Author: Panayot Panayotov
Articles
- RESEARCH OF WATER VAPOUR ADSORPTION OF THERMALLY MODIFIED BEECH, SPRUCE AND POPLAR WOOD
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Summary
For use in this search, was realized thermally treatment by temperature 210ºC on spruce, beech and poplar wood in sunflower oil and glycerol environment. Thermally treated wood have some differences from natural, like colour, odor, density and other physical and mechanical properties. From this wood was produced samples with measure 30х30х10mm (last one in longitudinal direction). In parallel with this was produced control samples from same wood dried to constant weight by temperature 102±3ºC. It was determinate water vapour adsorption of samples according to BDS 16987-89.
Keywords: wood, spruce, beech, poplar, water vapour adsorption, thermally modified wood
- INFLUENCE OF WATER-THERMAL CYCLIC TREATED ON THE ADHESION OF PROTECTIVE COATS, FORMED ON WOOD
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Summary
Wood outdoor exposed in normal atmospheric condition affect the colour and texture due to the impact of UV spectrum of light. Although UV rays penetrate into the wood to a depth of not more than 75–100 µm, they are main cause for initiation of weathering it, due to the conduct of complex and physical- chemical processes. As a result of the combined effects of climatic factors, significant structural changes occur in the surface layer (surface erosion). These changes are denoted by the term weathering. This is impact on the aesthetic appearance of the product and the quality of protective coatings. The water plays an important role for wood destruction. The weathering could be minimizing with surface treatment. These treatments can be performed both with soaking up funds forming protective and decorative coatings. The function of these coatings is to receive and minimize external impact and thus extended to life of articles, therefore increase their durability. It is perform an analysis of adhesion of protective and decorative coatings, formed on building wooden products, water-thermal cyclic treated. It is established that the adhesion decrease after water-thermal treating. It is establish that the water penetrates through to the coats distort its adhesion to wood surfaces. It is made recommendation about the conduct of appropriate activities for coating refresh.
Keywords: wood elements, protective coats, building products; water-thermal treatment
- METHODS OF FORMING COATS WITH ANTIQUE EFFECT
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Summary
Methods of finishing for creating antique effects were analyzed. It was established that to create these finishes - chemical stains, patina powder, sealer and top-coats are used. It is easy and quick to achieve these effects, when they are formed on tannin-containing wood. It is established that antique effects can be coated on wood which doesn’t contain tannin (Spruce, Scots Pine), if the effects are made by suitable stains, paints and top-coats. It was made technologies for making „multicolored chestnut“, „antique paint“ and „crackle“ effects on chestnut and ash wood. These special effects are in use in modern fluency in furniture with antique effects. The most important qualities were explored.
Keywords: wood, chemical stains, old finishes, furniture with antique effect
- EARTHQUAKE RESISTANCE OF TIMBER STRUCRUTRES
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Summary
The prime objective of this paper is to describe the basics of the seismic design of the timber constructions. The experience from North America and Japan shows that when designed properly wooden structures can resist extreme conditions like earthquakes. The ability of structures to develop plastic deformations without drastic reduction of strength and resistance is called ductility. The purpose of this paper is to present the ductile behavior of the timber structures in tree directions – material; element/joints; structure as a whole. Timber has orthotropic properties and although it behaves in ductile manner when loaded under compression, especially perpendicular to the grain, it is brittle under tension perpendicular to the grain. The connections in timber structures introduce a foundational aspect in terms of the seismic behavior of the construction, since they act as ductile valves and enable dissipation of energy. Due to its global ductility, the structure posses the ability to withstand deformations without developing high stress concentrations. Seismic resistance of timber structures is based on their advantages – a low-self load; ductile joints; in general very regular building layouts. The paper was done as a specialized literature survey and is based on the conceptions of the capacity seismic design and the system of structural Eurocode standards (EN 1995-1-2:2004 and EN 1998-1:2004).
Keywords: seismic design, timber constructions, earthquakes
- COMPARATIVE CARRY OUT OF ADHESION OF THE ADHESIVE FILMS FORMED BY CARBAMIDEFORMALDEHYDE AND ACETATE POLYMER ADHESIVES
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Summary
This report experimentally examined adhesion of adhesive films formed by carbamideformaldehyde and polyvinilacetate adhesives to wood. It is influence of some factors (roughness gluing surfaces, specific pressure, temperature) on the values of adhesion. For this purpose used test fixtures from beech wood, glue carbamidformaldehyde PREFERE 4114 and polyvinilacetate polymer adhesive Jowacoll 124.00. Strength of adherence was defermined under the regulation of EN 302 and BS EN 205.
Keywords: gluing; adhesion, wood, reactive glues; PVAc adhesives
- ADHESION OF PROTECTIVE DECORATIVE COAT FORMED BY SYSTEM „SADOLIN“ TO SPRUCE TIMBER IMPREGNATED WITH ANTISEPTIC COMPOUNDS
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Summary
Research has been carried out for the defining of the adhesion of the protective decorative coat, formed by the varnish system Sadolin, towards spruce timber, impregnated with antiseptic compounds Tanalit E 3492 and Resistol. The impregnation has been carried out by dipping in a tank with duration of 5, 15, 60 and 1440 min and in a autoclave by the method of vacuum-pressure. In this way in the surface layer a different dry quantity of antiseptic has been integrated. The applied system Sadolin consist of primmer (Sadolin base) and lacquer (Sadolin extra). The primer has been put in one layer and the lacquer in four layers. Adhesion has been tested by the method of put-out of glued metal cylinder, defined by Standard BDS EN 4624 (BDS 13088). It has been found that the quantity of the integrated antiseptic influences the adhesion of the coat to the timber base.
Keywords: adhesion; coats; spruce timber; antiseptic compounds; impregnation