Comparison of dynamic sorption and hygroexpansion of wood by different cyclic hygrothermal changing effects II

2017 ◽  
Vol 41 (4) ◽  
pp. 360-376 ◽  
Author(s):  
Tiantian Yang ◽  
Jiamin Wang ◽  
Nan Sheng ◽  
Erni Ma
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Average Rate ◽  
Dimensional Change ◽  
Dimensional Changes ◽  
Wood Processing ◽  
Content Change ◽  
Period 2 ◽  
Two Factors ◽  
Temperature Constant

Dynamic wood sorption and hygroexpansion by different cyclic hygrothermal changing effects were investigated. Poplar ( populus euramericana Cv.) specimens, 20 mm in radial (R) and tangential (T) directions with two thicknesses of 4 and 10 mm along the grain, were subjected to three rounds under control of these two factors. In the first round, relative humidity changed sinusoidally between 75% and 45% with temperature constant at 20°C. In the second round, temperature changed sinusoidally between 5°C and 35°C with relative humidity constant at 60%. In the third round, relative humidity changed sinusoidally between 75% and 45%, simultaneously temperature changed between 5°C and 35°C. In each round, three sinusoidal change cyclic periods were operated: 1, 6, and 24 h. The measurement of moisture and dimensional responses showed the following results: (1) moisture and dimensional changes were both presented generally in sinusoidal mode. Their amplitudes were lower for thicker specimens exposed to shorter cyclic period. (2) Comparing with the effect brought by changing a single parameter, that is, changing relative humidity or temperature alone, changing relative humidity and temperature together brought greater impact on the specimens. Under a typical air-dry condition at 20°C and 60% relative humidity, this comparison was more obvious, especially for dimensional changes. (3) When the amplitudes resulted in changing relative humidity and changing temperature were superposed, its value was higher than which brought by changing relative humidity and temperature together with the maximum ratio of 1.48. (4) Moisture-content change (ΔMC) and variation of T-dimensional change (ΔT) were all linearly correlated with treating time. Less time was needed to reach a given ΔMC or ΔT, namely, larger ΔMC or ΔT could be attained within the same time by changing relative humidity and temperature together, where the greatest average rate of wood sorption and hygroexpansion could be observed. All these results indicated that in practice, sinusoidally controlling the changes in relative humidity and temperature together was most efficient to adjust the moisture content and deformation in wood processing and application.

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.

Dynamic moisture sorption and hygroexpansion of Populus euramericana Cv. under two cyclic hygrothermal conditions

Holzforschung ◽  
2016 ◽  
Vol 70 (12) ◽  
pp. 1191-1199 ◽  
Author(s):  
Tiantian Yang ◽  
Erni Ma ◽  
Jianhui Zhang
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Environmental Conditions ◽  
Moisture Sorption ◽  
Longitudinal Direction ◽  
Measured Data ◽  
Populus Euramericana ◽  
Dimensional Changes ◽  
Unit Change ◽  
Condition B

Abstract Poplar (Populus euramericana Cv.) specimens, 20 mm in radial (r) and tangential (t) directions with thicknesses of 4 mm and 10 mm along the longitudinal direction, were subjected to cyclic environmental conditions, in the course of which the relative humidity (RH) changed sinusoidally between 75% and 45% at 20°C (condition A), or the temperature (T) was changed sinusoidally within 5–35°C at 60% RH (condition B). Moisture content (MC), as well as the t- and r-dimensional changes were measured as a response to the dynamic environmental conditions. The measured data also changed sinusoidally but they lagged behind the triggering original RH or T data. This effect was much higher under condition A than under condition B. The observed equivalent RH and T changes at different ΔMCs or Δts served for comparison of the responses to RH and T, and the former were less pronounced than the latter. MC and t-dimensional changes per unit change of RH were greater than those per unit change of T but still lower than static values. In summary, the effects of dynamic RH change are larger than those of T, especially concerning MC responses compared to dimensional changes.

Experimental Study on Gravel Soils of Matrix Suction

2013 ◽  
Vol 275-277 ◽  
pp. 310-315 ◽  
Author(s):  
Hong Mei Tang ◽  
Pei Wei Liao ◽  
Lin Feng Wang ◽  
Hong Kai Chen
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Curved Surface ◽  
Soil Water Characteristic Curve ◽  
Content Change ◽  
Two Factors ◽  
The Matrix ◽  
Matrix Suction

Soil-water characteristic curve（SWCC）is closely relevant to two main factors which are structure and moisture content. According to the two factors the values of matrix suction of 45 groups experimental specimens within different moisture content and soil -stone ratio of unsaturated soil are get through filter paper method. Date analysis shows that relation between matrix suction and soil-stone ratio at different moisture states is of different characteristics. Relation between matrix suction and water content is notably nonlinear. Distribution of matrix suction is curved surface in the moisture and soil-stone ration state space which is the function of water content and soil-stone ratio, in which the axial plan is parallel to the axis of soil-stone ratio.At low water content,the matrix suction on the moisture content change is very sensitive, at high moisture content and closed to saturation stage matrix suction hardly changes along with water content and soil-stone ratio change. The curved surface which Located in the middle section ,the matrix suction on the change of water content are more sensitive, reduced with water content increasing; and in this phase the matrix suction is insensitive to the variation of soil-stone ratio. Finally, it is concluded that the saturation to describe the soil water characteristic curve is a bad choice, with moisture to depict the so. In contrast, directly using the water content to describe the soil water characteristic curve is better.

Effect of Thermal Modification on the Physical Properties of Populus ussuriensis

2012 ◽  
Vol 476-478 ◽  
pp. 1889-1892
Author(s):  
Dong Xing ◽  
Min Xu ◽  
Jiang Tao Shi ◽  
Jian Li
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Treatment Process ◽  
Drying Shrinkage ◽  
Dimensional Change ◽  
Thermal Modification ◽  
Heat Treatment Process ◽  
Content Change ◽  
Populus Ussuriensis ◽  
Moisture Content Change

Heat treatment is an environmental method of wood modification. The density of Populus ussuriensis, dimensional change and equilibrium moisture content change were tested through the different temperature processing, and get the influence of heat treatment process on the performance of the wood. The results show that heat treatment is an effective way to improve wood dimensional stability and shrinkage properties. With the improvement of heat treatment intensity, the equilibrium balance moisture content of wood will then gradually reduced. When treating temperature reaches 180°C above, the wood drying shrinkage properties greatly decreased, and trend to stable.

scholarly journals Determination of Swelling and Dimensional Stability of Some Nigerian Timber Species

2020 ◽  
pp. 24-29
Author(s):  
G. C. Ajuziogu ◽  
A. N. Amujiri ◽  
E. U. Njoku ◽  
C. B. Ozokolie ◽  
E. O. Ojua
Keyword(s):  
Moisture Content ◽  
Dimensional Change ◽  
Timber Species ◽  
Strong Positive Correlation ◽  
Content Change ◽  
Radial Dimension ◽  
Dimension Stability ◽  
Swelling Coefficient ◽  
Timber Market ◽  
Daniellia Oliveri

Aim: The absorption of moisture and dimensional distortion are the major shortcomings of wood utilization as building and furniture materials. This study was aimed at determining the moisture content, swelling ability and dimension stability of five selected timber species. Methods: The samples were collected with the help of the Forest Ranger from the Forestry Department of Enugu State, Nigeria, attached to the Nsukka timber market. The wood samples were evaluated for moisture content change, shrinkage or swelling (%) coefficient, amount of swelling and dimensional change. Results: The change in moisture content across the five species was in the order of Gmelina aborea < Milicia excels < Daniellia oliveri < Alstonia bonnie < Antiaris toxicaria. At 12hrs, Gmelina aborea recorded significantly (P < 0.05) the highest dimension change (46 ± 0.70%) in the radial dimension (direction) as compared to the other species except for Antiaris toxicaria. The swelling coefficient and the amount of swelling were observed to have a strong positive correlation with the dimensional change in the sampled wood. Conclusion: The lower swelling coefficient and the amount of swelling observed in Milicia excels among the five timber species, make it a more suitable species for industrial use.

CATFISH DRYING (Clarias Batraclus) USING ‘TEKO BERSAYAP’ SOLAR DRYER

2012 ◽  
Vol 2 (1) ◽  
pp. 14-20
Author(s):  
Yuwana Yuwana
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Ambient Temperature ◽  
Drying Rate ◽  
Drying Process ◽  
Drying Time ◽  
Ambient Relative Humidity ◽  
Solar Dryer

Experiment on catfish drying employing ‘Teko Bersayap’ solar dryer was conducted. The result of the experiment indicated that the dryer was able to increase ambient temperature up to 44% and decrease ambient relative humidity up to 103%. Fish drying process followed equations : KAu = 74,94 e-0,03t for unsplitted fish and KAb = 79,25 e-0,09t for splitted fish, where KAu = moisture content of unsplitted fish (%), KAb = moisture content of splitted fish (%), t = drying time. Drying of unsplitted fish finished in 43.995 hours while drying of split fish completed in 15.29 hours. Splitting the fish increased 2,877 times drying rate.

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