Lijepljene lamelirane ploče kao radne ploče u kuhinji

The present study was conducted to investigate the possibility of using PVA-glued laminated panels in place of conventional kitchen countertops namely 32 mm thick MDF and 38 mm thick particleboard. Three types of glued laminated panels were manufactured by laminating two 16 mm thick MDFs, two 16 mm thick particleboards, and three 12 mm thick particleboards at a pressure of 3 MPa , a temperature of 25 0C and variable pressing times of 20, 30, and 40 minutes. Bending and shear strengths, water absorption, and thickness swelling of the laminates were measured and compared with a 32 mm thick MDF and 38 mm thick particleboard. The results indicated that the glued laminated panels remained more dimensionally stable compared to the conventional kitchen countertops. Particleboard laminates had improved bending and shear strengths compared to 38 mm thick particleboard. The results of this study demonstrated that PVA-glued laminated panels could be used as kitchen countertops.Istraživanje prikazano u radu provedeno je s ciljem ispitivanja mogućnosti uporabe lamelirane ploče lijepljene PVA ljepilom umjesto konvencionalnih kuhinjskih radnih ploča,MDF ploča debljine 32mm i iverica debljine 38 mm. Tri tipa lijepljenih lameliranih ploča proizvedena su od dvije MDF ploče debljine 16 mm, dvije ploče iverice debljine 16 mm i tri ploče iverice debljine 12 mm pri tlaku prešanja 3 MPa i temperaturi 25 oC, uz promjenjivo vrijeme prešanja od 20, 30 i 40 minuta. Mjerene su čvrstoća savijanja i čvrstoća smicanja, apsorbcija vode te debljinsko bubrenje lamelirane ploče i uspoređeno sa svojstvima MDF ploče debljine 32 mm i iverice debljine 38 mm. Rezultati su pokazali da su lijepljene lamelirane ploče dimenzionalno stabilnije od konvencionalnih kuhinjskih ploča. Lamelirana ploča od iverice imala je bolju čvrstoću savijanja i smicanja od ploče iverice od 38 mm. Rezultati istraživanja pokazuju mogućnost uporabe lameliranih ploča lijepljenih PVA ljepilom za kuhinjske radne ploče

Otpornost prema vremenskim utjecajima topolovine premazane vodenom otopinom organosilana u nanoveličinama

The potential use of organosilane nanomaterials (nano-zycosil and nano-zycofil) for improving the weathering resistance of poplar wood was evaluated in comparison to common clear coatings (nitrocellulose and polyester lacquer). A 250 μm coating layer was applied by an automatic fi lm applicator at the speed of 150 mm/s. The coated specimens were exposed to a 1000 W xenon arc light source at 65 % relative humidity and temperature of 20 ºC inside a weather-o-meter for 1440 hrs. Among coating materials, nano-zycosil showed the best performance to improve the weathering resistance. Compared to the lacquer-coated samples, the roughness of nanoparticle-coated ones was less affected by weathering. Contact angle measurements indicated that nanozycosil coating had a pronounced decreasing effect on the surface wettability. The combined analyses of SEM and EDX demonstrated that the nanoscale silane layer covered the whole wood surface homogeneously, whereas nitrocellulose and polyester coatings were deposited preferentially in the surface depressions.U radu je prikazano istraživanje mogućnosti uporabe organosilana u nanoveličinama (nano-zycosil i nano-zycofi l) za povećanje otpornosti topolovine na vremenske utjecaje u usporedbi s uporabom klasičnih prozirnih premaznih materijala (nitroceluloznoga i poliesterskoga premaza). Sloj premaza od 250 μm nanesen je strojno, brzinom 150 mm/s. Premazani su uzorci 1440 sati bili izloženi izvoru svjetlosti ksenonske svjetiljke od 1000 W pri relativnoj vlazi zraka od 65 % i na temperaturi od 20 °C. Od premaznih materijala nano-zycosil se pokazao najboljim za povećanje otpornosti na vremenske utjecaje. U usporedbi s uzorcima obrađenim klasičnim premaznim materijalima, hrapavost nanopremaza bila je manje uvjetovana izlaganjem vremenskim utjecajima. Mjerenja kontaktnog kuta pokazala su da premaz nano-zycosilom znatno utječe na smanjenje kvašenja površine. Kombinirane analize SEM i EDX potvrdile su da sloj silana u nanoveličini ravnomjerno prekriva površinu drva, dok je sloj nitroceluloznoga i poliesterskog premaza u udubljenjima na površini deblji

Mjerenje sila rezanja piezoelektričnim dinamometrom tijekom piljenja drva tračnom pilom

Optimization of wood cutting conditions can decrease the cutting forces, which directly relates to the energy consumption. The aim of this study was to measure cutting force components in bandsaw processing of green oak and beech wood at 90°-90° cutting direction (mode A). For this purpose, a piezoelectric dynamometer (KISTLER type 9257A) mounted on the log carriage of vertical bandsaw machine (ESTERER model EB 1400) was used to measure the parallel, normal and lateral cutting forces for different cutting speeds (20, 30 and 40 m s-1) and feed rates (20, 30 and 40 m min-1 ). Results showed that all cutting force components change by increasing the cutting speed and feed rate over the analysed range. However, little changes were observed for lateral force. Overall, oak wood required greater cutting forces compared to beech wood. Conclusively, in the studied range,with increasing cutting speed ratio to feed rate, main cutting force and normal force were decreased.Optimizacijom uvjeta rezanja drva mogu se smanjiti sile rezanja čija veličina izravno utječe na potrošnju energije tijekom piljenja. Cilj istraživanja bio je odrediti sastavnice sile rezanja tijekom piljenja svježe hrastovine i bukovine tračnom pilom, uz smjer rezanja 90° - 90° (mod A). U tu svrhu piezoelektrični je dinamometar (Kistler tip 9257A) montiran na posmična kolica za trupce vertikalne tračne pile (ESTERER model EB 1400) i upotrijebljen za mjerenje paralelne, okomite i bočne sile rezanja pri različitim brzinama rezanja (20, 30 i 40 m·s-1) i posmičnim brzinama (20, 30 i 40 m·min-1). Rezultati su pokazali da se sve sastavnice sile rezanja mijenjaju s povećanjem brzine rezanja i posmične brzine u istraživanom rasponu. Male promjene zabilježene su za bočnu silu. Rezultati su pokazali da su za piljenje hrastovine potrebne veće sile rezanja nego pri piljenju bukovine. Zaključno, u promatranom se rasponu brzina s povećanjem omjera brzine rezanja i posmične brzine smanjuju glavna i okomita sastavnica sile rezanja

Mass transfer in medium density fiberboard (MDF) modified by NA+ montmorillonite (NA+MMT) nanoclay

The potential use of nanoclay was examined to modify fluid transfer properties of medium density fiberboard (MDF). For this, Na+ montmorillonite (Na+MMT) nanoclay was added to urea formaldehyde resin to produce MDF. Then, the air permeability and mass diffusivity of MDF were evaluated. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) confirmed a dispersion and exfoliation of Na+MMT in the modified MDF. The air permeability presented a systematic decrease with increasing nanoclay amount. This reduction agreed with the simple "tortuous path" model. The nanoclay had no effect on the mass diffusivity

The potential use of organosilane water soluble nanomaterials as water vapor diffusion retarders for wood

The retarding effect of organosilane water soluble nanomaterials (nano-zycosil and nano-zycofil) on water vapor diffusion through poplar wood (P.nigra) was evaluated in comparison with that of clear coatings (sealer and nitrocellulose lacquer and polyester lacquer) using cup and sorption methods.  Two drying methods were applied to dry the nanomaterials -coated substrates: oven drying at temperature of 103 ± 2 °C for 24 h. and climatically drying at temperature of 25 °C and relative humidity of 65% for 20 minutes. The results showed that both coating materials decreased the water vapor diffusion rate through the wood. The sealer and nitrocellulose lacquer coating represented a stronger effect on the diffusion coefficient of wood compared to the other coatings. In this case, the nano-zycosil represented a better performance compared to the nano-zycofil. Furthermore, the drying method of the nanomaterials -coated substrates can impact the nanomaterials performance. The water vapor diffusion through the oven-dried substrates was faster than that through the climatically dried ones

Decay resistance of wood impregnated with monoethanolamine and sodium bisulfite pulping black liquors

The efficacy of monoethanolamine and sodium bisulfite pulping black liquors at three concentrations of 1; 1,5 and 2% on the preservation of poplar wood from white rot (Trametes versicolor) was investigated. The wood specimens were impregnated with the black liquors using a full-cell method. The black liquors enhanced the decay resistance without any reduction in mechanical strength, and a remarkable increase was observed at higher concentrations and weight gain percentage. The performance of monoethanolamine black liquor was more pronounced, probably due to lower kappa number and higher pH. The durability class of specimens impregnated with 2% monoethanolamine and sodium bisulfite black liquors improved from 5 (not durable) to 1 (very durable), and from 5 to 3 (moderately durable), respectively. Chemical analysis showed that the presence of additional lignin in wood alters the white rot. Results of anatomical studies showed that the fibers of the control and impregnated wood specimens were collapsed after 16 weeks of incubation. Leaching tests confirmed that the fixation of black liquors in wood should be examined for further studies.   PDF XM

The efficiency of Pistacia atlantica gum for increasing resistance of rapeseed oil-heat treated wood to fungal attacks

In this research, we used Pistacia atlantica gum during cooling phase of oil-heat treatment of poplar wood (Populus deltoids) to improve its resistance to the white-rot fungus Trametes versicolor and growth of the mold fungus Penicillium expansum. Thermal modification was carried out using rapeseed oil at 180 °C, 200 °C and 220 °C for 2 hours and 4 hours. The modified wood specimens were then directly cooled in the oil containing 0 %, 5 % and 10 % (w/w) of the gum at 25 °C for 30 minutes. The chemical constituents of the essential oil extracted with a Clevenger type apparatus were determined by chromatography–mass spectrometry (GC-MS). The amounts of α-pinene, β-pinene and α-terpinolene of the essential oil were 60,2 %, 8,7 % and 3,9 %, respectively. The mold resistance was greatly improved, while the improvement against the decay fungus was only observed for the specimens modified at 180 °C. Our results confirmed that the enhanced fungal resistance was not only due to the presence of monoterpenes in the essential oil, but also to a further reduction in the hygroscopicity of the treated wood

INTER-TRACHEID AND CROSS-FIELD PITTING IN COMPRESSION AND OPPOSITE WOOD OF

Inter-tracheid and cross-filed pit pairs in compression and opposite wood of Norway spruce (Picea abies) were examined. The size, appearance, and frequency of bordered pits on the radial side of axial tracheids and their aperture specification were studied. The type, size, and number of half-bordered pits between the axial tracheids and rays per cross-field were also studied. Several techniques were employed for the measurements: Environmental Scanning Electron Microscope (ESEM), Scanning Electron Microscope (SEM), Light Microscope (LM), and the Frankling method (FM). The structure, size, and frequency of both types of the pits varied between compression and opposite wood. Fewer pits of a smaller size and a smaller aperture diameter were observed in compression wood. The uniseriate arrangement of bordered pit pairs, unpitted tracheid walls, circular- or often slit-like pit aperture, dominantly piceoid but sometimes cupressoid and occasionally taxodioid cross-field pitting, and a number of fissures on the tracheid walls and bordered pits were characteristics of compression wood

Investigation on the heat transfer and evolution of temperature gradient through wood during drying; Case study: beech (Fagus orientalis) and spruce (Picea abies)

The heat transfer through three orthotropic directions and the evolution of temperature gradient in beech (Fagus orientalis) and spruce (Picea abies) during drying were investigated. Thus, due to low capacity of dryer, small flat-sawn boards with dimensions of 80 × 25 × 40 mm (L×R×T) were used. Then, the boards were dried at the dry-bulb temperature of 60 °C and relative humidity of 50 %. Four surfaces of the boards were coated by polyurethane-coated aluminum foil to confine the heat flux along one direction. Then, the boards were thermally insulated by 50 mm-thick Styrofoam. Some holes with 1mm in diameter were made on the board specific distances to measure the temperature using thermocouple. The results showed that the temperature of each wood increased as heating up progressed until it reached to the wet-bulb temperature. Then, it remained at an almost constant value as the wet bulb temperature until the wood moisture content reached the hygroscopic range. Furthermore, the pattern of the temperature profile for both wood species was almost identical. The surface temperature of the boards increased until it reached the dry-bulb temperature of 60 °C, while the core temperate remained as the wet-bulb temperature (48-52 °C) throughout the rest of drying period

Microscopic investigation on the effects of wood surface modification with sol-gel method on the quality of polyurethane and alkyd coatings

In this research, the effects of poplar wood surface modification using sol-gel method on the quality of alkyd and polyurethane coatings for outdoor application were studied. For this purpose, the wood surface was modified with Tetraethoxy‌silane (T) sol-gel material. Then, solvent-borne alkyd (AS) and solvent-borne polyurethane (PS) coatings were applied. The quality of coatings was evaluated by microscopic observation using fluorescence, confocal laser scanning microscopy (CLSM) and EDX-SEM. The results of EDX showed a noticeable silicon peak in the sol-gel-treated specimens. The results of fluorescence microscopic studies showed that alkyd and polyurethane coatings only present in the cell lumens but the sol-gel penetrates into the cell walls. Laser microscope results showed that the modification of wood surface with sol-gel process reduces the roughness of alkyd and polyurethane coatings caused by weathering