Journal articles: 'Thermo-wood'

1

Birkinshaw, C., M. Buggy, and A. Carew. "Thermo-mechanical behaviour of wood and wood products." Journal of Materials Science 24, no. 1 (January 1989): 359–62. http://dx.doi.org/10.1007/bf00660981.

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Laskowska, Agnieszka. "Impact of cyclic densification on bending strength and modulus of elasticity of wood from temperate and tropical zones." BioResources 15, no. 2 (March 9, 2020): 2869–81. http://dx.doi.org/10.15376/biores.15.2.2869-2881.

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Oak (Quercus robur L.), iroko (Milicia excelsa (Welw.) C.C. Berg), and tauari (Couratari spp.) wood were subjected to cyclic thermo-mechanical treatment (CTMT). The densification temperature amounted to 100 °C or 150 °C. The greatest changes in the modulus of rupture (MOR) value of the iroko wood, depending on the number of thermo-mechanical modification cycles, were noted. The MOR of the iroko wood, densified at 100 °C or 150 °C, after second thermo-mechanical modification cycle was twice as high as before the modification. No significant differences were observed between the modulus of elasticity (MOE) of oak wood before and after one modification cycle. Similar dependencies were noted in iroko wood. The thermo-mechanical modification performed over two cycles led to the highest increase, by about 56%, in MOE in oak wood densified at 150 °C. It was demonstrated that modification at 150 °C had a negative impact on iroko wood, which was manifested in the lower compression ratio of iroko at 150 °C than at 100 °C.

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Sandberg, Dick, Peer Haller, and Parviz Navi. "Thermo-hydro and thermo-hydro-mechanical wood processing: An opportunity for future environmentally friendly wood products." Wood Material Science and Engineering 8, no. 1 (March 2013): 64–88. http://dx.doi.org/10.1080/17480272.2012.751935.

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Chen, Hongyan, Mohsen Bahmani, Miha Humar, and Dali Cheng. "Properties of Wood Ceramics Prepared from Thermo-Modified Poplar." Forests 11, no. 11 (November 16, 2020): 1204. http://dx.doi.org/10.3390/f11111204.

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Wood ceramics (WCS) were prepared from thermo-modified poplar wood residues and untreated poplar wood. At 1000 °C sintering temperature, the ratios of wood powder and phenolic resin at 10:3, 10:6 and 10:9 were tested. The effects of materials on the properties of WCS, carbon yield and volume shrinkage were studied. With the increase in resin content, the carbon yield increased; however, the volume shrinkage decreased. Carbon yield of WCS made from 220 °C thermo-modified poplar wood was 40.45%, as the ratio of wood powder/phenolic resins was 10:6. The microstructure, chemical structure and crystallinity of WCS were analysed by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and X-ray diffraction (XRD), respectively. The results showed that WCS had a porous structure. WCS prepared from thermo-modified materials, amorphous carbon and hard glass carbon melted more evenly; meanwhile, there were more pores on glass carbon. The FTIR spectra showed that the stretching vibration of C-O-C weakened at ceramics made of thermo-modified poplar. The XRD pattern indicated that the raw material has no apparent influence on the graphitization degree of WCS.

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Fleischhauer, Robert, Jens U. Hartig, Peer Haller, and Michael Kaliske. "Moisture-dependent thermo-mechanical constitutive modeling of wood." Engineering Computations 36, no. 1 (November 19, 2018): 2–24. http://dx.doi.org/10.1108/ec-09-2017-0368.

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PurposeThe purpose of this study is the numerical investigation of densification and molding processes of wood. Providing theoretical and numerical approaches with respect to a consistent multi-physical finite element method framework are further goals of this research.Design/methodology/approachConstitutive phenomenological descriptions of the thermo-mechanical and moisture-dependent material characteristics of wood are introduced. Special focus is given to a consistent hygro-thermo-mechanical modeling at finite deformations to capture the realistic material behavior of wood, especially when it is subjected to densification and molding processes.FindingsRealistic theoretical formulations of different hygro-thermo-mechanical processes are provided. A successful numerical modeling is demonstrated for beech wood by validation at experimental findings.Originality/valueThe constitutive laws and numerical findings are new, as they govern a multi-physical large deformation framework and are applied to the advanced technology of densification and molding of 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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Khezami, Lotfi, Aissa Ould-Dris, and Richard Capart. "Activated carbon from thermo-compressed wood and other lignocellulosic precursors." BioResources 2, no. 2 (April 15, 2007): 193–209. http://dx.doi.org/10.15376/biores.2.2.193-209.

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The effects of thermo-compression on the physical properties such as bulk density, mass yield, surface area, and also adsorption capacity of activated carbon were studied. The activated carbon samples were prepared from thermo-compressed and virgin fir-wood by two methods, a physical activation with CO2 and a chemical activation with KOH. A preliminary thermo-compression method seems an easy way to confer to a tender wood a bulk density almost three times larger than its initial density. Thermo-compression increased yield regardless of the mode of activation. The physical activation caused structural alteration, which enhanced the enlargement of micropores and even their degradation, leading to the formation of mesopores. Chemical activation conferred to activated carbon a heterogeneous and exclusively microporous nature. Moreover, when coupled to chemical activation, thermo-compression resulted in a satisfactory yield (23%), a high surface area (>1700 m2.g-1), and a good adsorption capacity for two model pollutants in aqueous solution: methylene blue and phenol. Activated carbon prepared from thermo-compressed wood exhibited a higher adsorption capacity for both the pollutants than did a commercial activated carbon.

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Tabari, Hassan Ziaei, Fateme Rafiee, Habibolah Khademi-Eslam, and Mohammad Pourbakhsh. "Thermo-Chemical Evaluation of Wood Plastic Nanocomposite." Advanced Materials Research 463-464 (February 2012): 565–69. http://dx.doi.org/10.4028/www.scientific.net/amr.463-464.565.

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Most applications expose the materials to wide range of temperatures, which may influence on thermal behavior of materials. Thermal degradation of wood polymer composites (WPCs) is a crucial aspect for application and manufacturing process of these products. In this research, wood polymer composites with different nanoclay contents were prepared by melts compounding method. The amount of wood flour and coupling agent were fixed at 40% and 10% wt% (total weight), respectively, and the different levels of nanoclay include 0, 3 and 5% wt% were used in preparing the composites. Thermal properties of nanocomposites were characterized by Differential Scanning Calorimeter (DSC) and thermal gravimetric analysis (TGA). The DSC analyses show that the crystallization temperature (Tc), enthalpy ΔHm, and the degree of crystallinity (Xc) of the nanocomposites were increased by addition of nanoclay. The TGA results indicate that by increasing the nanoclay percentage the degradation temperatures and thermal stability was enhanced.

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de Lima, Nídia Niela, Vinícius Resende de Castro, Nayara Franzini Lopes, Ítalo Lima Nunes, Frances Alves Andrade, Antonio José Vinha Zanuncio, Angélica de Cassia Oliveira Carneiro, and Solange Araújo. "Tannin extracts as a preservative for pine thermo-mechanically densified wood." BioResources 18, no. 1 (November 22, 2022): 641–52. http://dx.doi.org/10.15376/biores.18.1.641-652.

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Thermo-mechanical densification modifies wood to produce a more dense and resistant lignocellulosic material and may degrade extractives that contribute to the increased susceptibility of wood to attack by xylophagous organisms. This study evaluated the efficiency of tannin extracts of Acacia mearnsii in the treatment of thermo-mechanical densified pine wood in relation to physical, mechanical, and biological resistance (Cryptotermes brevis) properties. Pinus elliottii samples were pretreated with oxalic acid in a Parr reactor, then treated by diffusion in tannin solutions at concentrations 5, 10, and 15%, and finally hot pressed. The apparent density of the modified wood was 87.8% greater than that of the in natura wood (control) with tannins at 15%. The mechanical strength increased, especially the parallel compressive strength, which had an average increase of 169% for the wood with tannins at 10 and 15%, compared with the in natura wood. There was an increase in termite mortality and a reduction in damage for the modified wood treated with 15% tannins, obtaining the best results in mechanical and biological resistance and for the physical parameters. Thermal densification pine wood and preserved with tannin extractives proved to be a potential alternative as a high performance material.

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Tuyen, Nguyen Thi, Pham Van Chuong, and Vu Kim Dung, al. et. "Resistance of Cunninghamia lanceolata Wood Against White-rot Fungi by Using Thermo-Mechanical Treatment." Journal of Agriculture and Crops, no. 92 (March 1, 2023): 178–86. http://dx.doi.org/10.32861/jac.92.178.186.

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Heat treatment is an effective method to enhance the biological durability of wood without the use of preservatives. This study aims to analyze the effect of thermo-mechanical treatment on the durability of wood against the attack of some white rot fungi. The central composite design (CCD) method with the help of Design Expert 12.0 software was used to investigate the effects of temperature, compression time, and compression ratio on the white rot fungus resistance of Cunninghamia lanceolata wood. The obtained results revealed that the thermo-mechanical treatment of Cunninghamia lanceolata samples showed improved antifungal resistance compared to the untreated ones. After 4 months of testing in laboratory conditions, all wood samples with heat-mechanical treatment showed better resistance to fungi. Moreover, the different temperatures, compression ratios, and compression time bring out the different mass loss rates. The obtained results indicate that the wood samples modified at the temperature of 200°C, and 0.6 min/mm thickness combined with the compression ratio ranging from 40÷42% gave the lowest loss rate. Particularly, the resistance test for Lentinula edodes gives the best results when the wood compression time is at 0.7 min/mm thickness. Also, this work would provide a scientific and theoretical basis for the relationship between thermo-mechanical treatment and the biological durability of Cunninghamia lanceolata wood.

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11

Sun, De Lin, Xian Chun Yu, De Bin Sun, and Rong Wang. "Woodceramics Prepared form Liquefaction Wood and Wood Powder." Applied Mechanics and Materials 190-191 (July 2012): 585–89. http://dx.doi.org/10.4028/www.scientific.net/amm.190-191.585.

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A woodceramics makes from liquefaction wood and wood powder, the basic property connects with sintering temperature and liquefaction wood content. Thermo gravimetric analysis indicates that higher liquefaction wood content lead to reduce the weight loss. Scanning electron microscopy observation shows that wood powder is as a natural plant template and the basic structure of wood can partly keep. The apparent density increases before about 1100°C, and then decreases as temperature gets further; but the apparent porosity increases continuous; bending strength increases from 8.45 MPa to 11.87 MPa when the liquefaction wood content raises 60%-120%. Meanwhile, elevation of liquefaction wood content and sintering temperature can reduce abrasion loss.

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12

Zheng, Qingzhu, Weifeng Zhang, Huiping Lin, Junwen Yu, Wenbin Yang, and Xinxiang Zhang. "Plasma Treatments to Improve the Bonding of Thermo-Treated Cherry Wood." Coatings 9, no. 10 (October 11, 2019): 656. http://dx.doi.org/10.3390/coatings9100656.

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Thermal treatment can significantly improve the dimensional stability of wood, but it will decrease the bonding strength. In this work, the bonding strength of thermo-treated cherry wood boards was improved by plasma treatment. The change of wettability, surface morphology, and surface chemical property of cherry wood before and after plasma treatment was investigated by water contact angle measurement, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The plasma treatment significantly improved the wettability of thermo-treated cherry wood by decreasing its water contact angle from 109.95° to 53.18°. N2 or O2 was used as the plasma atmosphere, and it was found that N2 plasma treatment afforded cherry wood a rougher surface. The AFM roughness of cherry wood was increased from 19 nm to 31.9 nm after N2 plasma treatment. XPS results revealed an additional C–N group for N2 plasma treatment and the content of C=O, O–C–O, and O–C=O increased for O2 plasma treatment, respectively, indicating that the surface chemical property of cherry wood was modified. Due to the surface character, the bonding strength increased by 21.17% for N2 plasma treatment and 15.32% for O2 plasma treatment.

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13

Budakçı, Mehmet, Süleyman Şenol, and Mustafa Korkmaz. "Thermo-Vibro-Mechanic® (TVM) wood densification method: Mechanical properties." BioResources 17, no. 1 (January 14, 2022): 1606–26. http://dx.doi.org/10.15376/biores.17.1.1606-1626.

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A densification method is proposed and developed to improve the mechanical properties of Uludağ fir (Abies bornmüelleriana Mattf.) and black poplar (Populus nigra L.) woods. The method, called Thermo-Vibro-Mechanic® densification, is derived from the hypothesis that the vibration added to the traditional thermo-mechanical densification process can cause the wood cell walls to interlock with each other at the micro-level via the friction effect. In addition, it aims to remove the cell cavities under lower pressure compared to other densification methods via the shaking effect. To test this hypothesis, the samples, obtained in both the radial and tangential directions, were pre-treated with wood stain and preservative before undergoing the densification process. Thermo-Vibro-Mechanic® densification was performed at varying temperatures (100, 120, and 140 °C), pressures (0.60, 1.00, and 1.40 MPa), and durations (20, 60, and 100 s). The changes in the values of the bending strength, modulus of elasticity, and compression strength parallel to the grain in the radial and tangential directions were determined accordingly. The results showed that the Thermo-Vibro-Mechanic® densification process increased the bending strength and modulus of elasticity values up to 50%, while the compression strength reached 67% higher than the untreated wood.

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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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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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He, Zaixin, Yanran Qi, Gang Zhang, Yueying Zhao, Yong Dai, Baoxuan Liu, Chenglong Lian, Xiaoying Dong, and Yongfeng Li. "Mechanical Properties and Dimensional Stability of Poplar Wood Modified by Pre-Compression and Post-Vacuum-Thermo Treatments." Polymers 14, no. 8 (April 12, 2022): 1571. http://dx.doi.org/10.3390/polym14081571.

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Fast-growing poplar wood has the bottleneck problems of inferior mechanical strength and poor dimensional stability. In this study, the wood was modified by combined treatments of pre-compression and post-vacuum-thermo modification to improve its mechanical strength and dimensional stability, simultaneously; in addition, the variation law of mechanical properties of the wood with compression ratio as well as the improvement effect of dimensional stability of the treated wood were mainly studied. The results show that the optimal temperature and time of the vacuum-thermo modification were 190 °C and 10 h, respectively. Under these conditions, the structure of pre-compressed and post-vacuum-thermally modified wood (CT wood) is gradually densified with the increase in the compression ratio, which results in the continuous enhancement of mechanical properties. Meanwhile, the anti-swelling efficiency (ASE) of the CT wood after water absorption is correspondingly better than that of the compressed wood before thermal modification, indicating that the dimensional stability of compressed wood was improved by the thermal modification. When the compression ratio was 70%, the modulus of rupture (MOR) and impact toughness of CT wood was 176 MPa and 63 KJ/m2, which was 125% and 59% higher than that of untreated wood, respectively. The ASE was also 26% higher than that of the wood with sole compression. Therefore, this method improves the mechanical strength and dimensional stability of wood simultaneously, and it provides a scientific basis for optimization of the reinforcing modification process of fast-growing wood.

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Laskowska, Agnieszka, Monika Marchwicka, Agata Trzaska, and Piotr Boruszewski. "Surface and Physical Features of Thermo-Mechanically Modified Iroko and Tauari Wood for Flooring Application." Coatings 11, no. 12 (December 12, 2021): 1528. http://dx.doi.org/10.3390/coatings11121528.

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The aim of the study was to determine the selected surface and physical properties of iroko (Milicia excelsa (Welw.) C.C. Berg) and tauari (Couratari spp.) wood after thermo-mechanical treatment (TMT) in relation to extractive content. During TMT, no chemicals are introduced into the wood, which distinguishes this method from a number of wood modification methods. The iroko and tauari wood were subjected to volumetric densification in a hydraulic press. The wood was densified in a radial direction at a temperature of 100 and 150 °C. The wood color parameters were measured using the mathematical CIE L*a*b* and L*C*h color space models. The roughness parameters of Ra and Rz parallel and perpendicular to the grain were investigated. The contact angle (CA) of the wood with distilled water was determined based on the sessile drop method. The equilibrium moisture content (EMC) and dimensional changes of the wood were determined for a climate with a temperature of 20 °C and a relative humidity (RH) of 9%, 34%, 55%, 75% and 98%. The tauari wood was less prone to color changes under the influence of TMT than the iroko wood. After densification, the iroko and tauari wood displayed a different character of roughness changes. The iroko wood featured the lowest level of roughness after TMT at 100 °C, and the tauari wood after TMT at 150 °C. The densified iroko and tauari wood were characterized by weaker dynamics in the changes in their respective contact angles than the non-densified wood. The higher the temperature of the TMT, the lower the EMC of the wood. Higher EMC values were observed for the tauari wood than for the iroko wood. This was due to the lower content of chloroform-ethanol extractives. Similar dependencies were obtained in the case of hot water extractives. The thermo-mechanically treated wood displayed a greater tendency towards dimensional changes in a climate with high relative air humidity, i.e., above 70%, compared to the non-modified wood.

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Mecca, Marisabel, Luigi Todaro, Valentina Lo Giudice, Teresa Lovaglio, and Maurizio D’Auria. "GC-MS and SPME Techniques Highlighted Contrasting Chemical Behaviour in the Water Extractives of Modified Castanea sativa Mill. and Fagus sylvatica L. Wood." Forests 12, no. 8 (July 26, 2021): 986. http://dx.doi.org/10.3390/f12080986.

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The sweet chestnut (Castanea sativa Mill.) and European beech (Fagus sylvatica L.) are wood species largely present in the European forest area. The composition and relative variation of the secondary metabolites of chestnut and European beech wood under thermal effect is a little-explored area. The wood material was thermally modified at 170 °C for 3 h using a thermo-vacuum technology. Raw and modified wood extracts were obtained with aqueous extraction techniques in an autoclave, subsequently lyophilized, solubilized in ethyl acetate, and determined by Gas Chromatographic-Mass Spectrometric Analyses (GC-MS). In addition, the volatile compounds were determined by Solid-Phase Micro Extraction (SPME) analyses. As a general statement, the extraction in an autoclave produced a higher number of compounds in the modified chestnut and beech wood compared to unmodified wood material. Beech wood showed low degradation in the compounds after modification. Notably, squalene and ar-tumerone were the main bioactive compounds present in beech wood extractives. Chestnut, conversely, showed a greater degradation after thermo-modification. However, a reduction in chemical compounds in the modified samples was also observed. In this case, the main biologically active compounds detected only in the chestnut control samples were apocynin and ar-tumerone. The recovery of this residual wood material, before energy consumption, could provide a sustainable and environmentally friendly means of obtaining natural chemicals suitable for various industrial applications.

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Navi, Parviz, and Frédéric Heger. "Combined Densification and Thermo-Hydro-Mechanical Processing of Wood." MRS Bulletin 29, no. 5 (May 2004): 332–36. http://dx.doi.org/10.1557/mrs2004.100.

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AbstractThe process of heating and compressing wood to improve its properties or reform it to a new shape has been known for decades. Such improvements are usually accompanied by “shape memory,” where the deformation produced by compression is not permanent, and the material recovers when re-moistened and heated. The combination of densification and a thermo-hydro-mechanical (THM) treatment can transform wood into a new material with improved mechanical properties, decreased sensitivity to moisture, increased durability, and no shape-memory effects. This article presents the principles of combined densification and THM processing, the products and experimental results, the origin of the shape-memory effect and its elimination by THM treatment, and the potential use of THM-processed densified wood in construction applications.

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Goldšteins, Linards, Māris Gunārs Dzenis, Raimonds Valdmanis, Maija Zaķe, and Alexandr Arshanitsa. "Thermo-Chemical Conversion of Microwave Selectively Pre-Treated Biomass Blends." Energies 15, no. 3 (January 20, 2022): 755. http://dx.doi.org/10.3390/en15030755.

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Possibilities of more efficient use of regional lignocellulosic resources (wood, wheat straw, peat) of different origin for an environmentally friendly energy production using selectively MW pre-treated blends of commercial wood or wheat straw pellets with raw peat pellets are studied. A hypothesis is proposed and tested that selective MW pre-treatment of wood or wheat straw pellets at the frequency 2.45 GHz and blending of MW pre-treated pellets with raw peat pellets can be used to enhance and control the thermo-chemical conversion of biomass blends. To test this hypothesis, a combined experimental study and mathematical modelling of the processes were performed. The thermo-chemical conversion of selectively activated blends was experimentally studied using a batch-size pilot device, which consists of a biomass gasifier and a combustor. To evaluate the effect of selective MW pre-treatment of biomass pellets on the thermo-chemical conversion of pre-treated blends, measurements of the kinetics of weight loss, yield of combustible volatiles, flame temperature, heat output of the device, and composition of emissions were made at different MW pre-treatment regimes of wheat straw and wood pellets and different mass fractions of pre-treated pellets in biomass blends. The developed novel 2D numerical model of thermo-chemical conversion of MW pre-treated straw confirmed that the pre-treatment of wheat straw pellets increases the generated heat and significantly affects the temperature distribution in the flame/bed zones. It was confirmed that MW pre-treatment leads to a faster thermal decomposition of biomass pellets, synergistically activating the non-treated parts of blends. The overall improved yield of combustible volatiles and their complete combustion provide a surplus of heat production by limiting the formation of GHG emissions, which allows promoting MW pre-treated biomass of different origin as efficient regional bioenergy resources for energy production.

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Fu, Qilan, Xiang-Ming Wang, Alain Cloutier, and Fabrice Roussière. "Chemical characteristics of thermo-hydrolytically recycled particles." BioResources 15, no. 2 (April 3, 2020): 3774–86. http://dx.doi.org/10.15376/biores.15.2.3774-3786.

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Particles from waste laminated particleboards were recovered using various thermo-hydrolytic treatments. The size distribution and three main chemical properties, such as pH, buffer capacity, and nitrogen content of the control and resulting particles were determined. The effects of treatment temperature and duration on the chemical properties of recycled particles were investigated. The effects of the resulting particles on the gel time of urea-formaldehyde (UF) resin were also measured. The test results suggested that the pH of particles after hot water soaking pre-treatment and the different thermo-hydrolytic treatments increased to different extents, with the exception of the particles treated at 140 °C for 50 min and 160 °C for 20 min. The acid buffer capacity and base buffer capacity of particles treated at 140 °C for 50 min and 160 °C for 20 min had no statistical difference, but they were much higher than those of other types of treated particles. A high treatment temperature facilitated the decomposition of wood polymers and UF resin. Both temperature and treatment duration had significant effects on pH, acid buffer capacity, and base buffer capacity of wood particles. Wood particles recycled at a high temperature had a negative effect on the gel time of UF resin.

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Pockrandt, Michael, Mohamed Jebrane, Ignazia Cuccui, Ottaviano Allegretti, Ernesto Uetimane, and Nasko Terziev. "Industrial Thermowood® and Termovuoto thermal modification of two hardwoods from Mozambique." Holzforschung 72, no. 8 (July 26, 2018): 701–9. http://dx.doi.org/10.1515/hf-2017-0153.

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AbstractThe study aimed at treating metil (Sterculia appendiculataK. Schum) and neem (Azadirachta indicaA. Juss) timber from Mozambique under industrial conditions by steam [Thermowood®(TW)] and vacuum [Termovuoto (TV)] thermal modifications (TM). Matched boards were treated identically and wood alterations in chemistry, colour, mass loss (ML), mechanical properties and durability were compared. The applied vacuum partly removed the acetic acid that causes carbohydrate degradation, i.e. heat applied under vacuum was less destructive. TM under vacuum generated a lighter colour than that caused by steam treatment. ML was significantly higher after the TW process namely, 14.1 vs. 9.9% after thermo-vacuum treatment for metil and 14.2 and 12.1% for neem. Colour and ML changes correlated with the decrease in shear strength, rupture and elasticity moduli and increase in wood decay resistance. Metil wood is more permeable and demonstrated significant differences between the treatments; the thermo-vacuum process was less destructive but led to less improvement of durability compared to TW treatment.

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Zashchepkina, N. M., O. V. PROKOPOVICH, and D. S. MAKARENKO. "Thermal modification of wood by the method of thermo-mechanical dehydration with pressure drop." Annals of WULS, Forestry and Wood Technology 106 (January 15, 2019): 128–33. http://dx.doi.org/10.5604/01.3001.0013.7748.

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Thermal Modification of Wood by the Method of Thermo-Mechanical Dehydration with Pressure Drop. The results of experimental research of thermal wood processing by the method of high temperature drying with pressure drop are presented. Drying was carried out cyclically by heating the material under pressure to the temperature 100-140 oC followed by pressure drop. After that the temperature was raised up 160-210 oC and the samples were processed briefly in those conditions. This treatment is shown to be effective for largesized wood.

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Kumar, Manoj, P. L. Sah, M. G. H. Zaidi, and Anupam Srivastav. "Thermal Characterization of Low Grade Wood Polyacylonitrile Composite." Advanced Materials Research 214 (February 2011): 392–96. http://dx.doi.org/10.4028/www.scientific.net/amr.214.392.

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A series of wood polyacrylonitrile (PAN) composites (WPCs) were synthesized through impregnation polymerization of Eucalyptus wood (Eucalyptus Grandies) by acrylonitrile (AN) in methanol (20-60% v/v) in the presence of benzoyl peroxide (1.0% w/v) in benzene medium at 70 ±10C. This resulted in corresponding WPCs with polyacrylonitrile (PAN) loading in the range of 15.5-20%. Loading of PAN into wood, as ascertained through TGA, DTGA and DTA and supported by Fourier Transform Infrared Spectroscopy (FTIR) as well as Scanning Electron Microscopy (SEM) was found to increase the resistance against thermo-oxidation of WPCs in comparison to untreated wood.

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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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Navi, Parviz, and Antonio Pizzi. "Property changes in thermo-hydro-mechanical processing." Holzforschung 69, no. 7 (September 1, 2015): 863–73. http://dx.doi.org/10.1515/hf-2014-0198.

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Abstract Thermo-hydro-mechanical (THM) treatment is a combined action of temperature, moisture, and mechanical force, which leads to modified wood (THMW). Various types of eco-friendly THM processes have been developed to enhance wood properties and generate new materials, such as welding, densification, molding, bending, profiling, artificial aging, panel manufacture, and surface densification. The various transformation processes in the course of THM bring about positive effects in terms of the mechanical and physical properties as well as the biological durability. To the negative effects belong the loss in strength and fracture toughness, and one of the challenges is to minimize these negative aspects. The present paper reviews the chemical transformations processes during THM treatment in a closed processing system and presents the relationship between processing parameters and THMW properties. The discussion includes the problems associated with eliminating the set recovery of densified wood by THM posttreatments and the chemical origin of the relaxation of internal stresses induced by densification.

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Cai, Chenyang, Henrik Heräjärvi, and Antti Haapala. "Effects of environmental conditions on physical and mechanical properties of thermally modified wood." Canadian Journal of Forest Research 49, no. 11 (November 2019): 1434–40. http://dx.doi.org/10.1139/cjfr-2019-0180.

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The behaviour of industrially modified wood has not been systematically evaluated in controlled exposure conditions. The objective of this study was to assess the equilibrium moisture content (EMC), dimensions, and Brinell hardness of thermally modified wood in different conditions of temperature and relative humidity (RH). Tested materials consisted of European ash (Fraxinus excelsior L.), Norway spruce (Picea abies (L.) Karst.), and Scots pine (Pinus sylvestris L.) that were thermally modified according to ThermoWood industrial processes into the classes Thermo-S and Thermo-D. The properties were measured at the following conditions: 20 °C and 65% RH, 10 °C and 90% RH, and 30 °C and 30% RH. The results show that the reduction of EMC and the improvement in dimensional stability are dependent on the degree of thermal modification. Thermal modification was more resistant to moisture absorption at 20 °C and 65% RH than at 10 °C and 90% RH and 30 °C and 30% RH, and the more severe modification decreased the difference among different exposure conditions. The tangential–radial ratio of swelling and shrinkage was higher for thermally modified wood than for nonmodified wood. Brinell hardness of modified Scots pine and Norway spruce did not differ significantly from that of nonmodified wood in normal and dry conditions, but the more humid conditions increased the difference by 12%–17%.

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Rojas Vega, Carlos, Juan Carlos Pina, Emanuela Bosco, Erick I. Saavedra Flores, Carlos F. Guzman, and Sergio J. Yanez. "Thermo-mechanical analysis of wood through an asymptotic homogenisation approach." Construction and Building Materials 315 (January 2022): 125617. http://dx.doi.org/10.1016/j.conbuildmat.2021.125617.

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Knapic, Sofia, Joana Santos, José Santos, and Helena Pereira. "Natural durability assessment of thermo-modified young wood of eucalyptus." Maderas. Ciencia y tecnología, ahead (2018): 0. http://dx.doi.org/10.4067/s0718-221x2018005031801.

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30

Borysiak, Slawomir. "The thermo-oxidative stability and flammability of wood/polypropylene composites." Journal of Thermal Analysis and Calorimetry 119, no. 3 (December 27, 2014): 1955–62. http://dx.doi.org/10.1007/s10973-014-4341-y.

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Nourbakhsh, A., A. Ashori, H. Ziaei Tabari, and F. Rezaei. "Mechanical and thermo-chemical properties of wood-flour/polypropylene blends." Polymer Bulletin 65, no. 7 (May 9, 2010): 691–700. http://dx.doi.org/10.1007/s00289-010-0288-8.

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32

Windeisen, Elisabeth, Claudia Strobel, and Gerd Wegener. "Chemical changes during the production of thermo-treated beech wood." Wood Science and Technology 41, no. 6 (June 13, 2007): 523–36. http://dx.doi.org/10.1007/s00226-007-0146-5.

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33

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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Sultan, Md Tipu, Md Rezaur Rahman, Sinin Hamdan, and Md Faruk Hossen. "Physical, and Thermal Properties of Wood Impregnated with a Mixture of Furfuryl Alcohol, Styrene, and Nanoclay." Materials Science Forum 997 (June 2020): 29–36. http://dx.doi.org/10.4028/www.scientific.net/msf.997.29.

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In this study, raw wood (RW) samples were impregnated with a mixture of furfural alcohol (FA), styrene (ST), and nanoclay of varying concentration of FA and ST. These impregnated wood and RWsamples were then subjected to FTIR, water uptake (WU), and thermal studies. The FT-IR results at 1600-1800 cm-1 showed that the ST/FA/clay-WPNCs had different peak numbers with different positions compared with the RW. So, there was an interaction between RW, FA, ST and clay. The WU of ST/FA/clayimpregnated wood is lower than RW. In thermo gravematric result, below 100 °C the impregnated wood samples had less weight lost compared to RW.

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35

Dömény, Jakub, Martin Brabec, Radim Rousek, Lauri Rautkari, and Petr Čermák. "Effect of microwave and steam treatment on the thermo-hygro-plasticity of beech wood." BioResources 16, no. 4 (October 28, 2021): 8338–52. http://dx.doi.org/10.15376/biores.16.4.8338-8352.

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The effects of microwave and steam treatment were analyzed relative to the immediate (thermo-hygro-plasticity) and post-assessed (permanent changes) properties of wood. The study was conducted using European beech (Fagus sylvatica L.) standard and 1.5 times up-scaled (only for microwave-heated and reference samples) bending specimens tested in a static three-point loading mode. The specimens were plasticized by heat and moisture (1) separately and (2) simultaneously by heating moist specimens using (i) various microwave regimes in continuous mode, and (ii) heated saturated steam in discontinuous mode. Oven-dried specimens tested at 20 °C served as references. The thermo-hygro-plasticity was studied immediately after treatment, whereas the permanent changes were assessed after oven-drying of plasticized specimens to 0% moisture content. Permanent structural changes were analyzed using scanning electron microscopy. Microwave treatment increased the plasticity of wood (decreasing the modulus of elasticity by 70%) comparably to steam treatment, when the output moisture content was 30% or higher. A similar degree of plasticity was found in up-scaled specimens heated by microwaves. Further analyses confirmed that microwave treatment did not cause any permanent damage to wood structure or reduce mechanical performance. The results showed that microwave treatment is an efficient alternative to steaming when plasticizing moist wood.

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Shaikhutdinova, Aigul Ravilevna, Ruslan R. Safin, and Farida V. Nazipova. "Thermal Modification of Wood in Production of Finishing Materials." Solid State Phenomena 265 (September 2017): 171–76. http://dx.doi.org/10.4028/www.scientific.net/ssp.265.171.

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The ways of wood thermal treatment applied in Russia and abroad and the scopes of thermo wood as a construction material are considered in the article. The technology of thermal treatment of high moisture wood with moisture content of 60% in the environment of saturated steam without preliminary drying, developed by authors, is described. The results of the research of the color scale change of oak wood depending on the processing temperature and treatment duration, and also the influence of thermal treatment on the main mechanical properties of thermally modified wood as the finishing material, in particular on the Ra and Rz roughness parameters are presented. As a result of the conducted research the improvement of final physic mechanical and esthetic characteristics of the material after the processing of wood under this technology is proven.

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Lovaglio, Teresa, Wolfgang Gindl-Altmutter, Tillmann Meints, Nicola Moretti, and Luigi Todaro. "Wetting Behavior of Alder (Alnus cordata (Loisel) Duby) Wood Surface: Effect of Thermo-Treatment and Alkyl Ketene Dimer (AKD)." Forests 10, no. 9 (September 5, 2019): 770. http://dx.doi.org/10.3390/f10090770.

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The main purpose of this study was to investigate the hydrophobic effect and chemical changes induced by thermo-treatment and alkyl ketene dimer (AKD) on the surface properties of Alder (Alnus cordata (Loisel) Duby) wood before and after an artificial weathering test. Thermal treatment was conducted at a temperature of 200 °C for 4 h in a thermo-vacuum cylinder. Then, the paper sizing agent, AKD at different concentrations of a solution of 0.1%, 0.5% and 10% was used as a potential hydrophobizing reagent for untreated and thermally treated alder wood surfaces. The contact angle measurement, ATR-FTIR analysis and colour variation were carried out for the samples. The preliminary results revealed that the contact angle values of the wood materials increased with thermal modification. However, the influence of the thermal treatment on hydrophobicity was small when compared to the substantial effect of the AKD application in this respect, and also after the artificial weathering test. The FTIR analysis supported the hypothesis that AKD could make bonds chemically stable even when using a small concentration of AKD. The findings acquired in this work provide important information for future research and the utilization of the AKD on lesser-used wood species.

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Oukach, Soufiane, Hassan Hamdi, Mohammed El Ganaoui, and Bernard Pateyron. "Protective Plasma Sprayed Coating forThermo-Sensitive Substrates." MATEC Web of Conferences 307 (2020): 01039. http://dx.doi.org/10.1051/matecconf/202030701039.

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Plasma spray is one of the surface treatment techniques that consist on the deposition of a thin coating onto a targeted substrate. Coating is built up by successive accumulation of layered splats resulting from impact and solidification of molten particles into thin ‘‘splats’’ onto the substrate. The process of droplet impact, spreading and solidification is then a crucial process in coating formation. This technique may be also used for thermo-sensitive materials such as wood by applying a metallic coating for protective or decorative purposes. However, when applying a ceramic coating which provides a high protection against hot temperatures like fire, wood may be damaged because of the high temperature at which the ceramic molten particles arrive at the substrate. In this paper, a numerical simulation based on the Finite Elements Method is carried out in order to simulate the process of the first splat formation onto a wood substrate under traditional plasma spraying conditions. The computations are carried out on a fixed eulerian structured mesh using the level set method to track the interface between the molten particle and surrounding gas. The effects of operating conditions as well as the droplet characteristics that allow applying ceramic coating onto a wood substrate without any damage to this thermo-sensitive material are investigated.

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Grinins, Juris, Bruno Andersons, Ilze Irbe, Ingeborga Andersone, Anete Meija-Feldmane, Anna Janberga, Gunars Pavlovics, and Errj Sansonetti. "Thermo-hydro treated (THT) birch veneers for producing plywood with improved properties." Holzforschung 70, no. 8 (August 1, 2016): 739–46. http://dx.doi.org/10.1515/hf-2015-0155.

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Abstract The effect of thermo-hydro treatment (THT) on the properties of birch (Betula spp.) wood veneers has been studied. THT was carried out in a multi-functional pilot scale wood modification device of wood treatment technology (WTT, Latvia) under elevated water vapor pressure conditions at four combinations of temperature and treatment time (°C/min): 150/10; 150/50; 160/10 and 160/50. After THT, the following veneer properties were examined: mass loss (ML), chemical composition, bending strength (BS), tensile strength (TS), equilibrium moisture content (EMC), resistance to decay by mould and blue stain fungi, and surface contact angle (CA). The chemical components were changed by THT. Increased THT temperature and time resulted in hydrophobization of veneers as indicated by decreasing EMC and increasing CA data. All THT were effective against wood discoloring fungi, although insufficient decay resistance was observed. The mechanical strength properties of THT veneers were also deteriorated.

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40

R. Shaikhutdinova, A., R. R. Safin, F. V. Nazipova, and S. R. Mukhametzyanov. "Use of Thermo-Modified Wood Massif in Making Parametric Exterior Furniture." International Journal of Engineering & Technology 7, no. 4.36 (December 9, 2018): 1112. http://dx.doi.org/10.14419/ijet.v7i4.36.25045.

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This paper proposes the use of an array of heat-treated wood of various species to make parametric furniture for the purpose of operation in the exterior, and on objects in conditions of high humidity. The dependence of change in the color range of thermowoods depending on the temperature and duration of treatment is presented. Experiments were carried out to study the biological stability of thermally modified wood treated by various technologies including: vacuum-convective thermal modification in superheated steam, convective thermal modification in high-pressure saturated steam, as well as in hydrophobic liquids, in flue gas and vacuum-conductive thermal-modifying. The degree of resistance of wood was determined, which allows to conclude that the mass losses of heat-treated specimens caused by the destructive action of fungi are significantly lower compared to untreated ones. The researchwas conducted to determine the numerical characteristics of microroughness of the polished surface of wood, thermally modified at different temperatures.

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Shaikhutdinova, Aigul Ravilevna, Ruslan R. Safin, and A. E. Voronin. "Technologies for Manufacturing of Moisture-Resistant Products from Modified Wood." Materials Science Forum 945 (February 2019): 281–86. http://dx.doi.org/10.4028/www.scientific.net/msf.945.281.

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Wood, as a finishing and building material, has always been given special attention. Wood has many positive properties, but it's no secret that faced with its shortcomings such as fragility, instability of form and susceptibility to decay, people often prefer synthetic materials, putting aside the ecology and useful properties of wood and choosing the long life of non-natural materials. In this regard experts around the world are constantly searching for new solutions aimed at improving the physical, mechanical and operational properties of wood, which would allow a person to limit the use of artificially created analogs of natural materials and enjoy the atmosphere of tranquility and appeasement in a house that can create a tree. Analyzing the knowledge and skills of previous generations the author of the article took as a basis various technologies of deep processing with the aim of improving the quality, extending the service life and expanding the scope of its use, thanks to which a new modern moisture resistant "hardened" tree is created for furniture, interior, finishing elements for garden houses and plots. Experiments have been carried out to investigate the biological resistance of wood thermo modified in five different technologies: vacuum-convective thermal modification in a superheated steam, convective thermal modification in a saturated high-pressure steam environment, thermal modification of wood in hydrophobic liquids, thermal modification of wood in a flue gas environment and vacuum-conductive thermal modification. The degree of moisture resistance of the samples is calculated, which makes it possible to conclude that the mass of thermo-modified wood is significantly lower, caused by the destructive effect of fungi, as compared to untreated samples. The most optimal technology for structures involving close contact with water or soil is determined.

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Dubey, Manoj Kumar, Shusheng Pang, Shakti Chauhan, and John Walker. "Dimensional stability, fungal resistance and mechanical properties of radiata pine after combined thermo-mechanical compression and oil heat-treatment." Holzforschung 70, no. 8 (August 1, 2016): 793–800. http://dx.doi.org/10.1515/hf-2015-0174.

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Abstract The dimensional stability and mechanical properties of radiata pine (Pinus radiata) has been investigated after thermo-mechanically compression (TMC) followed by oil heat-treatment (OHT). Wood specimens were first compressed in the radial direction then heat-treated in a linseed oil bath at 160–210°C. Spring-back percentage, water repellence efficiencies, and compression set recovery percentage were determined as indicators of dimensional stability. The resistance of treated wood against a brown rot fungi was assessed based on an accelerated laboratory fungal decay test. Strength, stiffness and hardness were determined as a function of different treatment parameters. After TMC, high compression set (39%) was achieved without any surface checks and cracks. Specimens undergoing TMC followed by OHT showed relatively less swelling and low compression set recovery under high moisture conditions. The fungal resistance of wood after TMC+OHT slightly increased compared to untreated wood and TMC wood. The mechanical properties of TMC+OHT wood were inferior to those of TMC wood.

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VILLA, KEVEN, CESAR ECHAVARRIA, and DANIELA BLESSENT. "Wood walls insulated with coconut fiber." DYNA 86, no. 210 (July 1, 2019): 333–37. http://dx.doi.org/10.15446/dyna.v86n210.73685.

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Solid wood gives the shape to walls, while panels are the coating and they are nailed or screwed to the wood sections. In the cavities between the wood elements and the panels, a thermal and acoustic insulator must be added. Unfortunately, almost all of the currently used insulators (mineral wool, expanded polystyrene, polyurethane) are not biodegradable and require the use of vapor barriers (polyethylene sheets, aluminum foils, etc.) that deteriorate rapidly and that are relatively environmentally unfriendly. In this article, the use of coconut fiber instead of conventional insulators is suggested. The acoustic absorption and thermal conductivity coefficients of composite sections taken from wood walls with coconut fiber are estimated. In this way, good thermo-acoustic conditions inside the wood building are achieved using an ecological insulating material.

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44

Lesar, Boštjan, Miha Humar, Frederick A. Kamke, and Andreja Kutnar. "Influence of the thermo-hydro-mechanical treatments of wood on the performance against wood-degrading fungi." Wood Science and Technology 47, no. 5 (May 18, 2013): 977–92. http://dx.doi.org/10.1007/s00226-013-0553-8.

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45

Копылов, Николай Петрович, Александр Евгеньевич Кузнецов, Елена Юрьевна Сушкина, and Владимир Васильевич Яшин. "Study of the kinetics of thermal and thermal-oxidative destruction of treated with flame retardants and untreated wood (Part 2)." Pozharnaia bezopasnost`, no. 4(101) (December 7, 2020): 55–62. http://dx.doi.org/10.37657/vniipo.pb.2020.101.4.005.

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Проведена серия экспериментов по оценке огнезащитного действия антипиренов на древесину. Исследования выполнены для бишофита на специально созданной экспериментальной установке. Кинетика выделения дымового аэрозоля изучалась с помощью фотометра фотоэлектрического ФАН, а для проведения количественных расчетов абсолютных значений дымовых аэрозолей применялся отбор проб на фильтры АФА-ВП. Количественные оценки скоростей различных стадий термической и термоокислительной деструкции получены методом формально-кинетического расчета. The choice of flame retardants as additives to water when extinguishing forest fires should be based on a preliminary (laboratory) study of their fire-retardant properties for wood, determining the mechanisms of fire-retardant action. Evaluation of the effectiveness of a particular flame retardant can be carried out by studying the kinetics of thermal and thermo-oxidative degradation of treated and untreated wood. The purpose of this work is to supplement the method for evaluating the fire-retardant effect of flame retardants solutions with methods for studying the rates of smoke aerosol release and its amount during thermal and thermo-oxidative destruction of wood. Quantitative rate estimates of various stages of thermal and thermo-oxidative degradation are obtained by the method of formal kinetic calculation based on experimental data on the rates of smoke aerosol release. The calculation showed that treatment with flame retardants (in this case MgCl) reduces the activation energy of dehydration and depolymerization processes from 83.68 to 75.31 kJ/mol (for 8% solutions) and to 58.58 kJ/mol (for 35% solutions). This indicates that the halides of magnesium are as catalysts of dehydration in the present case. Kinetic analysis allows to conclude that the treatment of wood with flame retardant (MgCl) reduces the amount of smoke aerosol released during thermal degradation, and at the same time it accelerates the processes of heterogeneous oxygen enrichment of substances on the surface of the carbonized residue.

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Şenol, Süleyman, and Mehmet Budakçı. "Effect of Thermo-Vibro-Mechanic® Densification Process on the Gloss and Hardness Values of Some Wood Materials." BioResources 17, no. 4 (October 21, 2019): 9611–27. http://dx.doi.org/10.15376/biores.14.4.9611-9627.

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This study aimed to determine the gloss and hardness values of low-density wood materials densified using the Thermo-Vibro-Mechanic® (TVM) method after pretreatment with wood stain and wood preservative. This was carried out with a TVM density press that was designed and produced with the support of project 115O138 of the Scientific and Technological Research Council of Turkey (TUBITAK). The samples obtained from Uludağ fir (Abies bornmüelleriana Mattf.) and black poplar (Populus nigra L.) were pretreated with wood stain and wood preservative prior to the TVM densification process. The TVM densification operation was conducted at three different temperatures, three different vibration pressures, and three different vibration times. After the TVM densification process, changes in the gloss (ISO 2813 2014) and Brinell hardness values (TS 2479 1976) of the samples were determined. According to the results, the TVM densification method increased the gloss value of the Uludağ fir and black poplar wood pretreated with the wood preservative by 175% and 1390%, respectively, and increased the Brinell hardness value by 63% and 150%, respectively.

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47

Miljkovic, Jovan, Ivana Grmusa, Milanka Djiporovic, and Zorica Kacarevic-Popovic. "The influence of fire retardants on the properties of beech and poplar veneers and plywood." Bulletin of the Faculty of Forestry, no. 92 (2005): 111–24. http://dx.doi.org/10.2298/gsf0592111m.

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Rising demands for fire resistance properties of wood construction and elements matching new standards have been an important part of building codes during the last decade. On the other side, lack of more detailed research on interaction between wood species and selected fire retardant chemicals even with basically one is evident. This is particularly truth with domestic wood species. In this research, beech and poplar veneers were immersed in 25% solutions of monoammonium phosphate (MP) and sodium acetate (SA) and impregnated for different periods of time. To determine the preliminary level of fire retardancy achieved in veneers before manufacturing of finished plywood, thermo gravimetric (TG) and derivative thermo gravimetric (DTG) methods were used. TG and DTG analyses of treated and untreated wood, as well as of fire retardants alone, were performed. The next properties of impregnated and no impregnated veneers and plywood were determined: absorption of imp regnant solution (A), weight percent gain (WPG) of imp regnant, equilibrium moisture content (EMC), pH values, and in the case of plywood, strength and fire resistance. Fire resistance of plywood was tested in accordance with standard test for resistance to the effects of fire and the most efficient fire retardant, monoammonium phosphate, had the same result as TG/DTG analyses, which pointed out the validity of TG methods in predicting fire resistance of future products.

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48

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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Novel, David, Simone Ghio, Andrea Gaiardo, Antonino Picciotto, Vincenzo Guidi, Giorgio Speranza, Maurizio Boscardin, Pierluigi Bellutti, and Nicola M. Pugno. "Strengthening of Wood-like Materials via Densification and Nanoparticle Intercalation." Nanomaterials 10, no. 3 (March 6, 2020): 478. http://dx.doi.org/10.3390/nano10030478.

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Recently, several chemical and physical treatments were developed to improve different properties of wood. Such treatments are applicable to many types of cellulose-based materials. Densification leads the group in terms of mechanical results and comprises a chemical treatment followed by a thermo-compression stage. First, chemicals selectively etch the matrix of lignin and hemicellulose. Then, thermo-compression increases the packing density of cellulose microfibrils boosting mechanical performance. In this paper, in comparison with the state-of-the-art for wood treatments we introduce an additional nano-reinforcemeent on densified giant reed to further improve the mechanical performance. The modified nanocomposite materials are stiffer, stronger, tougher and show higher fire resistance. After the addition of nanoparticles, no relevant structural modification is induced as they are located in the gaps between cellulose microfibrils. Their peculiar positioning could increase the interfacial adhesion energy and improve the stress transfer between cellulose microfibrils. The presented process stands as a viable solution to introduce nanoparticles as new functionalities into cellulose-based natural materials.

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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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Journal articles on the topic 'Thermo-wood'

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