PSI - Issue 59

Sviatoslav Homon et al. / Procedia Structural Integrity 59 (2024) 595–600 Sviatoslav Homon et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Wood is one of the most promising natural materials (Da Silva and Kyriakides (2007), Homon et al. (2023), Janiak et al. (2023), Gomon et al. (2023); Zhao et al. (2020)) used in various industries (Rudavska et al. (2018), Sobczak-Piastka et al. (2023), Bosak et al. (2021), Gomon et al. (2022); Donadon et al. (2020); Pavluk et al. (2023)). In certain cases, it has to exhibit enhanced characteristics (Gomon et al. (2022), Yasniy et al. (2022), Sobczak Piastka et al. (2020), Huang et al. (2006); Soriano et al. (2016)). One way to enhance wood properties is its modification. The wood modification process involves the improvement of a range of physical and mechanical properties (Bojok and Vintoniv (1992), Yasniy et al. (2022)). Despite extensive experimental research, enhancing and improving wood qualities (physical, mechanical, biological, hygroscopic, etc.) remains open and relevant. European and American scholars have conducted significant research on modifying wood properties. Hill C. (2007) suggests various methods and techniques for wood modification, including chemical, thermal, acetylation, impregnation, and others. Using environmentally friendly practices and incorporating ecologically clean additives in wood modification are emphasized. Several scholars actively advocate for enhancing wood properties with complex modifiers based on mineral and natural oils (Sandberg et al. (2017), Wo´zniak (2020), Yaris et al. (2020)) . This research direction also considers using oils (linseed, tall) to enhance wood stability. One effective method of wood modification is physical, involving the impregnation of the natural material (Hill C. (2011)), typically carried out in production conditions through autoclave treatment (applying temperature and pressure parameters to the material). Additionally, the condensation modification method, which involves the influence of atmospheric pressure on the wood, is known. It has been established that for wood impregnation, solutions based on oils and resins with the addition of components that accelerate their polycondensation and contribute to property improvement are used (resistance to temperature changes, atmospheric or biological influences, etc.). 2. Methodology of experimental research The experimental research used wood species such as pine, birch, and spruce. The size of the prism twins, manufactured in factory conditions, was 30x30x120 mm. The samples were obtained by cutting from beams pre dried to a standard moisture content of 12%, determined by the MD-814 moisture meter. A batch of 3 samples from the specified wood species, approximately 60 years old, was selected for the experiment. Wood modification was performed using a physical impregnation method with an autoclave installation. The impregnation of wood samples was carried out in three stages: I stage – preparation of the installation and samples (pressure, temperature, duration, etc.); II stage – introduction of the impregnating liquid (tar oil and boric acid (2%)); III stage – injection of linseed oil into the reservoir and holding the prisms under a vacuum. The scope of the experimental research is presented in Table 1. Nomenclature t temperature of the solution in the autoclave chamber ultimate compressive strength of wood along the fibers f c,0,d

Table 1. Scope of experimental research on solid modified wood.

Temperature, 0 C Number of samples, pcs

Wood species Method of modification Impregnation time, minutes

Thousand, MPa

Pine

Physical modification Physical modification Physical modification

30 30 30

1-1.5-2 1-1.5-2 1-1.5-2

60-75-90 60-75-90 60-75-90

9 9 9

Birch Spruce