Otpornost prema izvlačenju vijaka i međuslojna čvrstoća troslojne ploče vlaknatice s grubim vlaknima u središnjem sloju

Screw withdrawal resistance (SWR) and surface soundness of three-layer MDF were investigated and the results were compared to the single-layer MDF. For this aim, effects of various formulation variables such as coarse fiber length (24.4 to 4.3 mm), resin content (10.5 to 6.5 wt%) in the core layer, average panel density (730 to 650 kg/m3), and surface/core layer ratio (70/30 to 30/70) were determined. The face and edge SWR and surface soundness of three-layer MDF panels were determined according to EN 320 and EN 311 standards, respectively. The results showed that the face SWR and edge SWR of MDF panels improved as the fi ber length increased from 4.3 to 11.5 mm in the core layer. Similar results were determined for the surface soundness. The surface soundness of MDF panels improved with increasing fiber length in the core layer up to 17.8 mm. SWR and surface soundness improved with increasing resin content in the core layer, shelling ratio, and panel density.U radu je prikazano istraživanje otpornosti prema izvlačenju vijaka i međuslojne čvrstoće troslojne MDF ploče, a rezultati su uspoređeni sa svojstvima jednoslojne MDF ploče. Za tu su svrhu istraživani učinci različitih parametara na pripremu ploče, primjerice duljina grubih vlakana (24,4 – 4,3 mm) i sadržaj smole (6,5 –10,5 %) u središnjem sloju, prosječna gustoća ploče (650 to 730 kg/m3) i omjer površinskoga i središnjeg sloja (70/30 – 30/70). Otpornost prema izvlačenju vijaka na licu i rubu ploče te međuslojna čvrstoća ispitivane su prema normama EN 320 i EN 311. Rezultati su pokazali da se otpornost prema izvlačenju vijaka na licu i rubu ploče povećala s povećanjem duljine vlakana u središnjem sloju s 4,3 na 11,5 mm. Slični su rezultati utvrđeni i za međuslojnu čvrstoću. Naime, međuslojna se čvrstoća MDF ploča također povećala s povećanjem duljine vlakana u središnjem sloju sve do 17,8 mm. Otpornost prema izvlačenju vijaka i međuslojna čvrstoća ploča povećale su se i s povećanjem udjela smole u središnjem sloju, omjera površinskoga i središnjeg sloja te gustoće ploče

Physical and mechanical properties of nanoreinforced particleboard composites

Novel composite materials having desired performance properties can be developed by nanotechnology. The major objective of this research was to produce nanomaterial-reinforced particleboard composites with enhanced physical and mechanical performance. Urea formaldehyde adhesive used to produce particleboard composites was reinforced with nanoSiO2, nanoAl2O3, and nanoZnO at loading level of 0%, 1%, and 3%. To evaluate physical properties density, thickness swelling, water absorption, and equilibrium moisture content were determined while modulus of rupture, modulus of elasticity, bonding strength, and screw withdrawal strength tests were carried out to evaluate mechanical properties of the particleboard composites. The results acquired in this work revealed that nanomaterial reinforcement technique significantly affected the physical and mechanical performance properties of the particleboard composites. The findings showed that the modulus of rupture, modulus of elasticity, bonding strength, and screw withdrawal resistance of the composites improved by all the nanomaterials used in this study, except 3% nanoZnO. It was also determined that using 1% nanoSiO2 or 1% nanoAl2O3 in the composites had the best results in the bonding strength and screw withdrawal resistance. The findings indicate that it is possible to produce novel wood composites by using proper nanomaterial type and loading level

Performance characterization of plywood panels bonded with melamine-urea-formaldehyde resin and cellulose nanofibril/borax as an additive

In this study, different loading levels of cellulose nanofibril and borax were added as reinforcement in melamine-urea-formaldehyde adhesive to enhance the performance properties of plywood panels as engineered wood composites. Physical properties (density, thickness swelling, water absorption, and moisture content), mechanical properties (modulus of rupture, modulus of elasticity, and bonding strength), and formaldehyde content were tested using relevant standards. The results showed that cellulose nanofibril and borax had a synergistic effect, resulting in improved physico-mechanical properties. The best results were obtained by combining 3 % cellulose nanofibril and borax. It was determined that the combination of cellulose nanofibril and borax reinforcement resulted in a significant improvement of around 15 % in the thickness swelling, water absorption, and moisture content of plywood panels. The combination of cellulose nanofibril and borax reinforcing resulted in a significant increase of around 26 % in the modulus of rupture and modulus of elasticity of plywood panels, with a bonding strength of around 47 %. The reinforcement technique did result in a 34 % decrease in free formaldehyde content. As a consequence, cellulose nanofibril and borax can be used as effective additives in the production of plywood panels to enhance their performance properties

Influence of press type on the technologıcal propertıes of partıcleboard

Bu çalışmada 280x210x1.8 cm boyutlarında, 0.68 g/cm3 yoğunlukta, üre formaldehit tutkalı kullanılarak yatık preslenmiş yonga levhalar üretilmiştir. Yonga levhaların preslenmesinde sürekli (kontinyu) ve klasik (katlı) olmak üzere iki çeşit pres makinesi kullanılmıştır. Üretilen levhaların eğilme direnci, elastiklik modülü, yüzeye dik çekme direnci, vida tutma gücü ve 24 saatte kalınlığına şişme oranları belirlenmiştir. Yapılan deneyler sonucu pres çeşidinin yonga levha teknik özellikleri üzerinde etkili olduğu saptanmıştır.In is study, particleboard produced in 280x210x1.8 cm dimensions, at 0.68 g/cm3 density with using urea formaldehyde adhesive. For the pressing of the boards, classic press (discontinue) and continue press were used. Static bending strength, modulus of elasticity, internal bond, screw holding and thickness swelling in 24 h immersion were recorded during the experiments. It was stated that press type affected the technological properties of particleboar

Utjecaj brušenja na svojstva površine MDF ploče

The objective of this research was to investigate the effects of sanding on the surface properties of the medium density fiberboard (MDF) panels made from Rhododendron ponticum L. wood. The MDF panels were sanded with different sizes of the sand paper grit: 60-, 60+80- or 60+80+120-grit. Surface absorption and surface roughness of the MDF panels were determined based on EN 382-1 standard and ISO 4287 by using a fi ne stylus profi lometer, respectively. Sessile water drop technique was used to determine contact angle values of the panel surface. The results indicated that sanding process improved the surface smoothness of the panels. However, the wettability and surface absorption of the panels were negatively affected by increasing grit size. The MDF surface sanded with 60-grit size had a lower contact angle, more wettable surface, compared to those that were sanded with 60+80+120-grit size. For example, the average contact angle value of the panels sanded with 60-grit sandpaper was 43.3° as compared to the panels sanded with 60+80+120-grit sand paper which was 76.1°. The rougher surface was more wettable and absorbent compared to smoother surface. Based on the fi ndings obtained from the present study, sanding has a signifi cant effect on the wettability, surface roughness, and surface absorption of the MDF panels, which could provide useful information on the bonding and finishing of the MDF panels.Cilj je istraživanja bio ispitati utjecaj brušenja na svojstva površine srednje gustih ploča vlaknatica (MDF ploča) proizvedenih od drva rododendrona (Rhododendron ponticum L.) MDF ploče brušene su brusnim papirima različitih granulacija: 60, 60+80 ili 60+80+120. Određena su apsorptivna svojstva prema normi EN 382-1 i hrapavost površine MDF ploča prema normi ISO 4287 uz pomoć finog profilometra. Za određivanje kontaktnog kuta površine ploča primijenjena je metoda ispitivanja s kapljicom vode. Rezultati istraživanja pokazuju da brušenje pozitivno utječe na glatkoću površine ploča. Međutim, povećanje granulacije brusnog papira negativno utječe na kvašenje i apsorpciju površine ploča. Površina MDF ploča brušenih brusnim papirom granulacije 60 imala je manji kontaktni kut i bolje kvašenje u usporedbi s površinom koja je brušena brusnim papirima granulacije 60+80+120. Na primjer, srednja vrijednost kontaktnog kuta ploča brušenih brusnim papirom granulacije 60 bila je 43,3°, a ploča brušenih papirom granulacija 60+80+120 bila je 76,1°. Hrapavija površina imala je bolje kvašenje i apsorpciju nego glatkije površine. Na temelju rezultata dobivenih istraživanjem može se zaključiti da proces brušenja ima znatan utjecaj na kvašenje i hrapavost te na apsorptivna svojstva površine MDF ploča, što je osobito važno za proces lijepljenja i površinske obrade brušenih površina

Wettability and surface roughness characteristics of medium density fiberboard panels from rhododendron (rhododendron ponticum) biomass

Wettability and surface roughness properties of medium density fiberboard (MDF) panels made from Rhododendron biomass were examined in this study. Rhododendron dominates the understory layer of the forests throughout the Black Sea Region in Turkey with substantial biomass potential. This study was conducted to evaluate suitability of Rhododendron fiber for MDF production. For the experiments, rhododendron and commercially-manufactured-chip (Pinus sylvestris L. and Quercus robur L.) with 11% moisture content were used. The mixing ratios of rhododendron with commercially-manufactured-chip were 100:0, 75:25, 50:50, 25:75 and 0:100 %, respectively. Commercial urea formaldehyde (UF) adhesive was used as a binder. A stylus method was employed to evaluate the surface characteristics of the samples. Roughness measurements by the stylus method were taken perpendicularly to the fiber. There was a significant diff erence (p=0.05) between surface roughness parameters (Ra, Rz, Rq, and Ry). Th e results obtained in this study revealed that all the panels have met the general purpose-use requirements of European Norm (EN). It was found that panels made with a 25/75 ratio of rhododendron to commercially-manufactured-chip had a significantly lower contact angle (88.14o) than panels made with a 100/0 ratio (117.91o). Surface roughness measurements are based on four roughness parameters, average roughness (Ra), mean peak-to-valley height (Rz), root mean square roughness (Rq), and maximum peak-to-valley height (Ry) were considered to evaluate the surface characteristics of the panels and supported the above findings as the panels made with a 25/75 ratio had a slightly rougher surface with average values of 2.929 μm (Ra). From the tests performed, we conclude that increasing the rhododendron mixing portion increased surface roughness and decreased wettability. Based on these results, rhododendron biomass could be an alternative raw material for MDF manufacturing