Influence of weathering on surface roughness of thermally modified wood

Keržič, Eli; Lesar, Boštjan; Humar, Miha

doi:10.15376/biores.16.3.4675-4692

Cited by 7 publications

(4 citation statements)

References 34 publications

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“…The values of the parameters Ra and Rz, in the case of the uncoated samples, show a clear increase following thermal treatment compared to the untreated wood, indicating that the heat caused the increase in the average roughness and maximum profile height, as previously observed for other wood species and explained based on the degradation of wood components [25,[54][55][56]. The application of the coating, in all cases, causes a decrease in roughness that is more evident if the product is applied via spraying (see values of Ra and Rz in Figure 5).…”

Section: Roughness Datasupporting

confidence: 75%

Improving the Technical Characteristics of Untreated and Heat-Treated Ayous Wood against Accelerating Ageing by Testing Two Application Modalities of an Innovative Polyurethane Coating for Outdoor Uses

et al. 2023

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This paper presents the results of tests of a new mono-component polyurethane coating for wood with the aim of evaluating its effect on Ayous (Triplochiton scleroxylon K. Schum), which is a wood species used in Europe for various applications, especially outdoors, after being heat treated. The coating was tested on both untreated and thermally treated samples, as the latter procedure is commonly used in the wood industry to modify the material’s characteristics. Moreover, two kinds of coating application were tested: coatings applied via brushing and coatings applied via spraying; in this test, we also verified the most suitable and effective modality. Samples were investigated using the following techniques: colour measurement, roughness mapping, contact angle measurement, surface micro-hardness and the wearing test; these techniques were applied before and after a period of artificial ageing under simulated solar irradiation. Upon synthesizing the main results, we identified the following results: (i) the polyurethane coating reduced the colour variation as a result of artificial aging of the untreated Ayous wood; in contrast, heat-treated wood underwent large colour changes; (ii) the coating acted effectively as a hydrophobic agent on the surface of the wood in each case examined, though even a short aging time altered the initial wettability characteristics; and (iii) the application of the coating caused a decrease in the roughness of both untreated and heat-treated surfaces, though this trend was much more evident in the case of the spray modality of application; however, aging always induced an increase in roughness, which was mainly observed in uncoated wood samples.

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Section: Roughness Datasupporting

confidence: 75%

Improving the Technical Characteristics of Untreated and Heat-Treated Ayous Wood against Accelerating Ageing by Testing Two Application Modalities of an Innovative Polyurethane Coating for Outdoor Uses

et al. 2023

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“…Thermally modified beech wood suffered a maximum strength reduction of 63% at a temperature of 210 °C/2 h. This is further evidence that thermal modification has a more positive effect on softwood species. In researchers [39][40][41] reported that the static modulus of elasticity (MOE) and modulus of rupture (MOR) of Scots pine wood increased when modified at 150 °C in an open reactor system using saturated steam, but decreased when modified at 180 °C. They also found that the tensile strength parallel to the grain decreased significantly after heat treatment, while the compressive strength parallel to the fiber increased.…”

Section: Maximum Bending and Tensile Forcementioning

confidence: 99%

Selected Mechanical and Physical Properties of Thermally Modified Wood after Field Exposure Tests

Dong

Hasanagić

Fathi

et al. 2023

Forests

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This study aimed to evaluate the impact of thermal modification on the physical and mechanical properties of three different wood species from Bosnia and Herzegovina, namely beech wood (Fagus sylvatica L.), linden wood (Tilia cordata), and silver fir wood (Abies alba). The samples underwent thermal modification at five different temperatures (170 °C, 180 °C, 195 °C, 210 °C, and 220 °C) for varying durations (ranging from 78 to 276 min). After treatment, they were exposed to outdoor conditions for twelve months. The study examined the four-point bending strength, tensile force, color change, and surface quality of the modified and unmodified samples. The results showed that outdoor exposure negatively impacted the mechanical properties of the unmodified samples, especially in the linden wood which was 41% and the beech wood which was 42%. Additionally, outdoor exposure caused significant surface cracks in the thermally modified linden and beech wood. The study also found prominent color changes in the modified and unmodified samples during twelve months of exposure. The roughness of the samples was determined with a confocal laser scanning microscope, which showed that the roughness increased on both the axial and the longitudinal surfaces after weathering. The highest roughness for the fir wood was determined to be 15.6 µm. Overall, this study demonstrates the importance of wood modification and its impact on the use-value of wood products.

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“…The purpose of study [3] was to determine whether moisture fluctuations are associated with the formation of cracks or roughness. Samples of common spruce, thermally modified spruce, European thermally modified spruce, and European larch core were subjected to artificial accelerated weathering and natural weathering for 9, 18, and 27 months.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Identifying parameters for wood protection against water absorption

Tsapko

Likhnyovskyi²,

Horbachova

et al. 2022

EEJET

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An issue related to using wood and timber for building structures is to ensure the stability and durability during operation within wide limits. Therefore, the object of research was the inhibition of the process of water absorption of pine and hornbeam wood during a thermal change in its structure. It is proved that in the process of thermal modification of wood, its structure changes, and, accordingly, water absorption. Namely, the maximum increase in mass under the action of water on an untreated sample of wood was more than 40 %, after thermal modification – less than 35 %. The increase in the mass of wood samples thermally modified and treated with a hydrophobic agent was less than 25 %. On the basis of the obtained results of physicochemical studies, discrepancies were found in the IR spectra of wood, both during thermal modification and with additional treatment with a hydrophobic agent, indicating structural changes in the components. In particular, the decrease or absence of the intensities of the absorption bands of some functional groups and the appearance or intensification of others. On the original hornbeam and pine thermogram, thermally modified, and thermally modified with the addition of a hydrophobic coating, thermogravimetric curves are similar to each other and are characterized by a loss of sample mass. This is possible with increasing temperature due to the processes of dehydration, destruction of hemicellulose, lignin, and cellulose with the formation of a non-combustible residue. During heat treatment of cellulose in the region of temperatures of 150÷450 °C, two processes take place in parallel. This is dehydration, accompanied by the destruction of the pyranose cycle and carbonization to form a carbon residue. Also, the process of destruction of glycosidic bonds while maintaining hydroxyl groups, accompanied by regrouping of pyranose cycles.

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Influence of weathering on surface roughness of thermally modified wood

Cited by 7 publications

References 34 publications

Improving the Technical Characteristics of Untreated and Heat-Treated Ayous Wood against Accelerating Ageing by Testing Two Application Modalities of an Innovative Polyurethane Coating for Outdoor Uses

Improving the Technical Characteristics of Untreated and Heat-Treated Ayous Wood against Accelerating Ageing by Testing Two Application Modalities of an Innovative Polyurethane Coating for Outdoor Uses

Selected Mechanical and Physical Properties of Thermally Modified Wood after Field Exposure Tests

Identifying parameters for wood protection against water absorption

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