scholarly journals Evaluation of the Dimensional Stability of Black Poplar Wood Modified Thermally in Nitrogen Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1491
Author(s):  
Olga Bytner ◽  
Agnieszka Laskowska ◽  
Michał Drożdżek ◽  
Paweł Kozakiewicz ◽  
Janusz Zawadzki
Keyword(s):  
Dimensional Stability ◽  
Nitrogen Atmosphere ◽  
Thermal Modification ◽  
Poplar Wood ◽  
Dimensional Changes ◽  
Processing Times ◽  
Modification Process ◽  
Black Poplar ◽  
Tangential Directions ◽  
Modified Wood

Black poplar (Populus nigra L.) was thermally modified in nitrogen atmosphere. The effects of the modification process on poplar wood were evaluated for temperatures: 160 °C, 190 °C, and 220 °C applied for 2 h; and 160 °C and 190 °C for 6 h. The percentual impact of temperature and time of modification on the properties of modified wood was analysed. The study permitted the identification correlations between the chemical composition and selected physical properties of thermally modified poplar wood. The dimensional stability of poplar wood was improved after thermal modification in nitrogen. The higher the temperature of modification, the lower the equilibrium moisture content (EMC) of black poplar. At the temperature of 220 °C, EMC was two times lower than the EMC of non-modified black poplar. It is also possible to reduce the dimensional changes of wood two-fold (at the modification temperature of 220 °C), both in radial and tangential directions, independently of the acclimatization conditions (from 34% to 98% relative humidity, RH). Similar correlations have been found for wood that has been soaked in water. Higher modification temperatures and longer processing times contributed to a lower swelling anisotropy (SA).

Dimensional Stability of Poplar Wood after Densification Combined with Heat Treatment

2012 ◽  
Vol 152-154 ◽  
pp. 112-116 ◽  
Author(s):  
Jia Bin Cai ◽  
Tao Ding ◽  
Liu Yang
Keyword(s):  
Heat Treatment ◽  
Dimensional Stability ◽  
Hybrid Poplar ◽  
Treatment Temperature ◽  
Thermal Modification ◽  
Holding Time ◽  
Poplar Wood ◽  
Compression Set ◽  
Densification Temperature

Hybrid poplar boards were subjected to thermo-mechanical densification combined with heat treatment. Hydroscopicity and hygroscopicity of the treated samples were measured. The results showed that dimensional stability of the samples was influenced by compression set significantly. The higher the compression set, the greater the swelling of the samples. On the contrary, the influence of densification temperature and duration was not significant. Thermal modification significantly reduced hydroscopicity and hygroscopicity of the samples. Both higher treatment temperature and longer holding time resulted in better dimensional stability.

Hygroscopic properties of thermally modified false Iroko [Antiaris toxicara (Lesch)]

2021 ◽  
Vol 18 (1) ◽  
pp. 51-57
Author(s):  
F.A. Faruwa ◽  
K. Duru
Keyword(s):  
Weight Loss ◽  
Dimensional Stability ◽  
Thermal Process ◽  
Colour Change ◽  
Wood Properties ◽  
Thermal Modification ◽  
Hygroscopic Properties ◽  
Different Temperatures ◽  
Thermally Modified Wood ◽  
Modified Wood

The study investigated the use of thermal modification to improve the hygroscopic properties of False Iroko [Antiaris toxicaria (Lesch)]. Samples of Antiaris toxicara Lesch wood were subjected to thermal modification in a furnace at temperatures of 160, 180 and 200°C for 30 and 60 minutes. Results showed that wood properties were improved with exposure to different temperatures. Subsequent to the thermal process, a colour change from pale yellow to darkish brown was observed progressively with increase in temperature, accompanied by a weight loss in the range of 12.08% to 23.67%. The outcome of these treatments resulted in a decrease in volumetric swelling and increase in dimensional stability of modified wood; this can be attributed to observed decrease in moisture intake. The thermal modification of Antiaris toxicara Lesch wood affected the dimensional stability properties. Thus, due to significant changes via modification carried out on the selected species which is classified as lesser utilized wood species, lesser utilized wood,Antiaristoxicara Lesch wood is recommended for use due to its efficient dimensional stability after modification . keywords:, Thermally modified wood ;False Iroko

Dynamic moisture sorption and dimensional stability of furfurylated wood with low lignin content

Holzforschung ◽  
2019 ◽  
Vol 74 (1) ◽  
pp. 68-76
Author(s):  
Tiantian Yang ◽  
Erni Ma ◽  
Jinzhen Cao
Keyword(s):  
Relative Humidity ◽  
Dimensional Stability ◽  
Furfuryl Alcohol ◽  
Lignin Content ◽  
Moisture Sorption ◽  
Dimensional Change ◽  
Poplar Wood ◽  
Sorption Coefficient ◽  
Dimensional Changes ◽  
Sinusoidal Shape

AbstractDegradation of lignin occurs naturally in wood due to the influence of microorganisms or photic radiation. To improve the properties of wood with low lignin content, furfuryl alcohol (FA) at the concentration of 25% was used to modify poplar wood (Populus euramericana Cv.) after partial delignification. Moisture sorption and dimensional stability of the samples were investigated under dynamic conditions where the relative humidity (RH) was changed sinusoidally between 45% and 75% at 25°C. Both the moisture content (MC) and the tangential dimensional change varied with a sinusoidal shape similar to the RH. Hygroscopicity and hygroexpansion increased after delignification, while furfurylation led to an inverse impact by reducing MC, dimensional changes, amplitudes of MC and dimensional changes, moisture sorption coefficient (MSC), and humidity expansion coefficient (HEC). After delignification and further furfurylation, the MC and the dimensional changes were reduced by about 20%, and the maximum drop in amplitudes of MC and dimensional changes was about 30%, while the MSC and the HEC decreased by over 15%. In addition, the furfurylated wood with low lignin content exhibited lower sorption hysteresis and swelling hysteresis.

Thermal modification of Southern pine combined with wax emulsion preimpregnation: effect on hydrophobicity and dimensional stability

Holzforschung ◽  
2015 ◽  
Vol 69 (4) ◽  
pp. 405-413 ◽  
Author(s):  
Wang Wang ◽  
Yuan Zhu ◽  
Jinzhen Cao ◽  
Xi Guo
Keyword(s):  
Water Absorption ◽  
Dimensional Stability ◽  
Photoelectron Spectroscopy ◽  
Water Repellency ◽  
Solid Content ◽  
Thermal Modification ◽  
Paraffin Wax ◽  
Southern Pine ◽  
Thermally Modified Wood ◽  
Modified Wood

Abstract The aim of this study was to enhance the water repellency and dimensional stability of thermally modified wood by combining the preimpregnation of paraffin wax emulsion. To achieve this, Southern pine (SP; Pinus spp.) samples were first impregnated with paraffin wax emulsion (with 2.0% solid content) and then subjected to thermal modification (TM) in an oven at 180°C and 220°C for 4 and 8 h. The contact angle (CA), surface free energy, water absorption rate (WAR), anti-swelling efficiency (ASE), and bending properties of the control and modified samples were investigated. Moreover, the chemical and morphological alterations were analyzed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Both the wax impregnation and TM decreased the surface wettability, water absorption, and tangential swelling, while the combination of wax and thermal treatment exhibited the best water repellency and dimensional stability, indicating the synergism between the two procedures. However, the wax preimpregnation did not affect the mechanical properties of thermally modified wood. The FTIR, SEM, and XPS analyses confirmed that the synergistic effect is mainly due to the redistribution of the paraffin wax during TM rather than its impact on the chemical changes caused by thermal degradation.

scholarly journals Effects of Thermo-Vibro-Mechanic® densification on the density and swelling of pre-treated Uludağ fir and black poplar wood

BioResources ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. 1581-1599
Author(s):  
Mehmet Budakçı ◽  
Süleyman Şenol ◽  
Mustafa Korkmaz
Keyword(s):  
Compression Ratio ◽  
Tangential Direction ◽  
Populus Nigra ◽  
Low Density ◽  
Poplar Wood ◽  
Application Time ◽  
Black Poplar ◽  
Different Temperatures ◽  
Tangential Directions ◽  
Control Samples

The radial and tangential swelling as well as the fully dried density of low-density wood materials densified via the Thermo-Vibro-Mechanic® method were evaluated in response to applying wood stain and preservative. The samples obtained from Uludağ fir (Abies bornmüelleriana Mattf.) and black poplar (Populus nigra L.) in the radial and tangential direction were pre-treated with wood stain and preservative before undergoing Thermo-Vibro-Mechanic® densification. Thermo-Vibro-Mechanic® densification was performed at three different temperatures (100 °C ± 3 °C, 120 °C ± 3 °C, and 140 °C ± 3 °C), three different vibration pressures (0.60 MPa, 1.00 MPa, and 1.40 MPa), and three different vibration times (20 s, 60 s, and 100 s). Afterwards, changes in the fully dried density and swelling amounts in the radial and tangential directions of the samples were determined. The fully dried density increased by 15.4% to 38% and the radial and tangential swelling amounts increased by 73.2% to 242.6%, when the densified samples were compared to the control samples. In general, the fully dried density and swelling values increased depending on the Thermo-Vibro-Mechanic® densification parameters; higher values were found as the compression ratio and total application time increased.

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.

Study on Properties of Modified Poplar Wood

2014 ◽  
Vol 926-930 ◽  
pp. 242-245
Author(s):  
Yong Wang ◽  
Ze Jun Chen ◽  
La Yun Deng ◽  
You Hua Fan
Keyword(s):  
Mechanical Properties ◽  
Comparative Study ◽  
Water Absorption ◽  
Dimensional Stability ◽  
Physical And Mechanical Properties ◽  
Dry Density ◽  
Poplar Wood ◽  
Absorption Ratio ◽  
Different Levels ◽  
Modified Wood

The paper based on a comparative study between poplar wood and modified poplar wood, concerning dimensional stability, physical and mechanical properties. The result showed that air-dry density and ASE value of modified wood samples were increasing in different levels with change of the modifier concentration, compared with untreated poplar wood. The air-dry density of modified wood reached 0.41 g/cm3 with increase of 5.3% compared to poplar wood. ASE reached 47.8% and the water-absorption ratio decreased by 38% at most when the modifier concentration was 30 wt.%. Moreover, the MOE and MOR of modified poplar wood increased up to 27.4% and 13% respectively when the modifier concentration was 25 wt.%. The SEM spectrum showed some wood rays and the gaps between staggered fibers were filled by modifier.

scholarly journals Effects of temperature and time of thermal modification on density and colour of Pinus insularis and Dacrycarpus imbricatus wood

2020 ◽  
Vol 19 (05) ◽  
pp. 35-45
Author(s):  
Hoa V. Hoang
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Thermal Modification ◽  
Dry Density ◽  
Southeast Region ◽  
Pinus Kesiya ◽  
Modification Process ◽  
Effects Of Temperature ◽  
Control Samples ◽  
Modified Wood

The Pinus kesiya and Podocarp (Dacrycarpus imbricatus) woods were obtained from the plantations of the Southeast region of Vietnam, with the initial humidity of 80 - 85%. The wood was cut into boards with dimensions of 40 x 80 mm to 120 x 500 mm. In this study, the Pinus kesiya and Podocarp woods were thermally treated at with high temperatures ranging from 161oC to 218oC and the duration from 7.5 h to 13 h. The experiment results showed that the oven-dry density of pine and Bach tung tended to decrease when it was treated at high temperatures during long periods of time. In particular, the density of Pinus kesiya and Podocarp woods decreased about 3.17 - 17.3% and 3.45 - 20.73%, respectively, compared with the control samples. In the thermal modification process, under the effects of high temperature Pinus kesiya and Podocarp woods became darker than the modified wood

Research of Wood Thermal Modification Process in Flue Gases Environment

2017 ◽  
Vol 265 ◽  
pp. 266-271
Author(s):  
Ruslan R. Safin ◽  
P.A. Kaynov ◽  
Elena A. Beliakova
Keyword(s):  
Flue Gas ◽  
Consumption Rate ◽  
Thermal Modification ◽  
Flue Gases ◽  
Wood Processing ◽  
Modification Process ◽  
Urgent Task ◽  
Modes Of Processing ◽  
Energy Consumption Rate ◽  
Modified Wood

Thermal modification is a modern demanded technology allowing receiving natural environmentally friendly material with increased bioproofness and dimensional stability. However, the known technologies of heat treatment of massive wood are rather power-intensive therefore an urgent task is to decrease the energy consumption rate of this process. For this purpose the authors have suggested the technology at which the flue gases, received by gasification of waste of the wood processing industry, act as the agent of processing. The results of the research of this process are presented in the article, the rational modes of processing for concrete types of timber (oak, pine and birch, thickness from 30 to 60 mm) are defined and also the interrelation between the moist characteristics of the wood fuel used for receiving flue gas and the technological modes of processing of massive wood are established. It is also defined that the thickness and breed of material, namely the maintenance of pentosanes as a part of the modified wood exerts impact on the process of thermal decomposition of timber.

Effect of initial moisture content on the anti-swelling efficiency of thermally modified Scots pine sapwood treated in a high-pressure reactor under saturated steam

Holzforschung ◽  
2014 ◽  
Vol 68 (3) ◽  
pp. 323-326 ◽  
Author(s):  
Lauri Rautkari ◽  
Callum A.S. Hill
Keyword(s):  
High Pressure ◽  
Relative Humidity ◽  
Moisture Content ◽  
Mass Loss ◽  
Scots Pine ◽  
Initial Moisture Content ◽  
Thermal Modification ◽  
Saturated Steam ◽  
Modification Process ◽  
Modified Wood

Abstract The effects of initial moisture content (MC) on anti-swelling efficiency (ASE), mass loss (ML), and equilibrium MC (EMC) at 65% relative humidity of thermally modified Scots pine sapwood under saturated steam (TMSA) has been investigated. ML during the TMSA process was higher with the specimens containing moisture before modification compared with initially dry specimens. Surprisingly, the EMC of the modified specimens with initial moisture was higher than that observed with the modified wood that was initially dry before the modification process. Higher initial MC before thermal modification results in a lower ASE.

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