Effect of the Reinforced Plastic Clamp Fitting on the Bending Strength of the Spruce T-Type Loose Tenon Joints

This article presents the bending strength and flexural properties of the glued T-type spruce loose tenon construction joints with and without reinforced plastic clamp fitting. Construction joints are designed according to Eurocode 5. The samples are made from European spruce (Picea abies Karst.) C24 class construction material with relative wood moisture 18% and relative wood density 410 kg/m3. Samples are assembled with water/high temperature resistant polyurethane adhesive and polyvinyl acetate dispersion adhesive. The total number of samples is 48. The sample width is 95mm and thickness is 45mm. Samples were subjected to moisture, weight controls and 48h stored in the climate chamber before practical bending load test. T-type loose tenon joint construction samples with reinforced plastic clamp fittings glued with polyurethane adhesive under bending load are 2.6% stronger and 13.8% less flexural then without reinforced plastic clamp fittings. T-type loose tenon joint construction samples with reinforced plastic clamp fittings glued with polyvinyl acetate dispersion adhesive under bending load are 9.7% weaker and 20% less flexural then without reinforced plastic clamp fittings. The accuracy of the developed bending strength, deformability and elasticity modulus of the examined construction joints was verified positively by experimental studies.

Technology of Production of Binder Modifying Nanoadditives

The article deals with the issue concerning production of a dry nanoadditive. In order to achieve this goal, an aqueous solution of polyvinyl acetate dispersion (PVAD) and nanotubes, or lime slaking nanoparticles is used. As a result of the hydration process heat is released, the polyvinyl acetate emulsion forms particles with nanotubes in their composition. During the study performed an optimal ratio of all components was established: quicklime + PVAD-CNT – 71-73% and 0.01-0.018 CNT; “Megalith” – 21-25%; ammonium salt – 4-6%, as well as the optimal amount of the complex additive, which is in the range of 1-1.5% by weight of calcium sulfate hemihydrate. Later on the resulting nanoadditive can be used to modify binders or other materials

DEVELOPMENT OF ECO-FRIENDLY WATER-DISPERSION PAINT BASED ON POLYVINIL ACETATE DISPERSION

Interior paint is important for interior decorating; this is followed by a long time working with the col-oring material and a constant stay in rooms with the paint. Unfortunately, not all paints provide com-fortable and safe use. This article presents the development of eco-friendly water-dispersion paint based on polyvinyl acetate dispersion. This paint provides protection from carcinogenic, mutagenic and toxic effects. The main environmental requirements set by the standards are considered; the con-tent of substances in the paint that harms people is monitored. The influence of some paint compo-nents on person’s functionality and the possibility of their replacing without quality reduction is dis-closed in the paper. The main physical and mechanical properties such as conditional viscosity, densi-ty, mass fraction of nonvolatile substances, coating adhesion, milling degree, resistance to static ac-tion of water and weather resistance are determined. Attention is paid to the applied research meth-ods. As a result of testing, a water-dispersion paint with high technical characteristics is obtained. It can be used in all types of buildings and structures and be recommended for children's, medical and preventive institutions.

Decrease in the deflection of the furniture boards revetted paper and layered plastic

One of the main objectives of the enterprises for production of furniture is decrease in a material capacity of production and as a result decrease in its prime cost. Producers of kitchen table-tops for this purpose pass to production of table-tops of the combined design, replacing thick wood-shaving plates 25, 38 mm thick, with thinner 16 mm.For maintenance of more massive appearance of such table-tops to thin wood chipboard in the longitudinal direction at the edges of a board paste longitudinal strips from chipboard. The economy of material can lead to a deflection, the received table-tops. In this work the deflection of table-tops of the combined design was investigated. For studying of the reasons of emergence of a deflection and ways of its decrease the samples received in laboratory and working conditions were investigated. For pasting of boards from chipboard the paper and layered plastic used glue on the basis of polyvinyl acetate dispersion and the combined glue with various ratio of urea-formaldehyde resinand polyvinyl acetate dispersion. At the first stage defined a deflection of not revertedwood-shaving plates. Then controlled change of a deflection after gluing of plastic, paper from the back (and, paper and plastic made a veneering consistently and at the same time), after gluing of levels from chipboard. The deflection was defined in various directions of a furniture board in dynamics. Determined durability of gluing of plastic by above-mentioned glues. As a result of work it is established that the veneering of the front and reverse parties of plates in a hot press needs to be made at the same time. By production of the combined design of table-tops it is more expedient to use pure polyvinyl acetate dispersion. Durability on a plastic separation from wood-shaving plates is higher when using of the mixed glue on the basis of polyvinyl acetate dispersion and urea-formaldehyde resin.