Strength properties of thermally modified softwoods and its relation to polymeric structural wood constituents

Boonstra, Michiel J.; Acker, Joris Van; Tjeerdsma, Bôke F.; Kegel, Edo V.

doi:10.1051/forest:2007048

Cited by 306 publications

(300 citation statements)

References 31 publications

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“…In another study, the density of Scots pine and Norway spruce also had 10% and 8.5% density reduction, respectively, as a result of heat treatment (Boonstra et al 2007). Degradation of hemicellulose into volatile substances and evaporation of extractives are the primary parameters responsible for the density reduction of wood when heat treated (Esteves and Pereira 2009).…”

Section: Resultsmentioning

confidence: 99%

Selected Properties of Heat-Treated Eastern Red Cedar (Juniperus virginiana L.) Wood

Korkut¹,

Hızıroǧlu²

2013

BioResources

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The objective of this study was to evaluate the effect of heat treatment on properties including oven-dry density, weight loss, surface roughness, shear strength, and hardness of eastern red cedar (Juniperus virginiana L.). The anatomical structures of samples were also examined by scanning electron microscope (SEM). Two different heat treatment schedules, with temperatures of 130°C and 160°C and 3 and 7 h exposure times, were considered for the experiment. A stylus method was employed to evaluate the surface properties of heat-treated samples. Three roughness parameters, average roughness (R a ), mean peak-to-valley height (R z ), and maximum roughness (R max ), were determined from the surface of specimens and used to evaluate the effect of heat treatment on the surface properties. The shear strength of samples bonded with polyvinyl acetate (PVAc) adhesive was also measured. All properties of the samples exposed to different heat treatment schedules were significantly different (p = 0.05) from each other. The results of this study demonstrated that the oven-dry density, surface roughness, shear strength, and hardness of the samples decreased, while their weight loss increased slightly, with increasing heat treatment temperature and time.

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Section: Resultsmentioning

confidence: 99%

Selected Properties of Heat-Treated Eastern Red Cedar (Juniperus virginiana L.) Wood

Korkut¹,

Hızıroǧlu²

2013

BioResources

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“…From the glassy state (0 °C) to the rubbery state (130 °C), heat treated wood at 200 °C for 120 min has the highest stiffness. Boonstra et al (2007) observed that thermally treated Scots pine and radiata pine at 165 °C had a 10 and 13% increase in the modulus of elasticity, respectively. They further remarked that the increase of the MOE (26%) of the radiata pine occurred when the hydrothermolysis treatment temperature was raised to 175 °C.…”

Section: Rheological Propertiesmentioning

confidence: 98%

“…They further remarked that the increase of the MOE (26%) of the radiata pine occurred when the hydrothermolysis treatment temperature was raised to 175 °C. Boonstra et al (2007) suggested that because wood polymers are inter-related and networked, a heat treatment method which affects the individual wood components and their interaction is bound to affect the mechanical properties of wood. Hirai et al (1972) observed that the wood dynamic elastic modulus slightly increased after about 100 hours' heating at the relatively low temperature of 100 °C, corresponding to the increase in the cellulose crystallinity.…”

Section: Rheological Propertiesmentioning

confidence: 99%

Mid-infrared spectroscopy and dynamic mechanical analysis of heat-treated obeche (Triplochiton scleroxylon)wood

Fabiyi

Ogunleye

2015

Maderas, Cienc. tecnol.

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The chemical structure change and rheological behaviour of heat-treated Obeche (Triplochiton scleroxylon) wood were investigated. Wood samples were treated at 160 and 200°C for 30, 60 and 120 minutes. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and dynamic mechanical analysis (DMA) were employed to characterize the chemical structure and rheological property of the heat-treated wood, respectively. Infrared data showed that there was a reduction in the number of hydroxyl groups (one of the factors normally attributed to water absorption) of heat treated wood relative to the control samples. The relative cellulose crystallinity increased slightly which may be one of the factors contributing to the stiffness of the heat-treated wood. The latter increases with increasing treatment temperature and time. The rheological properties of the wood samples were tested while submerged in N-methyl-2-pyrrolidone solvent under saturated conditions. DMA results showed that the increasing heat treatment time caused an increase in the glass transition temperature relative to the control sample, irrespective of the treatment temperature. Therefore, heat treatment at moderately high temperatures (160 and 200 °C) showed an interesting potential which could be used to reduce water absorption and improve flexural modulus of Obeche wood.

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“…Previous studies have indicated that MOE and MOR in Bending strength decrease as a function of the increased treatment severity (Mburu et al 2008). In addition, the influence of heat treatment on different strength properties is not proportional (Boonstra et al 2007). These mechanical modifications depend on the wood species nature (Arnold 2010) but also on the natural defects, such as knots, resin pockets.…”

Section: Evaluation Of Mechanical Propertiesmentioning

confidence: 99%

“…These mechanical modifications depend on the wood species nature (Arnold 2010) but also on the natural defects, such as knots, resin pockets. Wood strength properties appeared to be affected by the heat treatment (Boonstra et al 2007). These observations may explain the scatter of results and consequently the lower value of the determination coefficients (0,60 < R 2 < 0,98, Figures 5-6).…”

Section: Evaluation Of Mechanical Propertiesmentioning

confidence: 99%

Utilization of temperature kinetics as a method to predict treatment intensity and corresponding treated wood quality: Durability and mechanical properties of thermally modified wood

Candelier

Hannouz

Elaieb

et al. 2015

Maderas, Cienc. tecnol.

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Wood heat treatment is an attractive alternative to improve decay resistance of wood species with low natural durability. However, this improvement of durability is realized at the expense of the mechanical resistance. Decay resistance and mechanical properties are strongly correlated to thermal degradation of wood cells wall components. Mass loss resulting from this degradation is a good indicator of treatment intensity and final treated wood properties. However, the introduction of a fast and accurate system for measuring this mass loss on an industrial scale is very difficult. Nowadays, many studies are conducted on the determination of control parameters which could be correlated with the treatment conditions and final heat treated wood quality such as decay resistance. The aim of this study is to investigate the relations between kinetics of temperature used during thermal treatment process representing heat treatment intensity, mass losses due to thermal degradation and conferred properties to heat treated wood. It might appear that relative area of treatment temperature curves is a good indicator of treatment intensity. Heat treatment with different treatment conditions (temperature-time) have been performed under vacuum, on four wood species (one hardwood and three softwoods) in order to obtain thermal degradation mass loses of 8, 10 and 12%. For each experiment, relative areas corresponding to temperature kinetics, mass loss, decay resistance and mechanical properties have been determined. Results highlight the statement that the temperature curves' area constitutes a good indicator in the prediction of needed treatment intensity, to obtain required wood durability and mechanical properties such as bending resistance and Brinell hardness.

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Strength properties of thermally modified softwoods and its relation to polymeric structural wood constituents

Cited by 306 publications

References 31 publications

Selected Properties of Heat-Treated Eastern Red Cedar (Juniperus virginiana L.) Wood

Selected Properties of Heat-Treated Eastern Red Cedar (Juniperus virginiana L.) Wood

Mid-infrared spectroscopy and dynamic mechanical analysis of heat-treated obeche (Triplochiton scleroxylon)wood

Utilization of temperature kinetics as a method to predict treatment intensity and corresponding treated wood quality: Durability and mechanical properties of thermally modified wood

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