scholarly journals DEVELOPMENT OF A COMPOSITIONAL MODIFIER FOR MODIFICATION OF WOOD BY SPECIFIED PROPERTIES

2020 ◽  
Vol 8 (1) ◽  
pp. 17-22
Author(s):  
Aleksey Aksenov ◽  
Sergey Malyukov ◽  
A. Solntsev
Keyword(s):  
Water Absorption ◽  
Dimensional Stability ◽  
Filter Paper ◽  
Atmospheric Pressure ◽  
Moisture Absorption ◽  
Friction Units ◽  
Environmental Requirements ◽  
Impregnated Wood ◽  
Modified Wood

In recent years, the production of modified wood has been actively developing abroad. This article discusses the composition of a complex modifier for modified wood, which will improve the performance of friction units with bearings made of modified wood by reducing intermolecular interactions between contacting bodies, increase dimensional stability and hardness of modified wood, and will also comply with environmental requirements. The density of the liquid components of the impregnating compositions was determined. The number of components necessary for the preparation of impregnating compositions was calculated. The impregnation technology is as follows: the impregnating composition is poured into a tin can, heated on an electric stove to 120 0C. Prepared (dried, weighed, measured on three sides and marked) samples of 15 pieces in each impregnating composition are immersed in a hot impregnating solution. Tin cans with samples are placed in a pre-heated autoclave, closed, and brought to a pressure of 40 atm. At this pressure, the samples are kept for 5 minutes. Then the pressure is brought to atmospheric pressure, the samples are removed, dried with filter paper and placed in a desiccator for cooling to a temperature of 20 ± 2 0С. After cooling, the samples are weighed on an analytical balance to the nearest 0.002 g and the three sides of the sample are measured with a caliper. The quality of impregnation of the samples was determined. Water absorption, moisture absorption, linear swelling of the samples of impregnated wood were determined.

Thermal modification of Southern pine combined with wax emulsion preimpregnation: effect on hydrophobicity and dimensional stability

Holzforschung ◽  
2015 ◽  
Vol 69 (4) ◽  
pp. 405-413 ◽  
Author(s):  
Wang Wang ◽  
Yuan Zhu ◽  
Jinzhen Cao ◽  
Xi Guo
Keyword(s):  
Water Absorption ◽  
Dimensional Stability ◽  
Photoelectron Spectroscopy ◽  
Water Repellency ◽  
Solid Content ◽  
Thermal Modification ◽  
Paraffin Wax ◽  
Southern Pine ◽  
Thermally Modified Wood ◽  
Modified Wood

Abstract The aim of this study was to enhance the water repellency and dimensional stability of thermally modified wood by combining the preimpregnation of paraffin wax emulsion. To achieve this, Southern pine (SP; Pinus spp.) samples were first impregnated with paraffin wax emulsion (with 2.0% solid content) and then subjected to thermal modification (TM) in an oven at 180°C and 220°C for 4 and 8 h. The contact angle (CA), surface free energy, water absorption rate (WAR), anti-swelling efficiency (ASE), and bending properties of the control and modified samples were investigated. Moreover, the chemical and morphological alterations were analyzed by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Both the wax impregnation and TM decreased the surface wettability, water absorption, and tangential swelling, while the combination of wax and thermal treatment exhibited the best water repellency and dimensional stability, indicating the synergism between the two procedures. However, the wax preimpregnation did not affect the mechanical properties of thermally modified wood. The FTIR, SEM, and XPS analyses confirmed that the synergistic effect is mainly due to the redistribution of the paraffin wax during TM rather than its impact on the chemical changes caused by thermal degradation.

scholarly journals A comparative study on the effects of linseed oil and shellac treatment on the hygroscopicity, dimensional stability, and color changes of Chinese ash wood

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 8085-8092
Author(s):  
Mihaela Liu ◽  
Xinwei Tu ◽  
Xinyou Liu ◽  
Zhihui Wu ◽  
Jiufang Lv ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Moisture Absorption ◽  
Linseed Oil ◽  
Morphological Characteristics ◽  
Treated Wood ◽  
Water Repellency ◽  
Wood Products ◽  
Color Changes

Linseed oil and shellac are natural, environmentally friendly materials with good water repellency. They were used to impregnate Chinese ash wood at room temperature (20 °C) using a vacuum-pressure procedure (consisting of three cycles of 0.01 MPa for 1.5 h and atmospheric pressure for 1.5 h) to improve the dimensional stability of wood. The effects of the impregnation treatment on wood color changes, dimensional stability, moisture absorption, and morphological characteristics were evaluated. The linseed oil and shellac treatment improved the dimensional stability of wood. Linseed oil and shellac displayed good permeability in Chinese ash wood, with weight gains of 21.7% and 19.0%, respectively, after impregnation. The swelling coefficients of treated wood in the tangential and radial directions decreased by 15 to 22%, indicating that impregnation improved the dimensional stability of wood. Linseed oil and shellac solidified and occluded the pits within the wood interior to prevent moisture absorption. This method can be used to improve the dimensional stability of a variety of wood products, such as buildings, furniture, and landscape architecture.

scholarly journals Improving Hydrophobicity of Tropical Hardwood along Axial Positions

2021 ◽  
Vol 25 (8) ◽  
pp. 1339-1343
Author(s):  
O.A. Adegoke ◽  
F.G. Adebawo ◽  
O.O. Ajala ◽  
E.A. Adelusi ◽  
A.J. Oloketuyi
Keyword(s):  
Water Absorption ◽  
Dimensional Stability ◽  
Weight Percent Gain ◽  
Weight Percent ◽  
Axial Position ◽  
Water Repellent ◽  
Tropical Hardwood ◽  
Acetyl Group ◽  
Percentage Of Water Absorption ◽  
Modified Wood

Wood is hygroscopic and is considered dimensionally unstable materials when exposed to wet conditions. To increase the hydrophobicity of wood, this study focused on the modification of tropical hardwood (Triplochiton scleroxylon) along different positions of the stem using acetic anhydride The weight percent gain (WPG) was determined and acetylation reaction was confirmed with FTIR. The dimensional stability of the wood was characterized by water absorption (WA), volumetric swelling (VS), anti-swelling efficiency (ASE), and water repellent efficiency (WRE). Data obtained were subjected to analysis of variance at α0.05. It was observed that the weight gain (WG) by acetylation increases along the axial position (base to top) of T. scleroxylon wood. IR-spectra confirmed properly the substitution of the acetyl group. The treatment resulted in a marked improvement in the WA and VS, ASE, and WRE of acetylated T. scleroxylon wood were also found to improve considerably from base to top of the wood. It could be said that the WPG and hydrophobicity increased, but the percentage of water absorption and volumetric swelling diminished. Hence, the modified wood showed good hydrophobicity and improved dimensional stability.

Study on Properties of Modified Poplar Wood

2014 ◽  
Vol 926-930 ◽  
pp. 242-245
Author(s):  
Yong Wang ◽  
Ze Jun Chen ◽  
La Yun Deng ◽  
You Hua Fan
Keyword(s):  
Mechanical Properties ◽  
Comparative Study ◽  
Water Absorption ◽  
Dimensional Stability ◽  
Physical And Mechanical Properties ◽  
Dry Density ◽  
Poplar Wood ◽  
Absorption Ratio ◽  
Different Levels ◽  
Modified Wood

The paper based on a comparative study between poplar wood and modified poplar wood, concerning dimensional stability, physical and mechanical properties. The result showed that air-dry density and ASE value of modified wood samples were increasing in different levels with change of the modifier concentration, compared with untreated poplar wood. The air-dry density of modified wood reached 0.41 g/cm3 with increase of 5.3% compared to poplar wood. ASE reached 47.8% and the water-absorption ratio decreased by 38% at most when the modifier concentration was 30 wt.%. Moreover, the MOE and MOR of modified poplar wood increased up to 27.4% and 13% respectively when the modifier concentration was 25 wt.%. The SEM spectrum showed some wood rays and the gaps between staggered fibers were filled by modifier.

Study on the Impact of Two Kinds Modification Methods on the Dimensional Stability of Poplar

2013 ◽  
Vol 341-342 ◽  
pp. 42-48
Author(s):  
Zhi Bo Feng ◽  
Guo Zheng Zou ◽  
Gang Chen ◽  
Jia Bin Cai
Keyword(s):  
Water Absorption ◽  
Dimensional Stability ◽  
Absorption Rate ◽  
Moisture Absorption ◽  
Tangential Direction ◽  
Resistance Rate ◽  
Shrinkage Rate ◽  
Control Group ◽  
Swelling Rate ◽  
The Impact

Fast-growing poplars are used as test materials in this study, which are respectively first carbonized then impregnated treatment and carbonized treatment, to test the dimensional stability of modified wood. The results show: the shrinkage rate of specimen which is first carbonized then impregnated is higher than the control group as much as 87.80% ~ 89.16% in radical direction, 76.20%~82.43% in tangential direction; from oven-dry state to air-dry state, the swelling rate of specimen is higher than the control group as much as 5.26% , 9.09%, and to saturated state, the rate is lower than the control group as 14.55% and 0.13% respectively in radical direction and tangential direction, as a result, the characters of shrinkage and swelling are not improved. When carbonized, the shrinkage rate of specimen is lower than the control group as 3.01%~8.47% and 5.08%~5.86% respectively in radical direction and tangential direction; the swelling rate is lower than control group as 23.84%~41.05% and 12.01%~43.75% respectively in radical direction and tangential direction, as a result, the character of shrinkage is poorly improved but swelling is obviously improved. After the two modified treatments, moisture absorption rate is respectively 6.99% and 4.91%, both lower than the control group8.80%; moisture resistance rate respectively 20.57% and 44.20%; water absorption rate 107.27% and 123.74%, lower than the control group 210%; resistance to water absorption up to 48.92% and 41.08%. Know then, carbonization treatment is better in terms of the affect on improving dimensional stability of wood.

scholarly journals OPTIMIZATION OF PROTECTIVE COATING COMPONENTS OF THERMOMODIFIED WOOD TO THE EXPOSURE OF WATER

2021 ◽  
pp. 101-109
Author(s):  
Yu. Tsapko ◽  
◽  
A.Yu. Gorbachova ◽  
S.N. Mazurchuk ◽  
O. Bondarenko ◽  
...  
Keyword(s):  
Water Absorption ◽  
Protective Coating ◽  
Moisture Absorption ◽  
Thermal Modification ◽  
Wood Products ◽  
Operating Conditions ◽  
Photochemical Degradation ◽  
Thermally Modified Wood ◽  
Wood Surfaces ◽  
Modified Wood

Abstract. Paints and varnishes are used to a large extent to protect wood surfaces in outdoor conditions, as they are easy to maintain and reapply. Also, when developing a coating, manufacturers are guided by the need to obtain a number of properties that generally determine its ability to protect against moisture. To obtain a protective coating that meets the specified requirements, it is necessary that the components that make up the coating belong directly to the group of protective materials or form such compounds under operating conditions, be able to adhere to the surface of the product. It was found that thermal modification provides a decrease in water absorption of wood. Additional processing of the wood surface helps to reduce moisture absorption by 2 times, and for samples modified at a temperature of 220 °C – 3 times. Geometric dimensional stability is also improved by a factor of 2. The effect of heat treatment on the water absorption of wood is somewhat less – for samples modified at 190 and 220 °C for more than 10 hours. Protective substances for thermally modified wood provided similar protection of open thermally modified surfaces of wood from the effects of water. The positive effect of thermal modification on a decrease in the level of water absorption has been established. It has been proven that it is temperature that has a significant effect on such changes. Since the protective coating is also susceptible to photochemical degradation, it is very important to renew it in a timely manner in accordance with the manufacturer's instructions for the pleasant appearance of wood surfaces during external use. The optimal ratio of components in the surface layer of thermally modified wood has been determined, which ensures the fulfillment of the task, namely for a mixture of oil and wax: the density of a wood – 724 kg/m3; oils – 70.0%; wax – 17.5%. Therefore, such treatment is beneficial for the protection and aesthetic appeal of wood products.

Evidence for direct water absorption by the shoot of the desiccation-tolerant plant Vellozia flavicans in the savannas of central Brazil

2005 ◽  
Vol 21 (5) ◽  
pp. 585-588 ◽  
Author(s):  
Rafael S. Oliveira ◽  
Todd E. Dawson ◽  
Stephen S. O. Burgess
Keyword(s):  
Water Absorption ◽  
Moisture Absorption ◽  
Terrestrial Plants ◽  
Desert Ecosystems ◽  
Common View ◽  
Central Brazil ◽  
Tolerant Plants ◽  
Aerial Roots ◽  
Alternative Water ◽  
Specialized Structure

Our common view on water uptake by terrestrial plants is that it occurs via absorption by roots from the soil substrate. However, it has long been known that plants exhibit alternative water-absorption strategies, particularly in drought-prone environments. Examples include many tropical epiphytic orchids which use a specialized structure called velamen radicum around their aerial roots for moisture absorption directly from the air (Capesius & Barthlott 1975), specialized trichomes in bromeliads (Andrade 2003, Benzing 1990), uptake by hydathodes into leaves of species inhabiting dry desert ecosystems of Namibia (Martin & von Willert 2000) and foliar absorption by coastal California redwoods during the summer fog season (Burgess & Dawson 2004). One of the most intriguing and yet, least-studied examples of adaptations to severe water limitation is found with desiccation-tolerant plants (also called resurrection plants). During drought periods, the water content of these plants can equilibrate with the low relative humidity of the air to the point that the plants appear dead. However, when water is supplied, these plants fully rehydrate (Alpert 2000, Bewley & Krochko 1982) and become physiologically active. Desiccation-tolerant vascular plants are rare in most ecosystems but diverse in tropical inselbergs (granitic outcrops; Porembski & Barthlott 2000). Relatively little is known about inselberg species particularly from an ecophysiological perspective (see Lüttge 1997 and Klüge & Brulfert 2000 for reviews).

The Effect of Ge Segregation on Oxidation of Si

1987 ◽  
Vol 105 ◽  
Author(s):  
E. C. Frey ◽  
N. R. Parikh ◽  
M. L. Swanson ◽  
M. Z. Numan ◽  
W. K. Chu
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Epitaxial Layer ◽  
Atmospheric Pressure ◽  
Oxidation Rate ◽  
Oxidation Temperature ◽  
Pressure Oxidation ◽  
Enhanced Oxidation ◽  
High Pressure Oxidation

AbstractWe have studied oxidation of various Si samples including: Ge implanted Si, CVD and MBE grown Si(0.4–4% Ge) alloys, and MBE grown Si-Si(Ge) superlattices. The samples were oxidized in pyrogenic steam (800–1000°C, atmospheric pressure) and at low temperature and high pressure (740°C, 205 atm of dry O2). The oxidized samples were analyzed with RBS/channeling and ellipsometry.An enhanced oxidation rate was seen for all Ge doped samples, compared with rates for pure Si. The magnitude of the enhancement increased with decreasing oxidation temperature. For steam oxidations the Ge was segregated from the oxide and formed an epitaxial layer at the Si-SiO2 interface; the quality of the epitaxy was highest for the highest oxidation temperatures. For high pressure oxidation the Ge was trapped in the oxide and the greatest enhancement in oxidation rate (>100%) was observed.

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