Monitoring electrical properties of thermally modified wood as a possible tool for quality assessment

Holzforschung ◽  
2016 ◽  
Vol 70 (4) ◽  
pp. 351-359 ◽  
Author(s):  
Wang Wang ◽  
Yuan Zhu ◽  
Jinzhen Cao ◽  
Pascal D. Kamdem
Keyword(s):  
Mechanical Properties ◽  
Electrical Properties ◽  
Electrical Resistance ◽  
Close Relation ◽  
Modulus Of Rupture ◽  
Bending Properties ◽  
Polar Groups ◽  
Mobility Of Ions ◽  
Thermally Modified Wood ◽  
Modified Wood

Abstract The electrical properties of thermally modified wood (TMW) of southern pine (Pinus spp.) have been investigated, while the samples were modified at 150°C, 175°C, 200°C, and 225°C for 4 h. After conditioning the samples at five relative humidities, the constants for electrical resistance (kR) and dielectricity (kP) were measured and calculated according to the model “electrical properties vs. moisture content”. The correlations between kR and kP and mass loss (ML), CIEL*a*b* color and bending properties in terms of modulus of rupture and modulus of elasticity were established. The coefficients of determination (R2) between these parameters were found to be between 0.926 and 0.999. TM influenced both kR and kP via changing the concentration and mobility of ions inside the wood and decreasing amount of polar groups of wood polymers. The conclusion is that the severity of TM such as the mechanical properties of TMW is in a close relation to the electrical properties.

scholarly journals Particleboards from Recycled Thermally Modified Wood

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1462
Author(s):  
Ján Iždinský ◽  
Zuzana Vidholdová ◽  
Ladislav Reinprecht
Keyword(s):  
Mechanical Properties ◽  
Urea Formaldehyde ◽  
Brown Rot ◽  
Decay Resistance ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Negative Effect ◽  
Serpula Lacrymans ◽  
Thermally Modified Wood ◽  
Modified Wood

In recent years, the production and consumption of thermally modified wood (TMW) has been increasing. Offcuts and other waste generated during TMWs processing into products, as well as already disposed products based on TMWs can be an input recycled raw material for production of particleboards (PBs). In a laboratory, 16 mm thick 3-layer PBs bonded with urea-formaldehyde (UF) resin were produced at 5.8 MPa, 240 °C and 8 s pressing factor. In PBs, the particles from fresh spruce wood and mixed particles from offcuts of pine, beech, and ash TMWs were combined in weight ratios of 100:0, 80:20, 50:50 and 0:100. Thickness swelling (TS) and water absorption (WA) of PBs decreased with increased portion of TMW particles, i.e., TS after 24 h maximally about 72.3% and WA after 24 h maximally about 64%. However, mechanical properties of PBs worsened proportionally with a higher content of recycled TMW—apparently, the modulus of rupture (MOR) up to 55.5% and internal bond (IB) up to 46.2%, while negative effect of TMW particles on the modulus of elasticity (MOE) was milder. Decay resistance of PBs to the brown-rot fungus Serpula lacrymans (Schumacher ex Fries) S.F.Gray increased if they contained TMW particles, maximally about 45%, while the mould resistance of PBs containing TMW particles improved only in the first days of test. In summary, the recycled TMW particles can improve the decay and water resistance of PBs exposed to higher humidity environment. However, worsening of their mechanical properties could appear, as well.

Using Fourier Transform Near-Infrared Spectroscopy to Predict the Mechanical Properties of Thermally Modified Southern Pine Wood

2016 ◽  
Vol 70 (10) ◽  
pp. 1676-1684
Author(s):  
Li Tong ◽  
Wenbo Zhang
Keyword(s):  
Mechanical Properties ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Modulus Of Rupture ◽  
Coefficient Of Determination ◽  
Southern Pine ◽  
Pine Wood ◽  
Close Relationship ◽  
Thermally Modified Wood ◽  
Modified Wood

This study seeks to estimate the mechanical properties of thermally modified wood (TMW) using near-infrared (NIR) spectroscopy to measure 80 samples in three-point bending tests. Near-infrared spectra collected from the transverse, radial, and tangential sections of wood, coupled with chemometric techniques, were used to predict the mechanical properties of southern pine wood, from which NIR models were constructed based on partial least squares and corresponding cross-validation. The coefficient of determination between NIR transverse section spectra, as well as two mechanical properties of wood samples, modulus of rupture (MOR) and modulus of elasticity (MOE), were above 0.92 and greater than values for other sections. Spectral data from the transverse sections were richer than data from other sections, and thus, a model based on transverse sections better predicts the mechanical properties of wood. A close relationship between the values for mechanical properties (MOE and MOR) and the NIR spectra of thermally modified southern pine wood can be demonstrated, which provides the potential to predict the mechanical properties of untreated and thermally modified wood.

scholarly journals Chemical composition as factor affecting the mechanical properties of thermally modified black poplar (Populus nigra L.)

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3915-3929
Author(s):  
Paweł Kozakiewicz ◽  
Michał Drożdżek ◽  
Agnieszka Laskowska ◽  
Marek Grześkiewicz ◽  
Olga Bytner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Thermal Processing ◽  
Wood Properties ◽  
Populus Nigra ◽  
Modulus Of Rupture ◽  
Wood Moisture ◽  
Black Poplar ◽  
Thermally Modified Wood ◽  
Modified Wood

Black poplar (Populus nigra L.) was thermally modified in superheated steam at 160 °C, 190 °C, and 220 °C for 2 h. The research identified correlations between the chemical composition and selected mechanical properties of thermally modified wood. The higher treatment temperatures significantly lowered the modulus of rupture (MOR) and the Brinell hardness (BH). These correlations were particularly apparent at higher temperatures (190 °C and 220 °C) when thermally modified wood experienced stronger hemicelluloses degradation, which was indicated by an increase in the content of non-structural substances. The wood properties including compressive strength parallel to the grain (CS), modulus of elasticity during bending (MOE), and compressing (MCS) were affected less by the chemical changes caused by the thermal processing of wood. Moreover, the level of wood moisture content also affected these changes.

Impact of thermally modified wood on mechanical properties of mortar

2019 ◽  
Vol 208 ◽  
pp. 413-420 ◽  
Author(s):  
Aofei Guo ◽  
Osama Bu Aamiri ◽  
Jagannadh Satyavolu ◽  
Zhihui Sun
Keyword(s):  
Mechanical Properties ◽  
Thermally Modified Wood ◽  
Modified Wood

Influence of Different Modifications on Bending Strength of Wood

2019 ◽  
Vol 800 ◽  
pp. 240-245
Author(s):  
Andis Antons ◽  
Dace Cīrule ◽  
Ingeborga Andersone ◽  
Anrijs Verovkins ◽  
Edgars Kuka
Keyword(s):  
Thermal Treatment ◽  
Bending Strength ◽  
Treatment Method ◽  
Thermal Modification ◽  
Wood Products ◽  
Bending Properties ◽  
Wood Protection ◽  
Thermally Modified Wood ◽  
Mild Temperature ◽  
Modified Wood

Despite intensive research in wood protection, no simple wood treatment method is available for satisfactory wood protection that could ensure appropriate strength and bio-resistance of wood products during their service life. The present study is a part of a project that is aimed to improve wood service properties by combining wood thermal treatment and impregnation with copper containing preservatives. The objective of the present study was to investigate the effect of conventional modifications (thermal modification at relatively mild temperature range (150 - 180°C) and impregnation) and double-treatments (impregnation after thermal treatment and vice versa) on the bending properties of birch (Betula spp.) and pine (Pinussylvestris L.) wood. Bending strength considerably decreased after thermal modification of wood, however MOE values generally did not significantly change. Moreover, impregnation had no effect on the bending properties for both unmodified and thermally modified wood specimens. For double-treatment in which impregnation was carried out before thermal modification no changes in bending strength were observed comparing to thermally modified wood. However, MOE values of these specimens were 10 % for birch and 19 % for pine smaller comparing to just thermally modified wood. The results of double-treatment tests imply that, regarding wood bending properties, wood impregnation after thermal modification is more appropriate.

Prediction of physical and mechanical properties of thermally modified wood based on color change evaluated by means of “group method of data handling” (GMDH) neural network

Holzforschung ◽  
2019 ◽  
Vol 73 (4) ◽  
pp. 381-392 ◽  
Author(s):  
Vahid Nasir ◽  
Sepideh Nourian ◽  
Stavros Avramidis ◽  
Julie Cool
Keyword(s):  
Neural Network ◽  
Mechanical Properties ◽  
Color Change ◽  
Physical And Mechanical Properties ◽  
Group Method ◽  
Data Handling ◽  
Color Parameters ◽  
Swelling Coefficient ◽  
Thermally Modified Wood ◽  
Modified Wood

AbstractThe effect of thermal modification (TM) on the color of western hemlock wood and its physical and mechanical properties were investigated. The focus of this study was the prediction of material properties of thermally modified wood based on the color change via the “group method of data handling (GMDH)” neural network (NN). The NN was trained by color parameters for predicting the equilibrium moisture content (EMC), density, porosity, water absorption (WA), swelling coefficient, dynamic modulus of elasticity (MOEdyn) and hardness. The color parameters showed a significant correlation with temperature and are well correlated with the heat treatment (HT) intensity. Color parameters combined with the GMDH-type NN successfully predicted the physical properties of the material. The best correlation was achieved with the swelling coefficient, EMC and WA. All these properties were significantly influenced by HT. The color parameters did not seem suitable for predicting the wood hardness and MOEdyn. The GMDH NN shows a higher model accuracy than the multivariate linear and partial least squares (PLS) regression models.

scholarly journals Physical and Mechanical Properties of Poplar Wood Modified by Glucose-Urea-Melamine Resin/Sodium Silicate Compound

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 127
Author(s):  
Qiangqiang Liu ◽  
Haojia Du ◽  
Wenhua Lyu
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Sodium Silicate ◽  
Physical And Mechanical Properties ◽  
Modulus Of Rupture ◽  
Infrared Analysis ◽  
Poplar Wood ◽  
Melamine Resin ◽  
Characteristic Structure ◽  
Modified Wood

In order to improve the performance of soft plantation wood, an environmentally friendly wood modifier was developed. First, using urea and melamine as crosslinking agents, the glucose-urea-melamine resin (MUG) was prepared with glucose under the catalysis of inorganic acid and metal ions. Then MUG, sodium silicate, and distilled water were mixed and stirred at 40 °C to prepare MUG resin/sodium silicate compound modifier (G20S10, G10S20, the subscript number represents the mass percentage of the component in the solution.). Then plantation poplar wood (Populus tomentosa) was impregnated and modified with them. Their physical and mechanical properties were tested and compared with those of the wood treated with sodium silicate of 20% mass fraction (S20). Infrared analysis showed that the amino resin characteristic structure (CO-NH-) existed in MUG, and the absorption peak of the furan ring (C=C) appeared. Compared with S20 modified wood, the shrinkage degree of G10S20 or G20S10 modified wood is reduced, their moisture absorption is decreased, and their dimensional stability is improved. MUG resin/sodium silicate compound modifier can effectively enhance the wood’s density, modulus of elasticity, modulus of rupture, and compression strength. SEM analysis showed that there were columnar and granular solid substances attached to the cell wall, cell lumen, intercellular space, and vessel of G20S10 modified wood. EDX showed that the number of Si elements on the cell wall was significantly increased compared with the control, indicating that the modifier effectively entered the wood cell wall. The G20S10 can greatly improve the wood’s physical and mechanical properties through an organic–inorganic compound synergistic effect. It is a green, non-formaldehyde, low cost wood modifier with broad application prospects.

The toughness of hygrothermally modified wood

Holzforschung ◽  
2015 ◽  
Vol 69 (7) ◽  
pp. 851-862 ◽  
Author(s):  
Mark Hughes ◽  
Callum Hill ◽  
Alexander Pfriem
Keyword(s):  
Mechanical Properties ◽  
Coupling Agent ◽  
Thermal Modification ◽  
Point Of View ◽  
Interfacial Coupling ◽  
Modification Process ◽  
Thermally Modified Wood ◽  
Wall Components ◽  
Modified Wood

Abstract The mechanical properties of thermally modified wood are discussed with regard to toughness. The molecular origins of the mechanical properties and, in particular, the role of the hemicelluloses are considered. The important role of water and its interaction with the cell wall components is also examined. The properties are discussed from the point of view of composite theory, with the three main macromolecular components acting as reinforcement, matrix and interfacial coupling agent. The important role that hemicelluloses play as a coupling agent between the cellulosic microfibril reinforcement and the lignin-rich matrix is highlighted. Destruction of the hemicelluloses during the thermal modification process has a profound effect upon the mechanical behaviour.

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