Myakush B. The development of strength and shape stability of parquet boards glued with thermoplastic adhesives

In the dissertation work, an important scientific and applied problem was solved, which consists in determining the patterns of the strength and shape stability of a three-layer parquet board glued with thermoplastic polyvinyl acetate adhesives. Replacement of thermosetting urea-formaldehyde adhesives with thermoplastic polyvinyl acetate adhesives to glue structural elements will increase the strength and shape stability of a three-layer parquet board during operation and ensure the environmental requirements of our time. A new mathematical model has been built for predicting the shape stability of a three-layer parquet board glued with thermoplastic polyvinyl acetate adhesives. Simulation modeling of the dependence of the shape stability of a three-layer parquet structure on changes in the air humidity and ambient temperature has been carried out. The patterns of changes in the stress-strain state of each layer of a three-layer parquet board depending on the influence of the air humidity and ambient temperature have been studied. The calculation has been carried out for load-bearing wood elements for laying a three-layer parquet. Experimental investigations were carried out to study the dependence of the strength of the upper surface layer of a three-layer parquet board glued with thermoplastic polyvinyl acetate adhesive with a load degree D4 on the gluing mode parameters, namely: glue spread, pressure and pressing time. A regression relationship was obtained. The operating parameters of gluing a three-layer parquet board for the given materials have been calculated. The shape stability of a three-layer parquet board glued with thermoplastic polyvinyl acetate adhesive with a bending deflection was determined experimentally. A simulation modeling of the dependence of the shape stability of a three-layer parquet board on loads has been carried out.