Results of experimental studies on the strength of adhesive-bonded joints of thermally modified ash wood

It is necessary to ensure the protection of the adhesive-bonded wood structures from the effects of temperature and humidity loads to improve their performance characteristics and increase the service life – this determines the relevance of this study. The purpose of the study is to examine, using a long-term method, the strength of thermoplastic adhesive-bonded joints of thermally modified ash wood and unmodified pine wood. The data were subjected to statistical processing and analysis. The experimental samples for the studies were prepared according to the proposed methodology in production conditions according to the existing technological process. The studies continued for two years, with periodic inspection of the samples and recording of the changes that occurred during the experiments. Regularly, every three months of the study, part of the samples was removed from the stand and tested to determine the change in strength. Methods were selected and described for conducting long-term experimental studies to determine the strength of adhesive joints of thermally modified ash wood and unmodified pine wood glued with polyvinyl acetate-based adhesives with durability class D4. Based on the study results, it was identified that the average strength of control samples of the thermally modified ash wood and unmodified pine wood was 7.12 MPa, and after two years of long-term testing, it decreased to 5.13 MPa (27.9%). In addition, it was identified that the operation of such adhesive-bonded joints in natural conditions depends on the cyclic temperature-and-humidity load. Namely, in the summer-autumn period, the strength decreases, while in the winter-spring period, it remains unchanged, and in some cases, increases. The obtained results are of great practical importance, since such adhesive-bonded structures, can be used for the manufacture of joinery and building products, which will improve their performance characteristics and increase their service life