Abstract
The object of research is a promising structural material – modified wood. Extending the use of wood while maintaining structural characteristics is a promising area of research. Modification of wood in accordance with structural requirements, taking into account sanitary and other requirements, is an important task. The most common modification technologies are impregnation. Pressure autoclaving wood requires sophisticated equipment to create unprofitable pressure. Impregnation by the condensation method or the method of «cold and hot baths» significantly reduces the cost of obtaining modified wood. The study of the stability of the geometric dimensions of modified wood under the moisture influence makes it possible to evaluate the effectiveness of the modification (impregnation) process and, as a result, evaluate the service life. Samples from pine timber (DSTU ISO 738:2018) with a size of 300–70–15 mm are used. For research, three groups of samples are selected with radial (R), tangential (T) and mixed (M) direction of wood fibers. For impregnation modification, linseed oil and drying oil were used at a concentration of 25 g/l. In accordance with the modification technology, the samples are soaked in an aqueous solution with a desiccant, then immersed in linseed oil heated to 130±10 °С, and then immersed in linseed oil at a temperature of 20 °С. The obtained samples are dried under atmospheric conditions and soaked in water for 24 hours to study the stability of geometric dimensions. As a result of studies, it is found that the optimal temperature for heating the samples is the range 120–140 °C. It is also found that the most resistant to changes in geometric dimensions are samples with a mixed direction of the fibers (M), in which size changes are 0.5 % compared to dry samples. Regardless of the direction of the fibers, the moisture absorption of the modified samples is 0.07 vol. %, which is of great practical interest.
Highlights
Modified wood is used in the construction industry for the construction of buildings and technical facilities for long-term operation, providing them with deco rative and aesthetic properties
The impregnation of coniferous wood with resins based on melamine formaldehyde was studied in [8], and a number of wood properties, such as surface hard ness and weather resistance, are improved
To increase the dimensional stability and biological protection of the Japanese cedar, low molecular weight phenolic resins of the usual, alkaline, and neutral types are used for impregna tion; after impregnation, the wood is subjected to thermal hardening [9]
Summary
Modified wood is used in the construction industry for the construction of buildings and technical facilities for long-term operation, providing them with deco rative and aesthetic properties. This implies its resistance to atmospheric effects (temperature, moisture, ultraviolet radiation). Modification of wood involves the use of chemical, physical or biological methods to change the properties of this building material [1, 2]. To increase the dimensional stability and biological protection of the Japanese cedar, low molecular weight phenolic resins of the usual, alkaline, and neutral types are used for impregna tion; after impregnation, the wood is subjected to thermal hardening [9]. As a result of processing this wood, the elastic modulus increased from 10 GPa to 22 GPa, and bending strength from 10 MPa to 250 MPa
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