Journal articles: 'Densified wood'

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Navi, Parviz, and Fred Girardet. "Effects of Thermo-Hydro-Mechanical Treatment on the Structure and Properties of Wood." Holzforschung 54, no. 3 (April 13, 2000): 287–93. http://dx.doi.org/10.1515/hf.2000.048.

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Summary A process has been developed for densifying wood by thermo-hydro-mechanical (THM) means. The resulting product is then called THM densified wood. Small specimens of different wood species, with or without knots, were densified in their radial, tangential and transversal directions. Tests on THM densified wood show significant improvement in mechanical properties. THM densified wood is less hygroscopic and more stable, with almost no shape memory. We have shown that the shear strength of wood in its grain direction increases more than tenfold by THM treatment. This article gives testing results and micrographs of THM densified wood, and discusses the physical nature of different mechanisms intervening at the wood cell wall level during the thermo-hydro-mechanical process.

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Schwarze, Francis W. M. R., and Melanie Spycher. "Resistance of thermo-hygro-mechanically densified wood to colonisation and degradation by brown-rot fungi." Holzforschung 59, no. 3 (May 1, 2005): 358–63. http://dx.doi.org/10.1515/hf.2005.059.

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Abstract Colonisation and wood degradation by three brown-rot fungi, Coniophora puteana, Gloeophyllum trabeum and Poria placenta, were studied in wood of Norway spruce (Picea abies) subjected to three different treatments: hygro-thermal (TH) (160 and 180°C), mechanical densification and thermo-hygro-mechanical (THM) treatment including densification and post-treatment under saturated steam conditions at different temperatures (140, 160 and 180°C). The weight loss induced by all three fungi was lowest in THM-densified wood post-treated at 180°C. Highest weight losses were recorded for controls and TH-treated wood. Fungal colonisation varied in its intensity, depending on the treatment applied to the wood. Hyphal growth in controls and TH-treated wood was abundant, whereas in densified and THM-densified wood it was sparse and confined predominantly to the cell lumina of earlywood tracheids. Also, penetration of large-diameter hyphae and associated degradation in THM-densified wood was impeded by occlusion of the lumina, associated with irreversible compression (loss in shape memory). In contrast to C. puteana and P. placenta, which showed typical brown-rot behaviour, G. trabeum frequently showed hyphal tunnelling within the secondary walls of tracheids and xylem ray parenchyma of controls and thermally treated wood. Such growth was never observed in THM-densified wood post-treated at 180°C.

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Xiang, Elin, Rongfeng Huang, and Shumin Yang. "Change in Micromechanical Behavior of Surface Densified Wood Cell Walls in Response to Superheated Steam Treatment." Forests 12, no. 6 (May 28, 2021): 693. http://dx.doi.org/10.3390/f12060693.

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The combination of surface densification and superheated steam treatment is an effective method to improve the mechanical properties and dimensional stability of low-density wood. The objective of the current work is to evaluate the effects of superheated steam treatment on the micromechanical behavior of surface densified wood. The microstructure, chemical composition, cellulose crystalline structure, and micromechanical behavior of surface densified wood under different superheated steam pressures were investigated. Results indicated that both 0.1 MPa and 0.3 MPa superheated steam treatments increased the elastic modulus and hardness of fiber cell walls in surface densified wood. However, the average creep ratio and maximum creep compliance J(50) of surface densified wood under 0.3 MPa decreased by 41.59% and 6.76%, respectively, compared with untreated wood. The improvement of elastic modulus, hardness and creep resistance of surface densified wood treated with superheated steam was associated with the increase of relative crystallinity (CrI) and crystalline size. In addition, 0.3 MPa superheated steam treatment displayed a better effect on the enhancement of the elastic modulus, hardness, and creep resistance of the fiber cell wall than 0.1 MPa superheated steam treatment.

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RADOMSKI, ANDRZEJ, and MARTA GNACIŃSKA. "The study of the impact of in situ polymerisation with styrene or acrylates on water absorbability and swelling of thermomechanically densified poplar wood." Annals of WULS, Forestry and Wood Technology 108 (October 31, 2019): 140–47. http://dx.doi.org/10.5604/01.3001.0013.7701.

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The study of the impact of in situ polymerisation with styrene or acrylates on water absorbability and swelling of thermomechanically densified poplar wood. Black poplar samples, which were previously subjected to thermomechanical densification, were tested for an improvement on the field of water resistance. Series of samples were additionally thermally treated in a nitrogen atmosphere, and then series of densified only or densified and thermally treated samples were treated with monomer mixtures, containing styrene or acrylates, and co-monomers reactive toward cell wall of wood, followed by thermally induced radical polymerisation. All samples were tested by prolonged soaking in water, while volume swelling and absorbability were determined. Densified wood proved to be suitable for modification by in situ polymerisation. Thermally treated densified wood was found to be significantly more compatible with polymers used, as a decrease in its swelling was observed as dominant effect, while absorbability changes were less clear.

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Mania, Przemysław, Miłosz Wróblewski, Adam Wójciak, Edward Roszyk, and Waldemar Moliński. "Hardness of Densified Wood in Relation to Changed Chemical Composition." Forests 11, no. 5 (May 1, 2020): 506. http://dx.doi.org/10.3390/f11050506.

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The aim of this study was to evaluate some of the properties of densified poplar and birch wood earlier subjected to partial delignification of cell walls. The effects of delignification are presented as a comparison of the content of basic structural components in wood before and after chemical modification. In birch wood, the lignin content decreased by 20%, while that of cellulose decreased by 9.7% and that of hemicellulose decreased by 64.9%. In poplar, the lignin content decreased by 34.1%, that of cellulose decreaed by 13.5%, and that of hemicellulose decreased by 58.0%. The hardness of densified birch and poplar wood, after partial reduction of chemical components, was 147 and 111 MPa, respectively, and, compared with natural (non-densified) wood, was almost 4.5 times and 7 times higher, respectively. Poplar wood was more densified (without delignification 238% and after delignification 281%). In the case of birch wood, the density levels were 176% and 188%, respectively.

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Laine, Kristiina, Kristoffer Segerholm, Magnus Wålinder, Lauri Rautkari, Graham Ormondroyd, Mark Hughes, and Dennis Jones. "Micromorphological studies of surface densified wood." Journal of Materials Science 49, no. 5 (December 3, 2013): 2027–34. http://dx.doi.org/10.1007/s10853-013-7890-8.

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Jakob, Matthias, Gregor Stemmer, Ivana Czabany, Ulrich Müller, and Wolfgang Gindl-Altmutter. "Preparation of High Strength Plywood from Partially Delignified Densified Wood." Polymers 12, no. 8 (August 11, 2020): 1796. http://dx.doi.org/10.3390/polym12081796.

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Wood and natural fibers exhibit an advantageous combination of good mechanics at comparably low density. Nevertheless, comparing absolute strength and stiffness, wood is clearly inferior to materials such as metals and engineered composites. Since there is a strong correlation between wood density and wood mechanical performance, densification by transversal compression suggests itself as a route towards improved mechanics. Partially delignified densified spruce veneers with excellent tensile properties were produced by means of an alkaline (AL) and an organosolv (OS) approach. Plywood specimens were manufactured using treated veneers glued with a phenol-resorcinol-formaldehyde adhesive and were compared with plywood samples made of native spruce veneers (Ref) and spruce veneer densified after plasticization by water impregnation (H2O). Roughly, the bending strength and the modulus of elasticity of plywood from partially delignified densified wood were improved by a factor of 2.4 and 3.5, respectively. Interlaminar shear strength did not match this improvement after partial delignification. Together with excessive thickness swelling, this might be a drawback of partially delignified densified wood in need for further research.

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Neyses, Benedikt, Olov Karlsson, and Dick Sandberg. "The effect of ionic liquid and superbase pre-treatment on the spring-back, set-recovery and Brinell hardness of surface-densified Scots pine." Holzforschung 74, no. 3 (February 25, 2020): 303–12. http://dx.doi.org/10.1515/hf-2019-0158.

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AbstractCompressing the surface of sawn timber results in a substantial increase in hardness, and this opens up new market opportunities of using low-density timber species as the raw material for high-value wood products. Unfortunately, widespread commercialisation is hindered by the lack of an industrially viable surface densification process, the major obstacle being the set-recovery (SR) of the densified wood cells upon exposure to moisture. Our hypothesis is that partial dissolution of the crystalline cellulose during densification will largely prevent the SR of densified wood. We therefore evaluated the effect of ionic liquid (IL) or organic superbase pre-treatment on the elastic spring-back (SB), SR and Brinell hardness (HB) of surface-densified wood. Specimens of Scots pine were treated with solutions of ILs or superbases, and then densified in a hot press at temperatures between 200°C and 270°C. The SR was reduced from 90% for the control group to only about 10% for the treated materials. The treated and densified specimens exhibited a higher HB than their untreated and densified counterparts. The method presented in this study is a precursor to the development of a continuous densification process adapted for an open system. Further studies are needed to understand the underlying mechanisms of the pre-treatment.

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Laskowska, Agnieszka, and Janusz W. Sobczak. "Surface chemical composition and roughness as factors affecting the wettability of thermo-mechanically modified oak (Quercus robur L.)." Holzforschung 72, no. 11 (November 27, 2018): 993–1000. http://dx.doi.org/10.1515/hf-2018-0022.

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AbstractEuropean oak wood (W) was thermo-mechanically modified (TM) via densifying at 100 and 150°C and the surface properties of the TMW were investigated. The contact angle (CA) of the wood with the reference liquids water and diiodomethane was determined using the sessile drop method. The surface free energy of the TMW on tangential sections within the first 60 s after applying a drop was analyzed. The roughness parameters Ra and Rz parallel (‖) and perpendicular (⊥) to the grain were investigated. The wettability analysis showed that densified wood had a higher CA and lower work of adhesion and surface free energy than non-densified wood. An X-ray photoelectron spectroscopy [XPS or electron spectroscopy for chemical analysis (ESCA)] analysis showed that the oxygen to carbon atoms ratio (O/C ratio) of densified wood surface was lower than that of non-densified wood. The carbon C1-C2 atoms ratio (C1/C2 ratio) increased with increasing TM temperature. The results were interpreted as being that extractives migrate to the surface and amorphous and glassy polymers, i.e. lignin and hemicelluloses, in wood are rearranged. Increasing densification temperature makes TMW surfaces more hydrophobic.

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Jakob, Matthias, Jakob Gaugeler, and Wolfgang Gindl-Altmutter. "Effects of Fiber Angle on the Tensile Properties of Partially Delignified and Densified Wood." Materials 13, no. 23 (November 27, 2020): 5405. http://dx.doi.org/10.3390/ma13235405.

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Partial delignification and densification provide a pathway to significant improvement in the mechanical performance of wood. In order to elucidate potential effects of this treatment on the mechanical anisotropy of wood, partially delignified and densified spruce wood veneers were characterized at varying degrees of off-axis alignment. While the tensile strength and the modulus of elasticity (MOE) were clearly improved in parallel to the axis of wood fibers, this improvement quickly leveled off at misalignment angles ≥30°. For transverse tensile strength, the performance of alkaline-treated and densified wood was even inferior to that of untreated wood. Microscopic examination revealed the presence of microscopic cracks in treated wood, which are assumed to be responsible for this observation. It is concluded that impaired transverse tensile properties are a weakness of partially delignified and densified wood and should be considered when a potential usage in load-bearing applications is intended.

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Fu, Qilan, Alain Cloutier, and Aziz Laghdir. "Heat and Mass Transfer Properties of Sugar Maple Wood Treated by the Thermo-Hygro-Mechanical Densification Process." Fibers 6, no. 3 (July 24, 2018): 51. http://dx.doi.org/10.3390/fib6030051.

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This study investigated the evolution of the density, gas permeability, and thermal conductivity of sugar maple wood during the thermo-hygro-mechanical densification process. The results suggested that the oven-dry average density of densified samples was significantly higher than that of the control samples. However, the oven-dry density did not show a linear increase with the decrease of wood samples thickness. The radial intrinsic gas permeability of the control samples was 5 to 40 times higher than that of densified samples, which indicated that the void volume of wood was reduced notably after the densification process. The thermal conductivity increased by 0.5–1.5 percent for an increase of one percent moisture content for densified samples. The thermal conductivity of densified wood was lower than that of the control samples. The densification time had significant effects on the oven-dry density and gas permeability. Both densification time and moisture content had significant effects on thermal conductivity but their interaction effect was not significant.

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Siahaan, Herianto, and Imam Wahyudi. "Keragaan Permesinan dan Keteguhan Rekat Kayu Jati Cepat Tumbuh Terdensifikasi." Jurnal Ilmu Pertanian Indonesia 26, no. 1 (December 7, 2020): 1–7. http://dx.doi.org/10.18343/jipi.26.1.1.

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The objective of this study was to analyze machining performance (characteristic and quality), as well as bonding quality of densified wood, and then compared to those of un-treated (control) wood and boron-treated wood. Characteristic and quality of machining properties were directly evaluated by qualified technician during processing, while bonding quality was evaluated through its shear strength. The results showed that densification employed was able to improve machining performance and bonding quality of the 5-year-old faster-grown teakwood. Compared to control wood and boron-treated wood, machining performances of densified teakwood are greater, while bonding quality increased by 18.79 and 26.86%, respectively. The surface became much fine and even, and has similar colour to older teakwood. Analysis hierarchy process (AHP) proves that densified teakwood is the best raw material for furniture manufacturing since its machining performances, appearance, colour, and bonding quality are better either than control wood or boron-treated wood. Keywords: AHP, bonding quality, densification, faster-grown teakwood, machining performance

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Tenorio, Carolina, and Roger Moya. "Effect of thermo-hydro-mechanical densification on the wood properties of three short-rotation forest species in Costa Rica." BioResources 15, no. 4 (September 7, 2020): 8065–84. http://dx.doi.org/10.15376/biores.15.4.8065-8084.

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Alnus acuminata, Vochysia ferruginea, and Vochysia guatemalensis are three low-density wood species used for reforestation in Costa Rica. The goal of this work was to study a thermo-hydro-mechanical densification process and test the characteristics of densified wood of these species. Twelve densifying treatments based on temperature, compression time, and use/no use of steam were tested. The variables of the densification process and the properties of the densified wood were determined. The results showed that the densification percentage was over 80% for wood of A. acuminata and over 70% for wood of V. ferruginea and V. guatemalensis. In the three species, the densification process was influenced by initial density. The influence of temperature during the densification process affected the heating rate and color change. An increase in the modulus of elasticity and modulus of rupture in static bending and in the hardness of the densified wood relative to the normal wood was observed, as well as a clear positive correlation of the properties with final density and maximum load, the latter being highly correlated with initial density. This showed that initial density was significant in the densification process and affects wood properties.

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Fu, Qilan, Alain Cloutier, and Aziz Laghdir. "Effects of heat and steam on the mechanical properties and dimensional stability of thermo-hygromechanically-densified sugar maple wood." BioResources 12, no. 4 (October 19, 2017): 9212–26. http://dx.doi.org/10.15376/biores.12.4.9212-9226.

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Effects of heat and steam were investigated relative to the mechanical properties and dimensional stability of thermo-hygromechanically-densified sugar maple wood (Acer saccharum Marsh.). The densification process was performed at four temperatures (180 °C, 190 °C, 200 °C, and 210 °C) with and without steam. The hardness, bending strength, bending stiffness, and compression set recovery of the control and densified samples were determined. The effects of heat and steam on the density profile of the samples across thickness were also investigated. The results suggested that the effects of steam on the mechanical properties and dimensional stability of sugar maple wood were more important than that of heat’s influence. Compared to the samples densified without steam, the samples densified with steam showed higher values for hardness, bending strength, bending stiffness, compression set, and density, but much lower compression set recovery when treatment temperature was below 200 °C. High temperature combined with steam contributed to decreased compression set recovery. The lowest compression set recovery was obtained after the first swelling/drying cycle for all of the treatments. A higher weight loss occurred at 210 °C, which resulted in a noticeable decrease of wood density.

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Fang, Chang-Hua, Alain Cloutier, Pierre Blanchet, Ahmed Koubaa, and Nicolas Mariotti. "Densification of wood veneers combined with oil-heat treatment. Part 1: Dimensional stability." BioResources 6, no. 1 (December 11, 2010): 373–85. http://dx.doi.org/10.15376/biores.6.1.373-385.

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is often a problem due to compression recovery. Alternatively, oil-heat treatment (OHT) improves wood dimensional stability and enhances resistance to biological attack. This study examined combined wood densification and OHT. Large wood veneer 700 700 mm specimens prepared with aspen (Populus tremuloides) were densified using heat, steam, and pressure at 160ºC, 180ºC, and 200°C, respectively. OHT at 180, 200ºC, and 220ºC for 1, 2, and 3h was then applied to the densified veneers. Results show that OHT efficiently improved dimensional stability and reduced compression set recovery. OHT temperature and duration markedly influenced the reduction of compression set recovery: the higher the OHT temperature and duration, the lower the recovery. Less than 5% recovery was obtained under various OHT conditions, and almost 0% recovery under some OHT conditions. Radial and tangential swellings of densified veneers were reduced dramatically. Compared to OHT duration, OHT temperature had a pronounced higher impact on radial and tangential swelling. Irreversible swelling (IS) in the compression direction of densified veneers decreased after OHT, particularly with high temperature and long duration, and anti-swelling efficiency (ASE) in the compression direction improved significantly.

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Buchelt, Beate, Tobias Dietrich, and André Wagenführ. "Testing of set recovery of unmodified and furfurylated densified wood by means of water storage and alternating climate tests." Holzforschung 68, no. 1 (January 1, 2014): 23–28. http://dx.doi.org/10.1515/hf-2013-0049.

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Abstract Densification is a well-known method for improving the mechanical properties of wood. In the present study, unmodified and furfurylated wood samples were densified and submitted to cyclic water storage tests and cyclic alternating climate tests. Swelling coefficients and spring-back data were determined for the evaluation of the quality of densification. The study shows that results depend on the test method applied. Simple water storage tests do not reflect the behavior of densified wood in the high humidity range. The spring-back data of unmodified samples are more influenced by the testing method than those of the furfurylated ones.

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Riggio, Mariapaola, Dusan Pauliny, Jakub Sandak, and Anna Sandak. "Novel Nail-Like Wood Connectors." Advanced Materials Research 778 (September 2013): 647–54. http://dx.doi.org/10.4028/www.scientific.net/amr.778.647.

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In traditional timber structures, hardwood connectors such as a nails, wedges, dowels and pegs have been used as reinforcement of carpentry joints or to fix wooden ceiling matts or floor boards. In the study reported, the possibility to rely on enhanced mechanical and technological properties of densified wood, for the production of wooden nails to be used in the repair of traditional timber structures is discussed. The wood used for connectors were domestic wood species; ash, beech, black locust and poplar. Wooden blocks were exposed to densification procedure with the purpose of increasing the materials density, dimensional stability and possibly, improve durability and selected mechanical properties. The densification ratio varied between 50 and 67%. A dedicated research has been performed in order to determine the effect of densification on the compression behavior of wood in the form of nails. The progress of pushing force during insertion of the wooden nails into wood samples was also monitored and served for insertion process control. A preliminary series of push-out tests have been carried out on timber-to-timber joints assembled with the densified nails.The results obtained show potential for using the novel wooden nail connectors for substitution or integration repair works in traditional timber systems.

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Chu, Demiao, Jun Mu, Stavros Avramidis, Sohrab Rahimi, Shengquan Liu, and Zongyuan Lai. "Functionalized Surface Layer on Poplar Wood Fabricated by Fire Retardant and Thermal Densification. Part 1: Compression Recovery and Flammability." Forests 10, no. 11 (October 26, 2019): 955. http://dx.doi.org/10.3390/f10110955.

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To enhance compression stability and fire retardancy of densified wood, a new modification method i.e., combined nitrogen–phosphorus (NP) fire retardant pre-impregnation with surface thermo-mechanical densification is used to fabricate a certain thickness of functionalized surface layer on poplar. This combined treated wood is investigated via vertical density profile (VDP), and the compression stability is revealed by both soaking test and cone analysis. Results demonstrate that the combined treatment hardened the surface of wood and reformed the interface combination of the NP with the wood cell wall, thus making the surface tissue more close-grained. Fire retardancy was also enhanced; the total heat release and CO generation values decreased by 21.9% and 68.4%, respectively, when compared with that of solely NP-treated wood. Moreover, surface hardness increased by 15.8%, and the recovery of surface hardness and thickness were 56.8% and 77.2% lower than that of simply densified wood. It appears that this NP-involved thermal densification could be considered as an alternative approach to enhance both the compression stability and fire resistance of wood.

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Jennings, Jessica D., Audrey Zink-Sharp, Frederick A. Kamke, and Charles E. Frazier. "Properties of compression densified wood. Part I: bond performance." Journal of Adhesion Science and Technology 19, no. 13-14 (January 2005): 1249–61. http://dx.doi.org/10.1163/156856105774429055.

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Jennings, Jessica D., Audrey Zink-Sharp, Charles E. Frazier, and Frederick A. Kamke. "Properties of compression-densified wood, Part II: surface energy." Journal of Adhesion Science and Technology 20, no. 4 (January 2006): 335–44. http://dx.doi.org/10.1163/156856106776381802.

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Shams, Md Iftekhar, and Hiroyuki Yano. "Development of selectively densified surface laminated wood based composites." European Journal of Wood and Wood Products 67, no. 2 (February 5, 2009): 169–72. http://dx.doi.org/10.1007/s00107-008-0303-z.

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Kutnar, Andreja, Lauri Rautkari, Kristiina Laine, and Mark Hughes. "Thermodynamic characteristics of surface densified solid Scots pine wood." European Journal of Wood and Wood Products 70, no. 5 (April 21, 2012): 727–34. http://dx.doi.org/10.1007/s00107-012-0609-8.

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Hajihassani, Reza, Saman Ghahri, Seyedeh Masoomeh Zamani, and Amir Nourbakhsh. "Performance of Densified Wood Glulam as Building Bio-Material." Journal of Renewable Materials 10, no. 2 (2022): 511–26. http://dx.doi.org/10.32604/jrm.2022.017781.

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Marian, G., I. Gelu, B. Istrati, A. Gudîma, B. Nazar, A. Pavlenco, A. Banari, and N. Daraduda. "Quality of pellets produced from agricultural wood residues specific to the Prut river basin." UKRAINIAN BLACK SEA REGION AGRARIAN SCIENCE 109, no. 1 (2021): 84–93. http://dx.doi.org/10.31521/2313-092x/2021-1(109)-11.

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Quality of pellets produced from agricultural wood residues specific to the Prut river basin This paper presents an overview of the prospects for the use of agricultural wood residues, specific to the climatic zone adjacent to the Prut River and the qualitative characteristics of densified solid biofuels in the form of pellets produced from the main types of the agricultural wood biomass, taken from agricultural plantations in the Republic of Moldova and Botosani, Iasi, Vaslui and Galați counties in Romania. The aim of the paper is to establish the energy potential of the main indigenous agricultural wood residues and to analyze the quality of the pellets produced from these residues. The research results showed that the pellets produced from the studied agricultural residues mainly meet ENPlus 3 requirements for most qualitative parameters, except for those produced from blackberry and currant residues. Residues from the prunning of some types of fruit shrubs can be used to produce pellets by creating mixtures of different proportions, and their qualitative characteristics can be significantly improved by thermo-chemical pre-treatment of the raw material. Keywords: plant biomass, densified solid biofuels, pellets, biofuel, energy potential, agricultural wood residues.

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Sekino, Noboru, Masafumi Inoue, Mark Irle, and Tim Adcock. "The Mechanisms Behind the Improved Dimensional Stability of Particleboards Made from Steam-Pretreated Particles." Holzforschung 53, no. 4 (July 1, 1999): 435–40. http://dx.doi.org/10.1515/hf.1999.072.

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Summary The mechanisms which cause an improvement in the dimensional stability of particleboards made from steam pretreated particles were investigated from the aspects of potential thickness recoveries of densified wood particles and the breakage of the adhesive bond network in particleboards. Since the latter would depend on the balance between bond strengths and stresses imposed on the adhesive bond, the effects of steaming temperature (160 to 220°C) on bond quality, recovery stress of compressed wood and in-plane swelling stress were investigated. Steam pretreatment was found: 1) to reduce thickness recoveries of densified wood particles, steaming temperatures above 190°C are especially effective, 2) not to cause a significant reduction in bond strength when steaming below 210°C or if relatively high press pressures of 1.5MPa are employed, 3) to reduce recovery stress of compressed wood, which is mainly caused by the increase in wood compressibility, 4) to reduce in-plane swelling stress of particles, which was found to correlate with reductions in both hygroscopicity and elasticity.

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Adachi, Koji, Yasuji Kurimoto, Hidefumi Yamauchi, and Masafumi Inoue. "Shape Change during Carbonization of Densified Wood and Its Control." Mokuzai Gakkaishi 56, no. 4 (2010): 235–42. http://dx.doi.org/10.2488/jwrs.56.235.

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Gabrielli, Chris P., and Frederick A. Kamke. "Phenol–formaldehyde impregnation of densified wood for improved dimensional stability." Wood Science and Technology 44, no. 1 (May 21, 2009): 95–104. http://dx.doi.org/10.1007/s00226-009-0253-6.

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Raman, Vinodini, and Kang Chiang Liew. "Density of Densified Paraserianthes falcataria Wood Pre-treated with Alkali." IOP Conference Series: Earth and Environmental Science 549 (September 23, 2020): 012030. http://dx.doi.org/10.1088/1755-1315/549/1/012030.

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Bekhta, Pavlo, Stanisław Proszyk, Tomasz Krystofiak, and Barbara Lis. "Surface wettability of short-term thermo-mechanically densified wood veneers." European Journal of Wood and Wood Products 73, no. 3 (March 19, 2015): 415–17. http://dx.doi.org/10.1007/s00107-015-0902-4.

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Salca, Emilia-Adela, Pavlo Bekhta, and Yaroslav Seblii. "The Effect of Veneer Densification Temperature and Wood Species on the Plywood Properties Made from Alternate Layers of Densified and Non-Densified Veneers." Forests 11, no. 6 (June 24, 2020): 700. http://dx.doi.org/10.3390/f11060700.

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In this study the properties of plywood manufactured from densified and non-densified veneer sheets and alternate layers of such veneers with and without densification using low amount of adhesive as a function of densification temperature and wood species were investigated. The plywood panels were made from rotary-cut birch and black alder veneers using urea-formaldehyde (UF) adhesive. Veneer sheets with thickness of 1.5 mm were subjected to the thermal-compression at three different temperatures while keeping constant the pressure during a same time span. Five-layers plywood panels were produced using a constant hot-pressing schedule using different amounts of glue spread as a function of the plywood type; such as plywood made from non-densified (80 g/m2) and densified (60 g/m2) veneers only; and combination of them (70 g/m2). The bending strength (MOR) and the modulus of elasticity (MOE) along with the shear strength of the plywood samples for bonding class 1 (dry conditions) have been determined. As expected bending strength of the plywood samples increased with the increasing in density. The increase of veneer densification temperature resulted in a gradually decrease of MOR; MOE and shear strength values for the plywood panels made of densified veneers and mixed panels of both species. The temperature of 150 °C for veneer densification seemed to be enough to achieve enhanced bending and bonding properties. All plywood panels in this study were manufactured using reduced glue consumption and they presented satisfactory properties performance for indoor applications.

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Pelit, Huseyin, and Fatih Emiroglu. "Effect of Water Repellents on Hygroscopicity and Dimensional Stability of Densified Fir and Aspen Woods." Drvna industrija 71, no. 1 (March 16, 2020): 29–40. http://dx.doi.org/10.5552/drvind.2020.1901.

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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 %.

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32

Shao, Yali, Lili Li, Zhangjing Chen, Sunguo Wang, and Ximing Wang. "Effects of thermo-hydro-mechanical treatments on various physical and mechanical properties of poplar (Populus) wood." BioResources 15, no. 4 (October 29, 2020): 9596–610. http://dx.doi.org/10.15376/biores.15.4.9596-9610.

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Poplar (Populus) wood was subjected in this work to thermo-hydro-mechanical treatment. The influence of the treatment parameters on the physical and mechanical properties were investigated. The wood samples were densified under three compression ratios (0%, 30%, and 50%), and thermally treated at three temperatures (180 °C, 200 °C, and 220 °C), at three thermal treatment durations (3 h, 4 h, and 5 h). The density, modulus of elasticity, modulus of rupture, radial hardness, and thickness swelling were measured. The results showed that the densities of the samples increased by 36.6% to 49.7%. As the compression rate increased, the temperature, duration, modulus of elasticity, modulus of rupture, and hardness increased. However, the dimensions of the densified samples were less stable. Compared to the densiﬁed samples, the maximum thickness swelling could be reduced by 74% (from 29.7% to 7.8%) when subjected to a thermal treatment at 220 °C for 3 h.

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33

Blomberg, Jonas, and Bengt Persson. "Swelling pressure of semi-isostatically densified wood under different mechanical restraints." Wood Science and Technology 41, no. 5 (November 21, 2006): 401–15. http://dx.doi.org/10.1007/s00226-006-0118-1.

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34

Wei, Jinguang, Fei Rao, Yahui Zhang, Wenji Yu, Chung Hse, and Todd Shupe. "Laminating wood fiber mats into a densified material with high performance." Materials Letters 253 (October 2019): 358–61. http://dx.doi.org/10.1016/j.matlet.2019.06.097.

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35

Porteiro, J., E. Granada, J. Collazo, D. Patiño, and J. C. Morán. "A Model for the Combustion of Large Particles of Densified Wood." Energy & Fuels 21, no. 6 (November 2007): 3151–59. http://dx.doi.org/10.1021/ef0701891.

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36

Hill, Callum A. S., James Ramsay, Barbara Keating, Kristiina Laine, Lauri Rautkari, Mark Hughes, and Bastien Constant. "The water vapour sorption properties of thermally modified and densified wood." Journal of Materials Science 47, no. 7 (December 6, 2011): 3191–97. http://dx.doi.org/10.1007/s10853-011-6154-8.

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37

Kutnar, Andreja, Frederick A. Kamke, and Milan Sernek. "The mechanical properties of densified VTC wood relevant for structural composites." Holz als Roh- und Werkstoff 66, no. 6 (July 15, 2008): 439–46. http://dx.doi.org/10.1007/s00107-008-0259-z.

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38

Liu, Sai, Chi Yan Tso, Hau Him Lee, Yu Wei Du, Kin Man Yu, Shien-Ping Feng, and Baoling Huang. "Self-Densified Optically Transparent VO2 Thermochromic Wood Film for Smart Windows." ACS Applied Materials & Interfaces 13, no. 19 (May 10, 2021): 22495–504. http://dx.doi.org/10.1021/acsami.1c03803.

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39

Lee, Jun Sian, Shahab Sokhansanj, C. Jim Lim, Anthony Lau, and Tony Bi. "Comparative Analysis of Sorption Isotherms for Wood Pellets and Solid Wood." Applied Engineering in Agriculture 35, no. 4 (2019): 475–79. http://dx.doi.org/10.13031/aea.13238.

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Abstract.The published data on equilibrium moisture content vs. equilibrium relative humidity (EMC-ERH) for wood pellet do not cover the range of temperature and relative humidity to which a pellet is exposed to during its storage and handling. A few published EMC-ERH relations covering a wider range of temperatures and relative humidity are available for solid wood (lumber) and wood chips. The question is whether the data for solid wood is applicable to wood pellets. For this research, we examined the sorption isotherms of wood pellets and solid wood. The analysis shows that EMC for solid wood is higher than the EMC for wood pellet for a relative humidity larger than 30%. The slope of EMC-ERH isotherm for solid wood in the range of 30%-70% is slightly steeper than the slope of isotherm for wood pellet, indicating the pellet’s EMC is less sensitive to ERH when compared to EMC-ERH for solid wood. Keywords: EMC, ERH, Densified biomass, Equilibrium moisture content, Equilibrium relative humidity, Solid wood, Wood pellets.

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40

Kutnar, Andreja, Dick Sandberg, and Peer Haller. "Compressed and moulded wood from processing to products." Holzforschung 69, no. 7 (September 1, 2015): 885–97. http://dx.doi.org/10.1515/hf-2014-0187.

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Abstract This paper presents the state of the art of different wood densification processes as one emerging process technology. The main principles for the processes are discussed, such as bulk and surface densification, bending, moulding of shells and tubes, as well as methods for reducing the shape memory effect of densified wood. The main challenges are in the field of scaling up to industrial applications. To provide a better understanding with this regard, some relevant scientific results are presented. Furthermore, the discussion considers the contribution of thermo-hydro and thermo-hydro-mechanical processes to a sustainable and low-carbon economy.

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41

Rutiaga-Quiñones, José Guadalupe, Luis Fernando Pintor-Ibarra, Rocio Orihuela-Equihua, Nicolás González-Ortega, María Alejandra Ramírez-Ramírez, Artemio Carillo-Parra, Noel Carrillo-Ávila, et al. "Characterization of Mexican waste biomass relative to energy generation." BioResources 15, no. 4 (September 23, 2020): 8529–53. http://dx.doi.org/10.15376/biores.15.4.8529-8553.

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In this work, physical and chemical analyses of 28 sawdust samples (tropical woods, pine woods, and oak woods) derived from the primary process of wood transformation and 4 samples of citrus residues were performed, as an option to make densified biofuels. The study included the determination of initial moisture, particle size distribution, proximate analysis, ultimate analysis, calculation of the calorific value, and ash microanalysis. The initial moisture content of the biomass samples ranged from 6.04 to 75.21%. The biomass granulometry results indicate that the highest proportion corresponds to the 1.0-mm (33.10%) (Fraction retained in mesh 0.5 mm). Other results obtained indicate the following ranges: ash content (0.27 to 6.27%), volatile matter (78.90 to 90.50%), fixed carbon (9.10 to 20.44%), carbon (49.13 to 50.78%), oxygen (42.62 to 44.49%), and hydrogen (5.24 to 6.55%). The calculated calorific value ranged from 17.65 MJ/kg to 20.72 MJ/kg. The chemical elements with the highest concentration in the biomass samples were K and Ca, followed in some cases by Al and P. The biomass with the greatest possibilities for making densified biofuels of better quality is the group of pine woods because they have low mineral content, low nitrogen content, and high calorific value.

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42

Zhou, Qiaofang, Chuanfu Chen, Dengyun Tu, Zhipeng Zhu, and Kaifu Li. "Surface densification of poplar solid wood: Effects of the process parameters on the density profile and hardness." BioResources 14, no. 2 (April 30, 2019): 4814–31. http://dx.doi.org/10.15376/biores.14.2.4814-4831.

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Poplar (Populus tomentosa Carr.) solid wood was surface densified in the tangential direction, and the vertical density profile (VDP) and hardness of the treated and untreated samples were measured. The effects of the process parameters on the VDP and hardness were investigated. To explicitly describe the VDP of the surface densified wood, five indices (AD, ADx, PD, PDi, and DTh) were used. The compressing temperature and closing speed influenced the formation and shape of the VDP. A higher temperature yielded a greater PD and Pdi, and a faster closing speed yielded a higher PD, but smaller PDi and DTh. Increasing the compression ratio increased the AD, ADx, and maximum load, and the poplar wood was compressed in the overall thickness as the compression ratio exceeded a certain degree. The Janka hardness of the poplar wood was significantly improved after surface densification; a higher temperature resulting in a higher surface hardness was explained by the higher PD. The closing speed and compression ratio affected the hardness by impacting the VDP, specifically the PD and DTh indices. When the PD and DTh were greater the surface hardness was greater. By this study, a compressing temperature of 140 to 160 °C and the closing speed of 10 mm/min is recommended, and to prevent the deformation of unheated side of the wood samples and obtain a higher surface hardness, the compression ratio is restricted to 20%.

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43

Fu, Qilan, Alain Cloutier, Aziz Laghdir, and Tatjana Stevanovic. "Surface Chemical Changes of Sugar Maple Wood Induced by Thermo-Hygromechanical (THM) Treatment." Materials 12, no. 12 (June 17, 2019): 1946. http://dx.doi.org/10.3390/ma12121946.

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The aim of this study was to investigate the effects of heat and steam on the chemical properties of thermo-hygromechanical (THM)-densified sugar maple wood. The THM densification process was performed at two different temperatures (180 °C and 200 °C) with and without steam. The functional groups, surface chemical composition and internal structure and components of the control and densified samples were investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray photoelectron (XPS) spectroscopy and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The obtained results suggest that the THM densification treatment resulted in significant chemical changes on the wood surface. The results of the ATR-FTIR spectra confirmed the decomposition of hemicelluloses and the relative increase of cellulose and lignin contents on the wood surface. The Py-GC/MS and XPS results show an increase of the oxygen/carbon atomic (O/C) ratio, which indicated that chemical substances containing oxygenated functionality were formed through the densification process. The densification treatment favored the depolymerization of hemicelluloses and cellulose as indicated by an increased anhydrous sugar (levoglucosan) release during the pyrolysis process. Densification also facilitated the cleavage of the lignin side chains, resulting in increased phenyl units with short chains released during the pyrolysis process.

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44

Budakçı, Mehmet, Süleyman Şenol, and Mustafa Korkmaz. "Effects of Thermo-Vibro-Mechanic® densification on the density and swelling of pre-treated Uludağ fir and black poplar wood." BioResources 16, no. 1 (January 13, 2021): 1581–99. http://dx.doi.org/10.15376/biores.16.1.1581-1599.

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The radial and tangential swelling as well as the fully dried density of low-density wood materials densified via the Thermo-Vibro-Mechanic® method were evaluated in response to applying wood stain and preservative. The samples obtained from Uludağ fir (Abies bornmüelleriana Mattf.) and black poplar (Populus nigra L.) in the radial and tangential direction were pre-treated with wood stain and preservative before undergoing Thermo-Vibro-Mechanic® densification. Thermo-Vibro-Mechanic® densification was performed at three different temperatures (100 °C ± 3 °C, 120 °C ± 3 °C, and 140 °C ± 3 °C), three different vibration pressures (0.60 MPa, 1.00 MPa, and 1.40 MPa), and three different vibration times (20 s, 60 s, and 100 s). Afterwards, changes in the fully dried density and swelling amounts in the radial and tangential directions of the samples were determined. The fully dried density increased by 15.4% to 38% and the radial and tangential swelling amounts increased by 73.2% to 242.6%, when the densified samples were compared to the control samples. In general, the fully dried density and swelling values increased depending on the Thermo-Vibro-Mechanic® densification parameters; higher values were found as the compression ratio and total application time increased.

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45

Laine, K., T. Antikainen, L. Rautkari, and M. Hughes. "Analysing density profile characteristics of surface densified solid wood using computational approach." International Wood Products Journal 4, no. 3 (August 2013): 144–49. http://dx.doi.org/10.1179/2042645313y.0000000031.

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46

Collazo, J., J. Porteiro, D. Patiño, and E. Granada. "Numerical modeling of the combustion of densified wood under fixed-bed conditions." Fuel 93 (March 2012): 149–59. http://dx.doi.org/10.1016/j.fuel.2011.09.044.

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47

Rassam, Ghonche, Mohammad Ghofrani, Hamid Reza Taghiyari, Behnam Jamnani, and Mohamad Ali Khajeh. "Mechanical performance and dimensional stability of nano-silver impregnated densified spruce wood." European Journal of Wood and Wood Products 70, no. 5 (November 26, 2011): 595–600. http://dx.doi.org/10.1007/s00107-011-0590-7.

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48

Bekhta, Pavlo, Stanisław Proszyk, and Tomasz Krystofiak. "Colour in short-term thermo-mechanically densified veneer of various wood species." European Journal of Wood and Wood Products 72, no. 6 (September 5, 2014): 785–97. http://dx.doi.org/10.1007/s00107-014-0837-1.

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49

Zhan, Jian-feng, and Stavros Avramidis. "Transversal mechanical properties of surface-densified and hydrothermally modified needle fir wood." Wood Science and Technology 51, no. 4 (April 17, 2017): 721–38. http://dx.doi.org/10.1007/s00226-017-0909-6.

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50

Sikora, Adam, Milan Gaff, Anil Kumar Sethy, Nicholas Fantuzzi, and Petr Horáček. "Bending work of laminated materials based on densified wood and reinforcing components." Composite Structures 274 (October 2021): 114319. http://dx.doi.org/10.1016/j.compstruct.2021.114319.

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Journal articles on the topic 'Densified wood'

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