scholarly journals Effect of microwave and steam treatment on the thermo-hygro-plasticity of beech wood

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 8338-8352
Author(s):  
Jakub Dömény ◽  
Martin Brabec ◽  
Radim Rousek ◽  
Lauri Rautkari ◽  
Petr Čermák
Keyword(s):  
Moisture Content ◽  
Structural Changes ◽  
Mechanical Performance ◽  
Beech Wood ◽  
European Beech ◽  
Microwave Treatment ◽  
Steam Treatment ◽  
Saturated Steam ◽  
Similar Degree ◽  
Loading Mode

The effects of microwave and steam treatment were analyzed relative to the immediate (thermo-hygro-plasticity) and post-assessed (permanent changes) properties of wood. The study was conducted using European beech (Fagus sylvatica L.) standard and 1.5 times up-scaled (only for microwave-heated and reference samples) bending specimens tested in a static three-point loading mode. The specimens were plasticized by heat and moisture (1) separately and (2) simultaneously by heating moist specimens using (i) various microwave regimes in continuous mode, and (ii) heated saturated steam in discontinuous mode. Oven-dried specimens tested at 20 °C served as references. The thermo-hygro-plasticity was studied immediately after treatment, whereas the permanent changes were assessed after oven-drying of plasticized specimens to 0% moisture content. Permanent structural changes were analyzed using scanning electron microscopy. Microwave treatment increased the plasticity of wood (decreasing the modulus of elasticity by 70%) comparably to steam treatment, when the output moisture content was 30% or higher. A similar degree of plasticity was found in up-scaled specimens heated by microwaves. Further analyses confirmed that microwave treatment did not cause any permanent damage to wood structure or reduce mechanical performance. The results showed that microwave treatment is an efficient alternative to steaming when plasticizing moist wood.

Multi-Scale Analysis of Changes in Crack-Free Flattened Moso Bamboo After Saturated Steam Treatment and Flattening Process

2021 ◽  
Vol 13 (7) ◽  
pp. 1259-1267
Author(s):  
Tiancheng Yuan ◽  
Xiao Xiao ◽  
Xin-Han ◽  
Yifei Wu ◽  
Xinzhou Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Moisture Content ◽  
Mechanical Analysis ◽  
Moso Bamboo ◽  
Steam Treatment ◽  
Saturated Steam ◽  
Main Peak ◽  
Multi Scale ◽  
Main Chemical Composition ◽  
The Relationship

ABSTRACTIn this study, Moso bamboo was firstly softened by saturated steam and then pressed flat by a machine. The modification effect (high-temperature saturated steam) was characterized by FTIR, XRD, SEM, and wet chemistry. The dynamic mechanical analysis (DMA) was used to investigate the effects of three variables (temperature, time, and moisture content) on the thermal-mechanical properties of Moso bamboo. The results indicated that high-temperature saturated steam can effectively soften bamboo cells under high pressure at high temperature. As expected, in comparison with reference samples, the content of hemicellulose and cellulose decreased, while that of relative lignin increased. The results of the changes in main chemical composition were further confirmed by FTIR, which showed that the intensity of the main peak belongs to hemicellulose decreased, so the polysaccharide such as hemicellulose went through the process of hydrolysis and pyrolysis. An increase in the moisture content of bamboo led to a decrement in storage modulus value, which can be attributed to the plasticizing effect. Both temperature and time had a positive effect on the reduction in glass transition temperature. This conclusion not only helps to understand the relationship between bamboo and water, but also provides guide for the utilization and production process of crack-free flattened bamboo board and its products in the construction and building fields.

Comparison of mechanical properties of thermally modified wood at growth ring and cell wall level by means of instrumented indentation tests

Holzforschung ◽  
2009 ◽  
Vol 63 (4) ◽  
Author(s):  
Stefanie Stanzl-Tschegg ◽  
Wilfried Beikircher ◽  
Dieter Loidl
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Thermal Treatment ◽  
Mechanical Performance ◽  
Growth Ring ◽  
Beech Wood ◽  
Thermal Modification ◽  
Wood Structure ◽  
Instrumented Indentation ◽  
Indentation Tests

Abstract Thermal modification is a well established method to improve the dimensional stability and the durability for outdoor use of wood. Unfortunately, these improvements are usually accompanied with a deterioration of mechanical performance (e.g., reduced strength or higher brittleness). In contrast, our investigations of the hardness properties in the longitudinal direction of beech wood revealed a significant improvement with thermal modification. Furthermore, we applied instrumented indentation tests on different hierarchical levels of wood structure (growth ring and cell wall level) to gain closer insights on the mechanisms of thermal treatment of wood on mechanical properties. This approach provides a variety of mechanical data (e.g., elastic parameters, hardness parameters, and viscoelastic properties) from one single experiment. Investigations on the influence of thermal treatment on the mechanical properties of beech revealed similar trends on the growth ring as well as the on the cell wall level of the wood structure.

Structural Changes on Charring Woods of Dichrostachys and Salix from Southern Africa: The Effect of Moisture Content

IAWA Journal ◽  
1986 ◽  
Vol 7 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Juliet Prior ◽  
K. L. Alvin
Keyword(s):  
Moisture Content ◽  
Southern Africa ◽  
Structural Changes ◽  
Initial Increase ◽  
Dichrostachys Cinerea ◽  
Chemical Changes ◽  
Structural Alterations ◽  
Wood Pyrolysis ◽  
Effect Of Moisture ◽  
Physical And Chemical

Air-dried and saturated cubes of fully developed wood of Dichrostachys cinerea (Leguminosae) and Salix subserrata (Salicaceae) were charred for 60 minutes at 400°C. An initial increase in moisture content caused few structural alterations in Salix but in Dichrostachys it resulted in considerable ray distension and massive deformation of non-gelatinous fibres. An attempt is made to correlate these observations with the physical and chemical changes known to occur during wood pyrolysis.

scholarly journals Effect of Saturated Steam Heat Treatment on Physical and Chemical Properties of Bamboo

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1999 ◽  
Author(s):  
Qiuyi Wang ◽  
Xinwu Wu ◽  
Chenglong Yuan ◽  
Zhichao Lou ◽  
Yanjun Li
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Treatment Time ◽  
Flexural Modulus ◽  
Initial Moisture Content ◽  
Chemical Properties ◽  
Saturated Steam ◽  
Xrd Patterns ◽  
Physical And Chemical ◽  
Steam Heat

The aim of this study was to investigate the effects of the heat treatment time and initial moisture content of bamboo on the corresponding chemical composition, crystallinity, and mechanical properties after saturated steam heat treatment at 180 °C. The mechanism of saturated steam heat treatment of bamboo was revealed on the micro-level, providing a theoretical basis for the regulation of bamboo properties and the optimization of heat treatment process parameters. XRD patterns of the treated bamboo slices were basically the same. With the increase in the initial moisture content of bamboo, the crystallinity of bamboo increased first and then decreased after treatment. Due to the saturated steam heat treatment, the content of cellulose and lignin in bamboo slices increased while the content of hemicellulose decreased, but the content of cellulose in bamboo with a 40% initial moisture content increased first and then decreased. The shear strength of treated bamboo changed little within 10 min after saturated steam heat treatment, and then decreased rapidly. During the first 20 min with saturated steam heat treatment, the compressive strength, flexural strength, and flexural modulus of elasticity of the treated bamboo increased, and then decreased.

scholarly journals Simulations and Experiments of the Soil Temperature Distribution after 2.45-GHz Short-Time Term Microwave Treatment

Agriculture ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 933
Author(s):  
Xiaohe Sun ◽  
Changyuan Zhai ◽  
Shuo Yang ◽  
Haolin Ma ◽  
Chunjiang Zhao
Keyword(s):  
Soil Moisture ◽  
Field Strength ◽  
Moisture Content ◽  
Soil Temperature ◽  
Output Power ◽  
Soil Moisture Content ◽  
Microwave Treatment ◽  
Soil Treatment ◽  
Internal Temperature ◽  
Soil Disinfection

Microwave treatment is a green and pollution-free soil disinfection method. The application of microwaves to disinfect soil before cultivation is highly important to increase crop yields and protect the ecological environment. The electromagnetic field is an important parameter influencing the soil temperature field in the process of microwave soil treatment, and the change in soil temperature directly affects soil disinfection. Therefore, this article carried out research on the heating pattern in North China loess due to microwave treatment. First, COMSOL software was employed to simulate the microwave soil treatment process to analyze microwave penetration into soil. Second, with the application of microwaves at the designed frequency produced with a 2.45-GHz tunable microwave generating microdevice, soil with water contents of 0%, 10%, 20%, and 30% was treated for 10~60 s (at 10-s time intervals), and experiments on the influence of the microwave output power, treatment time, and soil moisture content on the soil temperature were performed via the controlled variable method. The simulation results indicate that with increasing soil moisture content, the microwave frequency inside the soil model increases, and the electric field intensity value decreases in the model at the same depth. After microwaves traverse through the 20-cm soil model, the incident field strength is three orders of magnitude lower than the outgoing field strength. The results of the microwave soil treatment experiment reveal that: (1) Compared to microwave output power levels of 1.8 and 1.6 kW, a level of 2 kW is more suitable for microwave soil disinfection. (2) After treatment, the highest temperature occurs on the soil surface, not within the soil. (3) The location of the highest soil internal temperature after microwave treatment increasingly approaches the soil surface with increasing soil moisture content, and the microwave output power does not affect the location of the highest soil internal temperature. Combining the electromagnetic field simulation and microwave soil treatment experiment results, it was found that the higher the field strength is, the higher the temperature value, and the highest soil internal temperature after microwave treatment often occurs at the first electromagnetic wave peak.

Effect of pretreatments and temperature on rehydration kinetics of naga chili (Capsicum chinense)

Food Research ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 38-46
Author(s):  
M.R. Rana ◽  
K.N. Sakib ◽  
M.Z. Islam ◽  
P.C. Das ◽  
R. Ara
Keyword(s):  
Moisture Content ◽  
Ethyl Oleate ◽  
Cost Effective ◽  
Microwave Treatment ◽  
Capsicum Chinense ◽  
Nutrient Quality ◽  
Zero Order Kinetics ◽  
Cost Effective Approach ◽  
C 50 ◽  
Drying Conditions

Naga chili (Capsicum chinense) is rich in capsaicin content that provides a distinctive aroma and strong pungency. Drying with pretreatment is regarded as a cost-effective approach to retain better nutrient quality, whereas rehydration properties consider a quality index to optimize the drying conditions. This study aimed to determine rehydration kinetics and rehydration characteristics of pretreated hot-air dried Naga chili. The pretreatment was consisting of water blanching (90°C for 5 mins), steam blanching (100° C for 1 min), microwave treatment (650 W for 100 s), and dipping into sugar 70°Bx, 0.5% citric acid, 2% ethyl oleate + 3% potassium carbonate, and 2% potassium meta bi-sulfite solution. After drying at 60°C, the rehydration was done at 25°C, 50°C, and 75°C, respectively. The rehydration kinetics were evaluated by fitting the experimental data into empirical kinetic models: Peleg's model, 2nd order, 1st order, and Zero-order kinetics. Among these models, the rehydration behavior was best described by Peleg's model, where the highest R2 (0.9964), lowest χ 2 (0.0001) and RMSE (0.0064) values were obtained. Different rehydration characteristics such as moisture content, equilibrium moisture content, rehydration ratios were also determined. The highest moisture content (8.10 g moisture/g dry sample) was found at higher rehydration temperature (75°C), whereas the lowest moisture content ranges were recorded at 25°C. After moisture contents got equilibrium, the rehydrated samples gain weight to 100.15% at 75°C in comparison to the untreated samples. The rehydration ratios were also getting higher with increasing rehydration temperatures.

scholarly journals The Impact of Paraffin-Thermal Modification of Beech Wood on Its Biological, Physical and Mechanical Properties

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1102 ◽  
Author(s):  
Ladislav Reinprecht ◽  
Miroslav Repák
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Beech Wood ◽  
Physical And Mechanical Properties ◽  
Brown Rot ◽  
European Beech ◽  
White Rot ◽  
White Rot Fungus ◽  
Poria Placenta ◽  
The Impact

The European beech (Fagus sylvatica L.) wood was thermally modified in the presence of paraffin at the temperatures of 190 or 210 °C for 1, 2, 3 or 4 h. A significant increase in its resistance to the brown-rot fungus Poria placenta (by 71.4%–98.4%) and the white-rot fungus Trametes versicolor (by 50.1%–99.5%) was observed as a result of all modification modes. However, an increase in the resistance of beech wood surfaces to the mold Aspergillus niger was achieved only under more severe modification regimes taking 4 h at 190 or 210 °C. Water resistance of paraffin-thermally modified beech wood improved—soaking reduced by 30.2%–35.8% and volume swelling by 26.8%–62.9% after 336 h of exposure in water. On the contrary, its mechanical properties worsened—impact bending strength decreased by 17.8%–48.3% and Brinell hardness by 2.4%–63.9%.

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