scholarly journals Delayed elastic strain and set-recovery evaluation in high-pressure densified hybrid poplar wood – New assessment considerations

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 2691-2707
Author(s):  
Kaiya Yan ◽  
Fengming Zhang ◽  
Yang Du ◽  
Hosahalli S. Ramaswamy ◽  
Songming Zhu ◽  
...  
Keyword(s):  
High Pressure ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Elastic Strain ◽  
Hybrid Poplar ◽  
Treated Wood ◽  
Densified Wood ◽  
Poplar Wood ◽  
Recovery Method ◽  
Conventional Methods

The deformation behavior of high-pressure (HP)-treated hybrid poplar wood, the subsequent swelling, and the equilibrium moisture content properties of HP-densified wood were evaluated using a modified delayed strain/set-recovery method of cyclic humidification-dehumidification at different relative humidity (RH) conditions. The HP treatment resulted in significant compression (densification) of the wood under different treatment conditions. For treated wood samples, the value of delayed elastic strain was relatively small when stored at 20 °C and 65% RH, which indicated that HP-densified wood possessed dimensional stability. The HP-compressed poplar yielded lower equilibrium moisture content than the control at low RH, while major increases were observed at high RH above 76%. Marginal of thickness swelling was observed under the cyclic humidification-dehumidification method in the low RH range while significant swelling occurred at high RH. Conventional methods would only show results that were appropriate for storage at high RH environments. The RH threshold for set-recovery of HP-compressed wood was between 33% and 54% for optimal use, and the extent of set-recovery increased rapidly when RH was between 85% and 95%. Such differences could not be recognized with the conventional methods. In addition, the prolonged holding time significantly decreased the RH threshold value (P < 0.05).

scholarly journals Herstellung und Eigenschaften von thermisch vergütetem Holz – eine Übersicht | Production and properties of heat-treated wood: an overview

2005 ◽  
Vol 156 (11) ◽  
pp. 408-410
Author(s):  
Peter Niemz
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Treated Wood ◽  
Wood Industry ◽  
Heat Treated ◽  
New Material

For many years already, the thermic modification of wood has been employed in the wood industry. Numerous new or improved properties such as low equilibrium moisture content and thus lower swelling or improved durability and exotic colour tints characterise this material. Nevertheless, it is certainly open to further improvements, above all with regard to reproducibility and quality guarantees. Regulations for this relatively new material, for which only little experience values exist until now, are to be expected.

Dyeing of Poplar Wood through High-Pressure Processing: Performance Evaluation

2019 ◽  
Vol 62 (5) ◽  
pp. 1163-1171
Author(s):  
Yong Yu ◽  
Kaiya Yan ◽  
Hosahalli S. Ramaswamy ◽  
Songming Zhu ◽  
Huanhuan Li ◽  
...  
Keyword(s):  
High Pressure ◽  
External Surface ◽  
Treated Wood ◽  
Color Difference ◽  
High Pressure Processing ◽  
Poplar Wood ◽  
Dye Uptake ◽  
Surface Color ◽  
Color Dimension ◽  
Dyeing Performance

Abstract. Dyeing of poplar wood through high-pressure (HP) processing was evaluated at different pressure levels (40 to 130 MPa) and compared with conventional hot dip treatment. Dyeing performance was evaluated based on external surface color, fractal color dimension, dye uptake, internal color, elemental composition, and subsequent ultraviolet aging of the wood. The internal microstructure of the treated wood was also examined by scanning electron microscopy (SEM). Results showed that the external surface color difference and change in brightness were significantly greater with HP treatment than with hot dip treatment. The hue angle of HP treated wood surfaces was 1.27 to 4.01 higher and the fractal color dimension was significantly (p &lt; 0.05) lower than that of hot dip treated wood, demonstrating more intense and more uniform distribution of color with HP treatment. The internal color of HP treated wood was also more evenly distributed and more intense, while the hot dip treated wood had no internal dye uptake (zero penetration). SEM analysis showed that the wood structure was damaged by HP treatment, which allowed the dye solution to penetrate into the wood more easily. Among the different pressure levels, the higher pressures resulted in better dyeing performance; however, considering the treatment cost, time, and energy efficiency, 100 MPa treatment may be more economical. Keywords: Color, Dyeing, Fractal dimension, High pressure, Hot dip, Poplar wood.

Plastic and Elastic Strains in Poplar Wood under High-Pressure Densification

2020 ◽  
Vol 63 (6) ◽  
pp. 2021-2028
Author(s):  
Aqiang Li ◽  
Kaiya Yan ◽  
Hosahalli S. Ramaswamy ◽  
Songming Zhu ◽  
Yong Yu
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Plastic Strain ◽  
Wood Density ◽  
Elastic Strain ◽  
Pressure Treatment ◽  
Poplar Wood ◽  
Compressed Wood ◽  
Tangential Directions ◽  
Elastic Strains

HighlightsHigh-pressure densification (HPD) resulted in more than 100% increase in the density of poplar wood.Density of wood during HPD treatment was up to 300% and 100% higher than observed before and after HPD.A method was developed to measure elastic recovery in the radial and tangential directions under HPD.Abstract. Plastic and elastic strains of poplar wood in the radial and tangential directions were investigated after high-pressure densification (HPD) using a special method that detected the elastic strain. There was a large difference in plastic and elastic strains obtained in compressed wood between the radial and tangential directions. The maximum total strain in the radial and tangential directions reached 26.9% and 66.9%, respectively, when compressed at 150 MPa for 300 s. Longer holding time (300 s) increased the plastic strain, by reducing the elastic strain, when the applied pressure was lower than 60 MPa. In addition, a large difference in compressed wood density prevailed when still under pressure as compared with the density measured after the pressure treatment, and both were nearly 1 to 3 times higher than the density of fresh wood. Further, the maximum density observed under pressure was related to the maximum reported density of dry crystalline cellulose plus the entrapped moisture. The mechanical properties of densified wood were also investigated and found to depend on the pressure treatment conditions. Keywords: Elastic strain, High-pressure densification, Mechanical properties, Plastic strain, Wood density.

scholarly journals Colour changes and equilibrium moisture content on thermomechanical densified wood

2021 ◽  
Vol 93 (4) ◽  
Author(s):  
DOUGLAS E. CARVALHO ◽  
MÁRCIO P. DA ROCHA ◽  
RICARDO J. KLITZKE ◽  
PEDRO HENRIQUE G. DE CADEMARTORI
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Densified Wood ◽  
Colour Changes

scholarly journals Comparison of physical-mechanical and mould-proof properties of furfurylated and DMDHEU-modified wood

BioResources ◽  
2019 ◽  
Vol 14 (4) ◽  
pp. 9628-9644
Author(s):  
Wanju Li ◽  
Lifang Chen ◽  
Xingwei Li
Keyword(s):  
Compressive Strength ◽  
Acrylic Acid ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Treated Wood ◽  
Untreated Wood ◽  
Modulus Of Rupture ◽  
Moisture Uptake ◽  
Masson Pine ◽  
Modified Wood

In this study, 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and furfuryl alcohol (FA) modification catalyzed by acrylic acid were comparatively studied. The effects on physical-mechanical properties and durability against mould of Masson pine and Camphor pine wood were investigated, including weight gain rate (WPG), moisture uptake, equilibrium moisture content (EMC), anti-swelling efficiency (ASE), parallel-to-grain compressive strength (CS), modulus of rupture (MOR), and mould resistance. The wood samples modified with DMDHEU closely retained their original color and texture, whereas the color of furfurylated wood became dark brown and the texture became clearer. The WPG of DMDHEU-treated wood ranged from 17.9% to 29.3%, which was lower than that of furfurylated wood that ranged from 36.7% to 39.3%. The equilibrium moisture content of DMDHEU-modified wood was slightly higher than the untreated wood, while furfurylation decreased the EMC of wood by approximately 50% compared with the untreated wood. The dimensional stability, parallel-to-grain compressive strength, and mildew resistance of Masson pine and Camphor pine improved after both modifications noticeably. It was concluded that acrylic acid can be utilized as a catalyst to perform wood furfurylation and DMDHEU modification.

Analysis of the moisture content of maize kernels in over-ripe plants

2006 ◽  
Vol 54 (4) ◽  
pp. 425-430
Author(s):  
T. Árendás ◽  
L. C. Marton ◽  
P. Bónis ◽  
Z. Berzsenyi
Keyword(s):  
Linear Regression ◽  
Moisture Content ◽  
Grain Yield ◽  
Equilibrium Moisture Content ◽  
Weather Conditions ◽  
Positive Correlation ◽  
Maize Grain Yield ◽  
Maize Grain ◽  
Maize Kernels

The effect of varying weather conditions on the moisture content of the maize grain yield was investigated in Martonvásár, Hungary from late August to late September, and from the 3rd third of September to the 1st third of Novemberbetween 1999 and 2002. In every year a close positive correlation (P=0.1%) could be observed between the moisture content in late September and the rate of drying down in October. Linear regression was used each year to determine the equilibrium moisture content, to which the moisture content of kernels returned if they contained less than this quantity of water in late September and harvesting was delayed. In the experimental years this value ranged from 15.24-19.01%.

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