Triboelektrična i hidrofobna svojstva funkcionaliziranih lignoceluloznih materijala

In the development of sustainable products, lignocellulosic materials with hydrophobic properties can be functionalized and used as reinforcement, especially in bio-composite materials, as well as in various applications such as packaging, water-repellent and self-renewing materials. This study is aimed to improve the surface properties and triboelectric properties of wood materials. Functionalized wood veneers were prepared by impregnating 3 different wood veneers (beech, mahogany and oak) with 5 different chemical solutions (cationic cellulose, cationic starch, polyethyleneimine, sodium alginate and carboxymethyl cellulose). Structural characterization of the functional wood materials obtained was investigated by Fourier-transform infrared spectroscopy (FT-IR) technique, wettability and surface properties were examined by contact angle measurements, and morphological properties were examined by scanning electron microscopy (SEM). The triboelectric properties of the devices prepared using functionalized wood materials were investigated. As a result, it was determined that the hydrophobic properties of wood materials were improved and showed triboelectric properties. It demonstrates that functionalized wood materials can be used to power low-power electronic devices.U razvoju održivih proizvoda lignocelulozni materijali hidrofobnih svojstava mogu se funkcionalizirati i upotrebljavati kao ojačivači u biokompozitnim materijalima ili mogu imati različitu primjenu u ambalaži te u vodoodbojnim i samoobnavljajućim materijalima. Cilj ovog istraživanja bio je pronaći način poboljšanja površinskih i triboelektričnih svojstava drvnih materijala. Za istraživanje je pripremljen funkcionalizirani furnir od tri različite vrste drva (bukovine, mahagonija i hrastovine), impregniran s pet različitih kemijskih otopina (kationskom celulozom, kationskim škrobom, polietileniminom, natrijevim alginatom i karboksimetilcelulozom). Karakterizacija strukture dobivenih funkcionaliziranih drvnih materijala provedena je Furierovom infracrvenom spektroskopijom (FT-IR), kvašenje i svojstva površine istražena su mjerenjem kontaktnog kuta, a morfološka svojstva ispitana su skenirajućim elektronskim mikroskopom (SEM). Nadalje, istražena su triboelektrična svojstva uređaja izrađenih od funkcionaliziranih drvnih materijala. Utvrđeno je da se funkcionalizirani drvni materijali mogu primijeniti za napajanje uređaja male snage

Ispitivanje parametara površinske kvalitete toplinski prešanog drva paulovnije

The aim of this study was to evaluate the effect of thermal compression process on some surface properties of paulownia solid wood materials. The widest surface of wood samples was mechanically compressed at high temperatures. The duration was 45 min. Four different process combinations were created, including two temperatures (150 °C and 170 °C) and two pressure levels (20 bar and 22.5 bar). The surface roughness, wettability and color properties of treated and untreated samples were compared. The roughness properties, both parallel and perpendicular to grain direction, were determined according to JIS B 0601:1994 standard. The contact angle changes of water dripped to the surface were measured according to time. For color properties, a spectrophotometer was used according to CIE L*a*b* system. The color changes were classified according to a grading method from literature. The most remarkable results on wettability were observed. The contact angle values significantly increased with this method. Although higher temperature increased the contact angle values, higher pressures did not change the values. When the surface roughness values were generally considered, this technique could decrease the values up to 40 % ratio according to the control group. Only the combination of 150 °C and 20 bar did not significantly change the values. Lastly, the results of color properties showed that all treatment parameters significantly affected total color change values of samples. Grading results were similar and the color change of modified samples graded as the lowest color difference, except with the combination of 150 °C and 20 bar. The combination of 170 °C and 22.5 bar (highest treatment conditions) significantly changed all color characteristics of samples, except b* parameter. The results of this research showed that mechanical thermal compression method could change surface properties of this fast-growing species.Cilj ovog rada bio je procijeniti učinak toplinskog prešanja na neka površinska svojstva drva paulovnije. Najveća površina uzoraka bila je prešana pri visokim temperaturama. Prešanje je trajalo 45 minuta. Primijenjene su četiri različite kombinacije uvjeta prešanja, uključujući dvije vrijednosti temperature (150 i 170 °C) i dva različita tlaka (20 i 22,5 bara). U eksperimentu su uspoređeni hrapavost površine, kvašenje i boja prešanih i neprešanih uzoraka. Hrapavost je mjerena paralelno i okomito na smjer vlakanaca prema normi JIS B 0601:1994. Mjerena je i promjena kontaktnog kuta vode na površini u vremenu. Boja je određivana spektrofotometrom prema sustavu CIE L*a*b*. Promjene boje klasificirane su primjenom klasifikacijske metode iz literature. Najveće su promjene primijećene među vrijednostima kvašenja. Vrijednosti kontaktnog kuta značajno su se povećale prešanjem. Iako je viša temperatura utjecala na povećanje vrijednosti kontaktnog kuta, veći tlakovi nisu promijenili vrijednosti kontaktnog kuta. Ako se općenito uzmu u obzir vrijednosti hrapavosti površine, upotrijebljena bi tehnika prešanja mogla smanjiti vrijednosti hrapavosti do 40 % s obzirom na kontrolne uzorke. Samo kombinacija od 150 °C i 20 bara nije znatnije promijenila ispitivane vrijednosti. Glede boje, rezultati su pokazali da su svi parametri prešanja bitno utjecali na ukupne vrijednosti promjene boje uzoraka. Rezultati ocjenjivanja boje bili su slični, a promjene boje prešanih uzoraka ocijenjene su kao najmanje, osim za kombinaciju 150 °C i 20 bara. Pogotovo je kombinacija 170 °C i 22,5 bara (najviši parametri prešanja) značajno promijenila sve parametre boje uzoraka, osim parametra b*. Rezultati ovog istraživanja pokazali su da bi metoda toplinskog prešanja mogla promijeniti površinska svojstva drva ove brzorastuće vrste

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

Características da cor da madeira de pinus afetada por compressão térmica

http://dx.doi.org/10.5902/198050989291The goal of this study was to determine the effects of thermal modification and hot-pressing on the colour characteristics of pine wood as bio-resource. The experimental wood boards with dimensions of 250 mm in width by 500 mm in length by 18 mm in thickness were thermally compressed at a temperature of 120˚C or 150˚C, press pressure of 5 or 7 MPa for 60 min in a hot press. Results obtained in this study showed that the colour characteristics of the pine wood boards were affected by press pressure and temperature. The resin leakages significantly increased the chromacity (a* - 25.99 and b* - 43.18) of the treated wood samples. Thermally compressing caused browning of wood colour, which rate increases with pressure at high temperature conditions.http://dx.doi.org/10.5902/198050989291O objetivo deste estudo foi determinar os efeitos das modificações térmicas e prensagem a quente sobre as características de cor de madeira de pinus como bio-recursos. As tábuas de madeira com dimensões de 250 mm de largura por 500 mm de comprimento por 18 mm de espessura foram comprimidas termicamente a uma temperatura de 120 ºC ou 150 ºC, a pressão de 5 ou 7 MPa durante 60 min em uma prensa quente. Os resultados obtidos neste estudo mostraram que as características de cor das amostras de madeira de pinus foram afetadas pela pressão e temperatura da prensa. A exsudação da resina aumentou significativamente as coordenadas cromáticas (a * - b * e 25,99 – 43,18) das amostras de madeira tratada. Compressão térmica causa escurecimento na cor da madeira, o que aumenta em condições de pressão e alta temperatura

Wood-based panels industry in turkey: future raw material challenges and suggestions

World production of wood based panel has grown from 63,1 million cubic meters in 2005 to 75,5 million m3 in 2009, a 12 million m3 rise in production. China is the world’s largest wood based panel’s manufacturer. The Turkish wood based panels industry has shown a tendency of fluctuating during this time. Turkey, as the world’s 4th largest producer of wood based panels, is an important contributor to the industry. Turkey has made great strides in the last 20 years in the forest products industry. Both the development of new materials and techniques of domestic and international market demand have played a decisive role. Turkey’s wood panel production has gone from 100000 m3 in the early 2000s, to 5,5 million m³ of production in 2010. The sector’s total production capacity is approximately 9 million m³. The results obtained thus far indicate that the Turkish wood based panel industry demand for raw material is not being met by the GDF’s chip wood fiber production. Where the raw material supply problem in the industry, as well as the problems encountered in the forest and on the basis of the villagers living adjacent to, not to the time of product problems related to storage and transportation of raw materials and other related problems are bottlenecks. We examine problems related to the provision of raw materials and raw materials research, the need for future estimates of the level at which the world and close to the periphery countries will be examined, wood composite panel production and trade policy recommendations will be developed

Forest resources and sawmill structure of Kosovo: state of the art and perspectives

Professional PaperKosovo, located in the heart of the Balkans, was formerly a part of Yugoslavia. The breakup of Yugoslavia led not only to the creation of new countries and borders; it also had a huge impact on the transportation and availability of raw materials and goods. Kosovo’s forest products industry has been greatly affected by the country’s current political and legal environment. The creation of new boundaries, combined with trade constraints between Kosovo and some neighboring countries, has changed the amount and type of available wood raw material. Although the forest products industry is a very important part of Kosovo’s economy, this change in distribution has had a negative impact on the sawmill structure of the country. To better understand the current state of Kosovo’s forest products sector, data was collected through a survey of all sawmills in Kosovo and through information gathered from the Ministry of Agriculture, Forestry and Rural Development of Kosovo. In this paper, the forest resources and sawmill structure of Kosovo are analyzed and the availability of different species of wood in different regions of the country is presented. Based on these fi ndings, recommendations are provided for further development of the forest and sawmill industryinfo:eu-repo/semantics/publishedVersio

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