Wood is a material with unique properties that contribute to its wide use as a raw material for various types of industries. Different quality requirements are imposed on the raw materialdepending on the material or wood product. However, physical and mechanical properties of wood are not homogenousalong the radius and height of the trunk and depend on the species, location in the trunk and growing conditions. The aim of this research is to study the variability of porosity and density of Scots pine (Pinus sylvestris L.) wood in a tree trunk growing in dry forests of the forest-steppe zone of the Russian Federation. The studies were carried out on wood cuts, sawn at different trunk heights. The change in the density of pine wood along the height of the trunk by 1.43% for each meter has been established. The wood porosity increases from the butt to the top by an average of 5.5%. New information about the variability of wood properties makes it possible to rationally and reasonably approach the choice of raw materials for obtaining materials with specified performance characteristics.
The article presents the results of experimental studies of the effect of forest fires on the structure of the annual layer and its parts of pine wood. The harmful effect of forest fires is expressed, first of all, in the direct destruction and damage of wood by fire. Wood raw materials harvested from various growing conditions differ in a number of qualitative indicators. In the practical use of wood damaged by fire, the characteristics of the macrostructure are used for a preliminary assessment of its quality, calculated for the most part according to the parameters of the annual layer. The revealed changes in the pre-fire and post-fire growth of wood will allow us to judge the quality and vital activity of pine stands growing in forest-steppe conditions.
Abstract Glues are widely used to connect various materials, especially since in some cases other options for combining materials are not suitable. The paper deals with the bonding of solid hardwood with modern adhesive materials. Currently, a large group of adhesives of various brands from Russian and foreign manufacturers is presented on the market. In the woodworking industry, adhesives are used in the carpentry and furniture, manufacturing, in wooden house-building, in the production of finishing materials, etc., which are operated outside and inside the premises in constant and variable humidity conditions. Therefore, the correct choice of adhesives plays an important role both for the manufacturer and subsequently for the consumer of the resulting product. In this work, we have studied the dependence of the tensile strength when chipping along the adhesive layer on the type of glue, wood species, and operating conditions. We have selected the following adhesives based on polychloroprene, polyvinyl acetate and rubber. The greatest strength of the adhesive bonding when gluing solid hardwood is given by polyvinyl acetate adhesives. When using the product in conditions of changing temperature and humidity, the bonding strength decreases, in some cases significantly. In fairness, it should be noted that not only the type of glue, but also the type of wood affects the bonding strength
According to European standards, the most stringent standards for the content of formaldehyde belong to the emission class E 0.5. The hardening of resins with different formaldehyde content is different and it has not yet been sufficiently studied. The production of the woodworking industry face difficulty in the use of low toxic urea-formaldehyde resins. On the one hand, life and standards require environmentally friendly products, on the other hand, the use of low-toxic resins leads to a large percentage of defects in the production process, reduced productivity and deterioration of the strength properties of the finished product. The polycondensation reaction of low-toxic resins using a classical hardener-ammonium chloride is slower in comparison with resins with a high content of formaldehyde, that is, performance is reduced. The paper examines the influence of various hardeners on the physical and chemical properties of the glue (gelatinization time, viability, pH of liquid and cured adhesives). All the studied preparations can be used as a hardener of low-toxic urea-formaldehyde resin, but its content should be adjusted taking into account the physical and chemical parameters of the initial state of the resins and production conditions.
The article provides brief information from the life and scientific work of the founders of the Faculty of Forestry Engineering and the Faculty of Woodprocessing Technology (currently the Faculty of Forestry Industry). 2020 marks the 90th anniversary of the establishment of Voronezh University of Forestry and Technologies. Celebrating the 90th anniversary of the existence of the university, it would be fair to recall the names of the scientists who stood at the origins of the forest engineering faculty and the faculty of woodprocessing technology. Many generations of scientists have been involved in the organization and development of faculties, who have made a significant contribution to the development of the forest complex of Russia. They are widely known not only in our country, but also abroad. These are: V.K. Kuryanov, V.I. Kharchevnikov, F.V. Posharnikov, V.P. Zhukov, A.A. Filonov, P.N. Khukhryansky, T.K. Kuryanova, N.I. Popova, L.I. Belchinskaya. This publication provides information from the life of the scientists who stood at the origins of the creation and development of the scientific authority of Voronezh Forestry School. A number of information about the life and work of these outstanding researchers was borrowed by the authors from the sources cited, and some data were supplemented by personal memories of people with whom the authors communicated
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