scholarly journals Dimensional Stability, Thermal Degradation and Termite Resistant Studies of Chemically Treated Wood

2010 ◽  
Vol 2 (2) ◽  
Author(s):  
Juthika Sonowal ◽  
P. K. Gogoi
Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1114
Author(s):  
Bruno Esteves ◽  
Helena Ferreira ◽  
Hélder Viana ◽  
José Ferreira ◽  
Idalina Domingos ◽  
...  

The introduction of new species in forest management must be undertaken with a degree of care, to help prevent the spread of invasive species. However, new species with higher profitability are needed to increase forest products value and the resilience of rural populations. Paulownia tomentosa has an extremely fast growth. The objective and novelty of this work was to study the potential use of young Paulownia trees grown in Portugal by using heat treatment to improve its properties, thereby allowing higher value applications of the wood. The average chemical composition of untreated and heat-treated wood was determined. The extractive content was determined by successive Soxhlet extraction with dichloromethane (DCM), ethanol and water as solvents. The composition of lipophilic extracts was performed by injection in GC-MS with mass detection. Insoluble and soluble lignin, holocellulose and α-cellulose were also determined. Physical (density and water absorption and dimensional stability) and mechanical properties (bending strength and bending stiffness) and termite resistance was also determined. Results showed that extractive content increased in all solvents, lignin and α-cellulose also increased and hemicelluloses decreased. Compounds derived from the thermal degradation of lignin were found in heat-treated wood extractions. Dimensional stability improved but there was a decrease in mechanical properties. Resistance against termites was better for untreated wood than for heat-treated wood, possibly due to the thermal degradation of some toxic extractives.


Holzforschung ◽  
2018 ◽  
Vol 72 (4) ◽  
pp. 291-299 ◽  
Author(s):  
Clément L’Hostis ◽  
Marie-France Thévenon ◽  
Emmanuel Fredon ◽  
Philippe Gérardin

AbstractBeech wood has been treated by impregnation followed by heating at various temperatures with solutions containing citric acid (CA) or tartaric acid (TA) alone or in combination with glycerol (G), i.e. with G+CA and G+TA. The resulting modified woods were tested in terms of resistance to leaching, durability and dimensional stability. These properties are improved as a function of heating temperature, which leads to higher levels of poly-esterification involving grafting onto wood simultaneously with thermal degradation of wood. Dimensional stability of all treated wood was increased, but glycerol does not have a positive effect with this regard. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy contributed to understanding the effects of the different treatments.In situpolymerization of G+TA at 140°C increased the bending resistance, while G+CA polymerization does not compensate notably the mechanical weakness induced by thermal degradation of wood at higher temperatures. However, G+CA treatment is more efficient regarding leaching and decay resistance, than that with G+TA.


Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 881
Author(s):  
Mihaela Liu ◽  
Guanglin Xu ◽  
Jianan Wang ◽  
Xinwei Tu ◽  
Xinyou Liu ◽  
...  

Dimensional stability proves to be an important factor affecting the quality of wooden products. As a sort of crude and thermoplastic resin, shellac excreted by lac insects demonstrates water-repellent and environmental-friendly features. The research impregnated shellac with wood at room temperature and with a vacuum-pressure procedure. Efforts were made to examine how shellac treatment affected the dimensional stability, moisture absorption, chemical structure, thermostability, as well as morphological characteristics of wood. Results indicated that shellac treatment was a type of efficient solution useful in the enhancement of the dimensional stability of wood. Shellac solution had good permeability in the wood, and the weight percentage gain reached 13.01% after impregnation. The swelling coefficients of treated wood in the tangential and radial directions decreased by 20.13% and 24.12%, respectively, indicating that impregnation could improve wood dimensional stability. The moisture absorption of shellac-treated wood was reduced by 38.15% under 20 °C and 65% relative humidity. Moreover, shellac treatment significantly modified wood structure, although there were no drastic changes in the spectra. Specimens for shellac treatment ran across two decomposition peaks at 350 and 390 °C, and specimens in the control group saw one more common derivative thermogravimetric curve when the sharp peak approached 355 °C. After impregnation of shellac into wood, the shellac blocked pits and hardened on the intrinsic layer of the wood for fear of hygroscopicity. The practice was applicable to a variety of wood products, such as buildings, furniture, and landscape architecture.


2009 ◽  
Vol 79-82 ◽  
pp. 1021-1024 ◽  
Author(s):  
Yong Feng Li ◽  
Yi Xing Liu ◽  
Xiang Ming Wang ◽  
Xiu Rong Li

In order to improve the durability of marine wood against the long-term marine corrosion, the study explores to use two bifunctional reagents, maleic anhydride (Man) and glycidyl methacrylate(GMA), to react with wood by impregnating them into the porous structure of wood and further initiating them to polymerize with an initiator, AIBN, through a heat process. After the above modification, the durability of the marine wood treated with polymer was tested, and its mechanism was further analyzed as well. The testing results of the durability show that the acid resistance, the alkali resistance, the decay resistance against marine borers and the dimensional stability of the treated wood increases by 2.02 times, 12.39 times, 4.96 times and 3 times over untreated wood, respectively; and its Anti Swelling Efficiency (ASE) for dimensional stability reaches 53%, which almost equals the value of the wood treated by PEG-1500 under the same condition, while its leachability resistance is greatly higher than wood treated by PEG-1500. The analysis result with FTIR indicates that Man and GMA both react with wood, and Man reacts with the hydroxyl group of wood cell walls by its anhydride group, and GMA polymerizes in the porous structure of wood. The charactering result with SEM reveals that the resultant polymer fills in wood cell lumina as a solid form, which contacts tightly the wood cell walls without obvious gaps. The greatly reducing amount of hydroxyl groups after the reaction and the heavy jamming channels for water and marine borers approaching to wood cell walls both contribute to the improving durability of the modified wood.


Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 86 ◽  
Author(s):  
Jun Jiang ◽  
Yupeng Chen ◽  
Jinzhen Cao ◽  
Changtong Mei

Wood treatment was conducted by paraffin/acrylate compound emulsion. Response surface methodology (RSM) was applied for modeling and to determine the relationship between hydrophobicity and influencing factors. The results showed that the paraffin emulsion concentration and acrylate emulsion percentage had significant influences on water absorption (WA) and mass percentage gain (MG). The WA decreased obviously with increasing acrylate emulsion percentage. The correlation models for WA and MG showed a good prediction due to the straight-line distribution in the normal probability plot of residuals. The optimal conditions (5.57% paraffin emulsion concentration, 20% acrylate emulsion percentage, and 10 min treatment time) provided by RSM were acceptable for predicting the MG and WA. Compared to untreated (66°) and paraffin emulsion treated wood (94°), the wood treated by compound emulsion showed the highest water contact angle (133°) and better dimensional stability. This could be ascribed to a synergistic effect (bulking effect and filling effect) provided by paraffin and acrylate, which could form a completely hydrophobic film in wood.


Author(s):  
Lijie Qu ◽  
Zhenyu Wang ◽  
Jing Qian ◽  
Zhengbin He ◽  
Songlin Yi

Abstract Acidic aluminum sulfate hydrolysis solutions can be used to catalyze the thermal degradation of wood in a mild temperature environment, and thus reduce the temperature required for heat treatment process. To improve the dimensional and thermal stability of Chinese fir during heat treatment at 120 °C, 140 °C and 160 °C, this study investigated the effects of soaking pretreatment with 5%, 10% and 15% aluminum sulfate on the chemical and structural changes of the heat-treated Chinese fir. The results indicated that the samples treated at 15% aluminum sulfate concentration and 160 °C heat treatment achieved the best dimensional and thermal stability. Chemical analyses by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) indicated that the catalysis of aluminum sulfate resulted in degradation of hemicelluloses during the heat treatment, and an increase in the soaking concentration and heat treatment temperature also affected the thermal degradation of celluloses. The scanning electron microscope (SEM) and mass changes test results proved that the hydrolyzed aluminum flocs mainly adhered to the inner wall of the wood tracheid as spherical precipitates, and when the soaking concentration reached 10% and 15%, a uniform soaking effect could be achieved. The thermogravimetric (TG) analysis revealed the soaking pretreatment effectively improved the thermal stability of the heat-treated wood by physically wrapping and promoting the formation of a carbon layer on the wood surface during heat treatment. Thus, aluminum sulfate soaking pretreatment exerted a great effect on the dimensional and thermal stability of wood, allowing heat treatment to be performed at a lower temperature.


2014 ◽  
Vol 1001 ◽  
pp. 373-378
Author(s):  
Eva Ružinská ◽  
Iveta Mitterová ◽  
Martin Zachar

The paper deals with the issues relating to the assessment of the possible behaviour of the surface treated wood prepared by application solvent based polyurethane coatings in realistic conditions of use it is important to assess the characteristics of thermal degradation of these materials in simulations of reaction (ignition test) to fire and add the other necessary criteria, allowing an overall assessment of fire-technical (due to valid standards from the point of the reaction to fire) and ecological characteristics.


2011 ◽  
Vol 341-342 ◽  
pp. 80-84 ◽  
Author(s):  
Yu Bo Chai ◽  
Jun Liang Liu ◽  
Xing Zhen

In order to improve the dimensional stability, mechanical properties and fire resistance of the wood from Cryptomeria fortunei, the melamine-urea-formaldehyde (MUF) resin and the mixture of MUF/boric acid/borax (MBB) were prepared and used as the wood modification solution. Results show that both the MUF resin and the MBB solutions exhibit good permeability to wood. Under the same treatment conditions, the weight percent gains (WPG) of treated wood increases with the increasing concentration of modification solutions. MUF and MBB modification solutions can effectively enhance the dimensional stability, MOR, MOE and fire resistance of wood. Compared with MBB treated wood, MUF treated wood exhibits higher MOR and dimensional stability. The MBB treated wood has higher MOE and fire resistance than MUF treated wood.


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