National University of Forestry and Wood Technology of Ukraine

L'viv, Ukraine

National University of Forestry and Wood Technology of Ukraine

L'viv, Ukraine

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Noshchenko G.V.,National University of Forestry and Wood Technology of Ukraine | Salivon N.F.,National University of Forestry and Wood Technology of Ukraine | Zarychta B.,University of Opole | Olijnyk V.V.,University of Opole
Journal of Structural Chemistry | Year: 2013

Alternating-current electrochemical synthesis is used to obtain for the first time halogenocuprates of an allyl derivative of phosphonium of the composition (CH2=CHCH2(C6H5) 3P)CuX2 (X = Br (I), Cl (II)). Compound I crystallizes in the space group P21, a = 9.6341(3) Å, b = 12.4167(4) Å, c = 9.9618(4) Å, β = 117.484(5), Z = 2. Compound II crystallizes in the space group P21/n, a = 9.9725(5) Å, b = 15.4586(8) Å, c = 13.7557(5) Å, β = 90.429(4), Z = 4. In the structures of I and II quasilinear CuX2 - anions are held by C-H.X hydrogen bonds inside a framework formed by the stacking of phenyl groups from CH 2=CHCH2(C6P5)3P + cations. Allyl groups are not involved in coordination with copper(I) atoms. © 2013 Pleiades Publishing, Ltd.


Bekhta P.,National University of Forestry and Wood Technology of Ukraine | Lyutyy P.,National University of Forestry and Wood Technology of Ukraine | Hiziroglu S.,Oklahoma State University | Ortynska G.,National University of Forestry and Wood Technology of Ukraine
Journal of Polymers and the Environment | Year: 2016

The objective of this study was to evaluate some of the properties of experimental composite panels manufactured from waste packaging materials without using any additional binders. Particles from three types of materials, namely Tetra-Pak, food packaging films (FPEF) as recycled stretch wraps, and candy polyethylene wrappers (CPEW) were used at different ratios in the panels at a target density of 900 kg/m3. Modulus of rupture (MOR), screw holding strength and dimensional stability in the form of thickness swelling and water absorption of the panels were determined according to European (EN) standards. Based on the findings in this work it was determined that the ratio of different raw materials significantly influenced overall properties of the samples. The highest MOR value of 15.5 MPa was determined for the samples having 40 % Tetra-Pak and 60 % CPEW particles. Modulus of rupture values of the panels decreased with decreasing content of CPEW in the samples. The increased content of Tetra-Pak particles in the samples also resulted in reduction of their strength characteristics and dimensional stability. Properties of the samples considered in this work satisfied minimum requirements of typical particleboard stated in EN standards. It appears that such waste material would have potential to be used as raw material for value-added composite production using no adhesive in the panels and, therefore, such panels would possibly create significant ecological impact as green product. © 2016 Springer Science+Business Media New York


Bekhta P.,National University of Forestry and Wood Technology of Ukraine | Sedliacik J.,Technical University In Zvolen | Tymyk D.,National University of Forestry and Wood Technology of Ukraine
Acta Facultatis Xylologiae | Year: 2015

In this study, the chemical treatment of veneer surfaces was applied for minimizing surface inactivation and enhancing the bondability of wood veneers. The effect of different type of activating agents (hydrogen peroxide, aluminium persulfate, acetic acid, and sodium carbonate), their concentration (1%, 2% and 3%) and their amount (10, 20 and 30 g/m2) on the physical and mechanical properties of veneer surface and veneer-based products (especially plywood) made using treated veneers, was examined through laboratory tests. The results if this study revealed that chemical treatment of veneer surfaces increased their bondability. It was found that the samples of plywood panels made using treated veneers had higher shear strength than those of the control samples made using non-treated veneers. © 2015, Technical University in Zvolen. All rights reserved.


Bekhta P.,National University of Forestry and Wood Technology of Ukraine | Ortynska G.,National University of Forestry and Wood Technology of Ukraine | Sedliacik J.,Technical University In Zvolen
Drvna Industrija | Year: 2015

This paper presents the results of laboratory investigations of bonding high moisture content (15%) birch veneers (Betula pubescens Ehrh.) with the use of modifi ed phenol-formaldehyde (PF) resin. Wheat starch, rye fl our, resorcinol and phenol-resorcinol-formaldehyde resin were chosen as modifying agents. Dynamic viscosity, hydrogen ions concentration, solid content, curing time, pot life of developed adhesive compositions and shear strength of plywood samples were evaluated. ANOVA analysis has shown that type, mixture and content of modifying agents affect signifi cantly the mechanical performance of plywood panels. The obtained results of shear strength values were above the standard requirements (1 N/mm2), and the properties of samples met the European standard EN 314-2 for gluing quality of class 3 and such plywood panels can be used in exterior conditions. © 2015, Journal Drvna Industrija. All rights reserved.


Bekhta P.,National University of Forestry and Wood Technology of Ukraine | Sedliacik J.,Technical University In Zvolen
International Wood Products Journal | Year: 2015

The aim of this work was to study the bondability of birch (Betula verrucosa Ehrh.) veneer subjected to different surface treatments (chemical treatment, short term thermo-mechanical densification, and combination of these two processes) using phenol-formaldehyde (PF) resin with the aim of improving bonding during the production of plywood. Four chemical agents (hydrogen peroxide, aluminium potassium sulphate, potassium carbonate, and potassium permanganate) were used for chemical treatment of the veneer surface. The veneer samples were thermo-mechanically densified between heated plates of a laboratory press. The results revealed that short term thermo-mechanical densification and combined chemical and thermo-mechanical pre-treatment of the veneer surface prior to the resin application reduced the glue spread (a 33% reduction) and improved the bondability of the veneer. The obtained shear strength values for all of the studied treatments exceeded the standard requirements (1.0 MPa), and the properties of the plywood samples satisfied the European standard EN 314-2. © 2015 IWSc.


Bekhta P.,National University of Forestry and Wood Technology of Ukraine | Lyutyy P.,National University of Forestry and Wood Technology of Ukraine | Ortynska G.,National University of Forestry and Wood Technology of Ukraine
Drvna Industrija | Year: 2016

The effects of different kinds of coating materials on the properties of flat pressed wood plastic composite (WPC) panels were studied in this work. Rotary-cut birch veneer, sliced oak veneer, phenolic impregnated paper, polyethylene (PE) film, and recycled polyethylene (rPE) layer were used as coating materials. One or two-side coating of WPC panels was carried out simultaneously with their flat pressing. No coupling agents were used for production of WPC. It was found that properties of flat pressed WPC panels improved by coating with all investigated coating materials. The highest values of modulus of rupture (MOR) were observed in WPC panels coated with rotary-cut birch veneer and MOR values were higher in along direction than in across direction of veneer fibers. The highest values of water resistance were observed in WPC coated with PE film or rPE layer. Coating of WPC with natural veneer leads to the decreasing of water resistance. Besides, water resistance of WPC coated with one side of natural veneer was higher in comparison with two side coated WPC panels with natural veneer. The two-side coating of WPC with phenolic impregnated paper, PE film or rPE layer leads to the decreasing of water absorption and thickness swelling. © 2016, Journal Drvna Industrija. All rights reserved.


Sokolovskyi Ja.,National University of Forestry and Wood Technology of Ukraine | Mokrytska O.,National University of Forestry and Wood Technology of Ukraine | Krishtapovich V.,National University of Forestry and Wood Technology of Ukraine
Perspective Technologies and Methods in MEMS Design, MEMSTECH 2015 - Proceedings of 11th International Conference | Year: 2015

Within mechanics of heterogeneous media there was developed a mathematical model of stressdeformable - state of wood as a three-phase system consisting of solid (wood material), liquid and airvapor mixture phases. Defining relation allow to describe elastic, viscoelastic, residual strain deformations and deformations caused by mechanism of mechanical and sorption creep. The object-oriented software was created to implement the mathematical model of viscoelastic deformation of capillary-porous materials using the finite element method. © 2015 Lviv Polytechnic National University.


Reshak A.H.,University of South Bohemia | Reshak A.H.,University Malaysia Perlis | Lakshminarayana G.,Los Alamos National Laboratory | Ebothe J.,University Of Reims | And 5 more authors.
Journal of Alloys and Compounds | Year: 2013

Using FP-LAPW Method we have performed calculations of the band structure of the ZrGa2 and ZrGa3 crystals. The all-electron full potential linearized augmented plane wave method was used to solve the Kohn Sham DFT equations. We have explored different approximations using three kinds of exchange-correlation potentials on the electronic structure and we concluded that there is insignificant influence on the band structure and the density of states. It is clear that there exists a difference in the band dispersion with one move from ZrGa2 to ZrGa3 that is attributed to the fact that ZrGa2 has four formula per unit cell (Z = 4) while ZrGa3 has two formula per unit cell (Z = 2). Despite some similarity in the crystallochemistry of ZrGa2 to ZrGa3 some differences are observed in the band structure dispersion. There is a strong hybridization between the states. The interaction of charges between Zr and Ga atoms is due to the strong hybridization, and the covalent bond arises due to the degree of hybridization. Hence, there is a strong covalent bonding between these atoms. We have obtained a space electron charge density distribution in the average unit cell by calculations of the electron charge density distribution. The space electronic charge density contour distribution is illustrated in (1 0 0) and (1 1 0) planes. © 2012 Elsevier B.V. All rights reserved.


Sichevych O.,Max Planck Institute for Chemical Physics of Solids | Sichevych O.,National University of Forestry and Wood Technology of Ukraine | Krellner C.,Max Planck Institute for Chemical Physics of Solids | Krellner C.,University of Cambridge | And 3 more authors.
Journal of Physics Condensed Matter | Year: 2012

Single crystals of the new ternary compound Ce 2Ga 12Ptwere prepared by the self-flux technique. The crystal structure with the space group P4/nbm was established from single crystal x-ray diffraction data and presents a derivative of the LaGa 6Ni 0.6 prototype. Magnetic susceptibility measurements show CurieWeiss behaviour due to local Ce 3+ moments. At high temperatures, the magnetic anisotropy is dominated by the crystal-electric-field (CEF) effect with the easy axis along the crystallographic c direction. Ce 2Ga 12Ptundergoes two antiferromagnetic phase transitions at T N,1=7.3K and T N,2=5.5K and presents several metamagnetic transitions for the magnetic field along c. Specific-heat measurements prove the bulk nature of these magnetic transitions and reveal a doublet CEF ground state. The 4f contribution to the resistivity shows a broad maximum at T max85K due to Kondo scattering off the CEF ground state and excited levels. © 2012 IOP Publishing Ltd.


Bryn O.,National University of Forestry and Wood Technology of Ukraine
26th International Conference on Wood Science and Technology, ICWST 2015: Implementation of Wood Science in Woodworking Sector - Proceedings | Year: 2015

The possibility of applying conventional flame retardants usually used to improve fire behaviour of wood was evaluated in this study for the production of fire-resistance plywood panels. For making plywood the birch (Betula verrucosa Ehrh.) veneer and commercial phenol-formaldehyde glue resin were used. Five different standardized fire-retardants (-1110, -11, C-13, M-11, C-11) were chosen for veneer impregnation. Firstly, veneer sheets were treated by immersion in 20% aqueous solution of each fire-retardant. Diffusive and capillary methods were evaluated to select the most effective treatment of veneer. Afterwards, five-layer plywood panels were prepared from impregnated and non-impregnated veneers in laboratory press at the following pressing parameters: pressure of 2.0 MPa, temperature of 130°C, time of 10 min, and glue spread of 120 g/m2. Shear strength and fire resistance of plywood were determined. It was found that diffusive method of impregnation of moist veneer, in comparison with capillary method of impregnation of dry veneer, is characterized by the less salting-out of fire-retardants on the veneer surface and their more homogeneous distribution in middle of veneer. It was also found that using of conventional wood fire-retardants for plywood allows to transfer plywood from the group of increased flammability materials to the group of hard inflammable materials. But unfortunately, investigated fire-retardants don't provide the necessary shear strength of plywood panels.

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