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The influence of Narrow Leaved Ash (Fraxinus angustifolia Vahl. ssp. Pannonica Soo & Simon) pre-treatments on the curing behavior of urea-formaldehyde (UF) adhesive was studied. Differential scanning calorimetry (DSC) was used to monitor the curing reaction of UF adhesive mixed with non-treated wood flour (control series) and wood flour of Narrow leaved Ash obtained after different pre-treatments of wood particles. Three different pre-treatments were applied, one with sodium carbonate solution (0.03 g/g of dry wood), one with acetic acid solution (0.06 g/g of dry wood) and one with distilled water. The curing reaction of different adhesive systems showed no apparent differences in peak temperature values, and there were no significant differences in the enthalpy of the reaction. However, it was assessed that the activation energy has lower values for the UF systems with alkaline and acid treated wood flour (76.64 and 76.92 kJ/mol) in regard to the UF systems with control (untreated) wood flour and water treated wood flour (79.28 and 79.14 kJ/mol). In addition, the application of iso-conversional models have shown different curing behavior of UF adhesive systems.

Particles of beech wood were treated with hot water at the temperature of 150 oC, during 60 min, prior to the pelleting process. The applied hot water pretreatment affected the chemical composition and heating value of particles. Two groups of pellets, designated as PT 10 and PT 20, were produced from treated beech particles, with the moisture content of particles being 10.5 and 20.5 %, respectively. Pellets from nontreated beech particles (PNT) served as controls to assess the hot water pretreatment effects on the pellet properties. Both, the applied pretreatment, and the particle moisture content, affected properties of the obtained pellets. The heating value of PT 10 ad PT 20 pellets has increased for ~6 and 1 %, respectively. The mineral (ash) content in treated pellets decreased for about 24 % in comparison to that in PNT pellets. In addition, the bulk (apparent) density of pellets has increased for 21 % (PT 10) and 10 % (PT 20), as a consequence of the hot water pretreatment of particles. The specific density of PT 10 pellets was for 16 % higher, while the equilibrium moisture content (after conditioning at RH 68 % and 20.1?C) was for about 32 % lower in comparison to the respective properties of PNT pellets.

The basic motive of this work is the ever more pronounced need for fire-resistant plywood. In this work, beech veneers have been impregnated with solutions of chosen fire retardants, which are diammonium phosphate monoammonium phosphate, sodium acetate, water glass, sodium tetra borate and boric acid. To determine the preliminary level of fire retardancy achieved in veneers before manufacturing of finished plywood, thermo gravimetric (TG) and derivative thermogravimetric (DTG) methods are used. TG and DTG analyses of treated and untreated wood, as well as of fire retardants alone, were performed on a Perkin-Elmer TGS-2 thermo gravimetric equipment. Fire resistance of plywood was tested in accordance with standard test for resistance to the effects of fire and the most efficient fire retardants monoammonium phosphate and sodium tetra borate, had the same results as TG/DTG analyses, which points out the validity of TG methods in predicting success of fire retardants in future products