scholarly journals Moisture-Dependent Strength Properties of Thermally-Modified Fraxinus excelsior Wood in Compression

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1647 ◽  
Author(s):  
Edward Roszyk ◽  
Elżbieta Stachowska ◽  
Jerzy Majka ◽  
Przemysław Mania ◽  
Magdalena Broda
Keyword(s):  
Moisture Content ◽  
Strength Properties ◽  
Treatment Temperature ◽  
Thermal Modification ◽  
Fraxinus Excelsior ◽  
Mechanical Parameters ◽  
Saturation Point ◽  
Wood Moisture ◽  
Intrinsic Anisotropy ◽  
European Ash

European ash (Fraxinus excelsior L.) is one of the species commonly used for wood thermal modification that improves its performance. The presented research aimed to investigate a moisture-dependent strength anisotropy of thermally-modified European ash in compression. Wood samples were modified at 180 °C and 200 °C. Their mechanical parameters were determined in the principal anatomical directions under dry (moisture content of 3%) and wet (moisture content above fibre saturation point) conditions. Effect of heat treatment temperature and moisture content on the ash wood mechanical parameters concerning each anatomical direction were determined. The results show that thermal treatment kept the intrinsic anisotropy of wood mechanical properties. It decreased wood hygroscopicity, which resulted in improved strength and elasticity measured for wet wood when compared to untreated and treated samples. Higher treatment temperature (200 °C) increased wood elasticity in compression in all the anatomical directions despite wood moisture content during the measurements. Multivariate analysis revealed that the modification temperature significantly affected the modulus of elasticity perpendicular to the grain, while in the case of compression strength, the statistically significant effect was observed only parallel to the grain. The results obtained can be useful from an industrial perspective and can serve as part of a database for further modelling purposes.

scholarly journals Quality Control of Thermally Modified Timber Using Dynamic Vapor Sorption (DVS) Analysis

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 666
Author(s):  
Miha Humar ◽  
Rožle Repič ◽  
Davor Kržišnik ◽  
Boštjan Lesar ◽  
Romana Cerc Korošec ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Quality Control ◽  
Moisture Content ◽  
Mass Loss ◽  
Thermal Modification ◽  
Wood Moisture Content ◽  
Vapor Sorption ◽  
Dynamic Vapor Sorption ◽  
Wood Moisture ◽  
Factor C

The importance of thermal modification is increasing worldwide. Increased use of thermally modified timber (TMT) has resulted in a need for reliable quality control, comprising control of variation of the production within defined limits, allowing third-party control in the case of certification and the regulation of customer complaints and claims. Techniques are thus needed to characterise the modification of quality in terms of improved target properties of TMT during industrial production, and of TMT products that have been in service for an arbitrary time. In this study, we aimed to utilise dynamic vapor sorption (DVS) for this purpose. Norway spruce (Picea abies) and European beech (Fagus sylvatica) samples were thermally modified at different temperatures according to different heat treatment techniques: (1) the Silvapro process based on an initial vacuum; (2) an air heat treatment, whereby samples were wrapped in aluminium foil; (3) thermal modification of wood samples in the ambient atmosphere in a laboratory oven. Wood samples from closed processes were analysed for validation. TMT was characterised with respect to mass loss, colour and density. Mass loss of wood due to modification (MLTM) was correlated with factors derived from DVS analysis. The present DVS measurements suggest that the equilibrium wood moisture content (EMC95% RH), the time to reach 10% wood moisture content (t10% MC), and the elongation factor, c, derived from a logarithmic function, can serve as alternative parameters to characterise the quality of several thermal modification processes. Further studies are recommended using other wood species, different modification processes and further parameters gained from DVS measurements to understand the robustness and the predictive power of the applied technique.

Examination of moisture content variation within an operational wet deck

TAPPI Journal ◽  
2013 ◽  
Vol 12 (1) ◽  
pp. 45-50 ◽  
Author(s):  
LAURENCE SCHIMLECK ◽  
KIM LOVE-MYERS ◽  
JOE SANDERS ◽  
HEATH RAYBON ◽  
RICHARD DANIELS ◽  
...  
Keyword(s):  
Moisture Content ◽  
Southeastern United States ◽  
Forest Products ◽  
Time Domain Reflectometry ◽  
Water Application ◽  
Wood Moisture ◽  
International Paper ◽  
Content Variation ◽  
Moisture Variation

Many forest products companies in the southeastern United States store large volumes of roundwood under wet storage. Log quality depends on maintaining a high and constant wood moisture content; however, limited knowledge exists regarding moisture variation within individual logs, and within wet decks as a whole, making it impossible to recommend appropriate water application strategies. To better understand moisture variation within a wet deck, time domain reflectometry (TDR) was used to monitor the moisture variation of 30 southern pine logs over an 11-week period for a wet deck at the International Paper McBean woodyard. Three 125 mm long TDR probes were inserted into each log (before the deck was built) at 3, 4.5, and 7.5 m from the butt. The position of each log within the stack was also recorded. Mixed-effects analysis of variance (ANOVA) was used to examine moisture variation over the study period. Moisture content varied within the log, while position within the stack was generally not significant. The performance of the TDR probes was consistent throughout the study, indicating that they would be suitable for long term (e.g., 12 months) monitoring.

A thermal modification technique combining bulk densification and heat treatment for poplar wood with low moisture content

2021 ◽  
Vol 291 ◽  
pp. 123395
Author(s):  
Xianju Wang ◽  
Dengyun Tu ◽  
Chuanfu Chen ◽  
Qiaofang Zhou ◽  
Huixian Huang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Thermal Modification ◽  
Poplar Wood ◽  
Modification Technique

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.

Temporal change in wood quality attributes in standing dead beetle-killed lodgepole pine

2008 ◽  
Vol 84 (3) ◽  
pp. 392-400
Author(s):  
Steen Magnussen ◽  
Dave Harrison
Keyword(s):  
Moisture Content ◽  
Wood Quality ◽  
Basal Area ◽  
Wood Moisture ◽  
Moisture Regimes ◽  
Standing Dead ◽  
Blue Stain ◽  
Lodgepole Pines ◽  
Ring Analysis ◽  
One Year

The number and size of checks, wood moisture content, extent of blue-stain, rot and decay was examined by stem analysis in 360 mature standing beetle-killed lodgepole pines. Trees came from three areas (Burns Lake, Quesnel, and Vanderhoof) in Central British Columbia. Each area was represented by 14 to 16 sampling areas (stands) distributed evenly across three soil moisture regimes (dry, mesic, wet). Year of death was estimated from tree ring-analysis, local knowledge and insect and disease survey maps. An approximately equal number of trees had been dead for one or two years, three or four years, or for five or more years. During the first five years since death by beetle attack the number of checks per tree increased from 2.5 to 10.2 and the average depth of checks increased from 4.3 cm to 5.1 cm. Checks were deeper, wider, and longer on the drier sites than on mesic and wet sites. Moisture content of sapwood and heartwood was near the fibre saturation point (ca 30%) one year after death and continued to decrease at a rate of approximately 1.7% per year. Both the incidence and the extent (relative to basal area) of rot and decay increased significantly with time since death. All trees had an extensive blue-stain discoloration. Deterioration of wood quality was fastest during the first two years after a beetle attack. Key words: wood checks, moisture content, blue-stain, wood quality, spiral grain, bark beetle

scholarly journals Thermal conductivity and deformation of Taxodium hybrid ‘Zhongshanshan’ during heat transfer process

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2645-2655
Author(s):  
Yuehua Zhu ◽  
Yaoli Zhang ◽  
Biao Pan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Moisture Content ◽  
Transfer Process ◽  
Dimensional Change ◽  
Testing Temperature ◽  
Scientific Basis ◽  
Heat Transfer Process ◽  
Wood Moisture Content ◽  
Wood Moisture

The thermal conductivity and the deformation of wood from the Taxodium hybrid ‘Zhongshanshan’ were studied in the process of heat transfer. The results showed that the average thermal conductivity of this wood was 0.1257 W/(m·K) under the condition of 12% wood moisture content and 30 °C heat transfer temperature. When the testing temperature exceeded 0 °C, the thermal conductivity increased linearly with both temperature and wood moisture content and was affected by the moisture content of the wood. During the heat transfer process, the deformation of features caused repeated swelling and shrinkage in the longitudinal, radial, and tangential directions. The dimensional change was greatly affected by the wood’s moisture content and was less affected by the temperature. These results are of great meaning for the study of the heat transfer process of Taxodium hybrid ‘Zhongshanshan’ wood. Furthermore, it provides a scientific basis for the heat preservation effect, drying treatment, and pyrolysis treatment of Taxodium hybrid ‘Zhongshanshan’ wood for use as a building material.

scholarly journals Microstructure of thermally modified radiata pine wood

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 1523-1533
Author(s):  
José Luis Cabezas-Romero ◽  
Linette Salvo-Sepúlveda ◽  
Helga Contreras-Moraga ◽  
Natalia Pérez-Peña ◽  
Víctor Sepúlveda-Villarroel ◽  
...  
Keyword(s):  
Cell Wall ◽  
Wood Cell Wall ◽  
Morphological Changes ◽  
Untreated Wood ◽  
Radiata Pine ◽  
Treatment Temperature ◽  
Thermal Modification ◽  
Modification Process ◽  
Potential Alternative ◽  
Two Temperatures

The thermal modification of wood is a potential alternative method for improving wood dimensional stability and increasing the resistance of wood to decay. However, during thermal modification, morphological changes occur within the microstructure of the cell, and these confer different properties to the wood. This study investigated the effects of the thermal modification process on the microstructure of radiata pine juvenile wood. Therefore, anatomical measurements were performed via optical microscopy in selected earlywood and latewood samples after each treatment, and the results were compared to untreated wood samples. In this study, two temperatures (190 °C and 210 °C) were considered for the thermal modification process. The results showed that the level of temperature of modification affected to microstructure of cell wall. The cell wall thickness decreased as treatment temperature increased, whereas the average lumen diameter increased slightly as temperature increased. Thermally modified radiata pine showed signs of damage (cracks, broken cells and deformations in the wood cell wall). The proportion of destroyed area increased as temperature increased, and significant differences were evident for the thermal treatment at 210 °C.

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