scholarly journals Effect of Water Repellents on Hygroscopicity and Dimensional Stability of Densified Fir and Aspen Woods

2020 ◽  
Vol 71 (1) ◽  
pp. 29-40
Author(s):  
Huseyin Pelit ◽  
Fatih Emiroglu
Keyword(s):  
High Temperature ◽  
Dimensional Stability ◽  
Atmospheric Pressure ◽  
Linseed Oil ◽  
Vacuum Treatment ◽  
Densified Wood ◽  
Water Repellent ◽  
Compression Rate ◽  
Thickness Swelling ◽  
Water Repellents

This study investigated the effect of pre-impregnation with water-repellent agents on the hygroscopicity and dimensional stability of fir (Abies bornmulleriana Mattf.) and aspen (Populus tremula L.) woods. After pre-vacuum treatment, the samples were impregnated at atmospheric pressure with paraffin, linseed oil and styrene, and then densified at compression rates of 20 % and 40 % at 120, 150 and 180 °C. The results showed that water repellents significantly affected the hygroscopicity and dimensional stability of the densified wood samples. Compression recovery rate (CRR), thickness swelling (TS), equilibrium moisture content (EMC), and water absorption (WA) values of the densified samples decreased with impregnation pretreatments. The linseed oil treatment gave more positive CRR and TS results than paraffin. Lower EMC and WA values were found in the paraffin-treated samples. However, the most successful results for all tested properties were determined in the styrene pretreated samples in which hygroscopicity decreased and dimensional stability increased (especially for aspen) due to increases in the compression rate and temperature related to densification conditions. In the styrene pretreated samples, the high temperature (180 °C) and compression rate (40 %) significantly reduced CRR, TS, EMC and WA, total dimensional stability was nearly achieved and the water repellent effectiveness was close to 100 %.

scholarly journals Density, hardness and strength properties of densified fir and aspen woods pretreated with water repellents

Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hüseyin Pelit ◽  
Fatih Emiroglu
Keyword(s):  
Compression Ratio ◽  
Bending Strength ◽  
Linseed Oil ◽  
Vacuum Treatment ◽  
Strength Properties ◽  
Aspen Wood ◽  
Positive Effect ◽  
Water Repellents ◽  
Impregnated Wood ◽  
Compression Temperature

AbstractIn this study, the effect of thermo-mechanical densification on the density, hardness, compression strength, bending strength (MOR), and modulus of elasticity (MOE) of fir and aspen wood pretreated with water repellents was analyzed. Wood specimens were impregnated with paraffin, linseed oil and styrene after pre-vacuum treatment. Then, the impregnated wood specimens were densified with compression ratios of 20 and 40%, and at 120, 150 and 180 °C. The results indicated that the density, hardness and strength properties of the all densified specimens (untreated and impregnated) increased depending on the compression ratio and temperature. For all tested properties, higher increases were obtained in the paraffin and styrene pretreated specimens compared to untreated samples. However, the increase rates in linseed oil pretreated specimens were generally lower than untreated specimens. Regarding water repellents the most successful results in all tested properties were determined in styrene pretreated specimens. The density, hardness and strength properties of all specimens increased with the increase in compression ratio. On the other hand, the increase in the compression temperature negatively affects the properties of untreated and linseed oil pretreated specimens, while having a generally positive effect on the properties of paraffin pretreated specimens. However, all tested properties of styrene pretreated specimens have increased significantly due to the increase in compression temperature. The increasing strength properties of wood as a result of densification have increased much more with paraffin and especially styrene pretreatment. These combinations can be considered as an important potential for applications that require more hardness and strength.

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 Improved Water Repellency and Dimensional Stability of Wood via Impregnation with an Epoxidized Linseed Oil and Carnauba Wax Complex Emulsion

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 271
Author(s):  
Jinyu Chen ◽  
Yujiao Wang ◽  
Jinzhen Cao ◽  
Wang Wang
Keyword(s):  
Dimensional Stability ◽  
Linseed Oil ◽  
Average Particle Size ◽  
Water Repellency ◽  
Water Repellent ◽  
Average Particle ◽  
Poplar Wood ◽  
Carnauba Wax ◽  
Natural Wood ◽  
Epoxidized Linseed Oil

Natural wood is susceptible to moisture during its practical use, limiting not only service life but also the range of uses. In this study, plant extracts, specifically linseed oil and carnauba wax (both environmentally friendly and water-repellent substances), were examined as a means to mitigate limitations of natural wood. Stable and homogenous epoxidized linseed oil/carnauba wax emulsions with an average particle size less than 230 nm were used as a modifier to enhance the performance of wood. Weight percentage gain, bulking coefficient, micromorphology, chemical structure, moisture adsorption, contact angle, water repellency, and dimensional stability of treated wood were measured. Using a scanning electron microscope (SEM), it was observed that carnauba wax and epoxidized linseed oil acted as a mechanical barrier and could partially cover or block vessels, pits, and wood rays. Furthermore, the hydrophobicity of wood increased significantly after emulsion impregnation. However, there was no obvious chemical reaction between epoxidized linseed oil and the main components of wood in the Fourier transform infrared spectroscopy (FTIR) results. The combined effect of epoxidized linseed oil and carnauba wax was apparent in both decreased water absorption and dimensional deformation. Poplar wood impregnated with an epoxidized linseed oil/carnauba wax complex emulsion shows potential for improving water-related properties. Thus, the complex emulsion modification can improve the inherent shortcoming of poplar wood effectively.

FLAVOUR REVERSION IN HYDROGENATED LINSEED OIL: I. THE PRODUCTION OF AN ISOMER OF LINOLEIC ACID FROM LINOLENIC ACID

1944 ◽  
Vol 22f (6) ◽  
pp. 191-198 ◽  
Author(s):  
H. W. Lemon
Keyword(s):  
Fatty Acids ◽  
Linoleic Acid ◽  
High Temperature ◽  
Iodine Number ◽  
Spectral Method ◽  
Linolenic Acid ◽  
Linseed Oil ◽  
Naturally Occurring ◽  
Total Fatty Acids ◽  
Isomeric Acid

Linseed oil that has been hydrogenated to a plastic consistency is subject to a type of deterioration termed "flavour reversion" when heated to temperatures used in baking or frying. Investigation of the course of hydrogenation of linseed oil by the spectral method of Mitchell, Kraybill, and Zscheile (11) has indicated that linolenic acid is converted to an isomeric linoleic acid; this acid differs from naturally occurring linoleic acid in that the double bonds are in such positions that diene conjugation is not produced by high-temperature saponification. In a typical hydrogenation, the concentration of the isomeric acid increased to a maximum, at about iodine number 120, of 18% of the total fatty acids, and at iodine number 80, at which point the plasticity was similar to that of a commercial shortening, the concentration of the isomer was 13%. Evidence is presented that the isomeric linoleic acid in partially hydrogenated linseed oil is responsible for the unpleasant flavour that develops when the oil is heated.

scholarly journals Influence of vacuumetric pressure on thermal properties of high-temperature radioactive graphite-nitrogen system

2021 ◽  
Vol 2119 (1) ◽  
pp. 012095
Author(s):  
M R Shavaleev ◽  
N M Barbin ◽  
D I Terentyev ◽  
S I Osipenko ◽  
D S Belkin
Keyword(s):  
Thermal Properties ◽  
High Temperature ◽  
Atmospheric Pressure ◽  
Thermodynamic Data ◽  
Nitrogen Atmosphere ◽  
Vacuum Pressure ◽  
Radioactive Graphite ◽  
Reactor Graphite ◽  
High Temperature Processing

Abstract To improve and specify the method proposed by the authors for high-temperature processing of reactor graphite in a nitrogen atmosphere, the thermodynamic data of the formed nitride compounds are supplemented and the system is calculated at a vacuum pressure of 0.5 atm. The data obtained are compared with the values at atmospheric pressure.

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