment caused by the additional moisture content was offset by the increase in volume from the springback effect. When subjected to atmospheres with different relative humidities, the treated samples stabilised at the same time as the control samples, although the treated samples had a significantly lower moisture absorption than the control samples. It was also observed that the hygroscopic shrinkage in oil heat densification treatment samples was approximately half those of the control samples. The initial densification was partially lost as a result of springback: approximately 3 % in the first springback at a relative humidity of 65 % RH, and an additional 4 % in the second springback to a relative humidity of 85 % RH. Once this latter relative humidity had been attained, no new losses in densification were observed. The ageing of the oil used in the treatment caused a slight loss of densification in the densest samples.

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Section: Obtained Increases In Moe Andmentioning

confidence: 86%

Section: Obtained Increases In Moe Andmentioning

confidence: 99%

Simultaneous treatment with oil heat and densification on physical properties of Populus × Canadensis wood

Villasante

Vignote

Fernández-Serrano

et al. 2021

Maderas, Cienc. tecnol.

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“…The radial hardness values gradually decreased as the thermal treatment duration increased. However, the hardness value gradually decreased as the thermal treatment temperature and duration increased (Perçin 2012;Fang et al 2012b;Agnieszka 2017). The temperature and duration of the thermal treatment accounted for 30% of the wood hardness variability, whereas the interaction between temperature and duration accounted for 23% of the wood hardness variability (Agnieszka 2017).…”

Section: Radial Hardness Analysismentioning

confidence: 99%

Effects of thermo-hydro-mechanical treatments on various physical and mechanical properties of poplar (Populus) wood

Shao

Chen

et al. 2020

BioRes

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Poplar (Populus) wood was subjected in this work to thermo-hydro-mechanical treatment. The influence of the treatment parameters on the physical and mechanical properties were investigated. The wood samples were densified under three compression ratios (0%, 30%, and 50%), and thermally treated at three temperatures (180 °C, 200 °C, and 220 °C), at three thermal treatment durations (3 h, 4 h, and 5 h). The density, modulus of elasticity, modulus of rupture, radial hardness, and thickness swelling were measured. The results showed that the densities of the samples increased by 36.6% to 49.7%. As the compression rate increased, the temperature, duration, modulus of elasticity, modulus of rupture, and hardness increased. However, the dimensions of the densified samples were less stable. Compared to the densiﬁed samples, the maximum thickness swelling could be reduced by 74% (from 29.7% to 7.8%) when subjected to a thermal treatment at 220 °C for 3 h.

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“…However, in the densification processes, there is an increase in surface hardness [41][42][43][44][45]. In addition, it has been reported that both the modulus of elasticity and the modulus of rupture increase with the density [46][47][48][49]. Although these processes can improve certain properties in wood, they do not focus on increasing the stiffness.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Longitudinal Tensile Creep on the Stiffness of Radiata Pine (Pinus radiata D. Don)

et al. 2022

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The influence of load on the cellulose microfibrils of single cells or thin wood foils is known. It can decrease the cellulose microfibril angles and, in turn, increase the stiffness. However, this modification of a piece of wood, which is made up of multiple cells, is unknown. The aim of this research was to study the effect of tensile creep on the longitudinal stiffness of radiata pine wood. The modulus of elasticity of each specimen was determined before and after being subjected to tensile creep. The samples were loaded at 1170 N and 1530 N for 20 min at 70 °C. The load was determined as a function of a percentage of the force at the proportional limit. The moduli of elasticity before and post-tensile creep showed no effect on the stiffness of wood at the macroscopic level, but neither were there damage to the cell structure. It can be assumed that there are changes at the microscopic level, but they are not enough to be reflected at the macro scale. It is also challenging to achieve the modifications that occur at the level of a single cell or in thin wood foils; however, the implications of this would be favorable for the development of stronger wood-based products.

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Densification of wood veneers combined with oil-heat treatment. Part 1: Dimensional stability

Cited by 33 publications

References 0 publications

Simultaneous treatment with oil heat and densification on physical properties of Populus × Canadensis wood

Simultaneous treatment with oil heat and densification on physical properties of Populus × Canadensis wood

Effects of thermo-hydro-mechanical treatments on various physical and mechanical properties of poplar (Populus) wood

Effect of the Longitudinal Tensile Creep on the Stiffness of Radiata Pine (Pinus radiata D. Don)

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