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

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

Microscopic investigation of defects in thermally compressed poplar wood panels

The combined effects of temperature and compression on the microstructure of solid-wood panels produced by Aspen (Populus tremula) wood were evaluated. Thermal compression was applied on aspen wood to increase the density for improving its physical and mechanical properties. The solid wood panels with dimensions of 100 mm by 500 mm by 25 mm were hot-pressed by using a laboratory hot press at a temperature of either 150 °C or 170 °C and pressure of either 1MPa or 2 MPa, respectively, for 45 min. Changes in the microstructure were detected by using a light microscope. The microscopic investigations revealed that the wood exhibited much defects in the process conditions of 170 ºC / 2 MPa, and the distribution of defects were not uniform in the growth rings of the wood specimens in the two treatment groups. All defects in cell structure were quite distinct in the beginning and the last parts of the growth rings and the largest damages occurred in the fibers and vessels for the two process conditions. The results indicate that growth ring structure, vessel porosity, and cell wall thickness have a strong effect on wood behavior in various process conditions

Moisture content, vertical density profile and Janka hardness of thermally compressed pine wood panels as a function of press pressure and temperature

The objective of this study was to investigate the effects of press pressure and temperature on the moisture content (MC), vertical density profile (VDP), and Janka hardness of solid wood panels (SWP) made of Pinus sylvestris. Panels with dimensions of 250mm (width) by 500mm (length) by 18mm (thickness) were compressed at temperatures of 120 and 150C using pressures of 50 and 70 bar for 60min in a hot press. Thermal compression at different pressures reduced final MC, increased density, and improved Janka hardness of wood specimens when compared to control specimens. This study indicated that VDP could affect SWP properties by manipulating some production parameters of wood-composite panels and thereby expand the range of applications of SWP

Approaches on primary log breakdown process

Aim of study: Innovations of "primary breakdown process" which is the first step of log sawing process were evaluated with their reasons and results

Effect of thermal modification by hot pressing on performance properties of paulownia wood boards

The goal of this study was to investigate the effects of thermal modification by hot-pressing on the performance properties of paulownia wood boards. The boards were thermally modified by hot-pressing method under different pressure and temperature levels. As two boards for each modification group plus two for unmodified, totally 10 experimental wood boards were prepared in this study. Main density, vertical density profile (VDP), thickness swell (TS), water absorption (WA), moisture content (MC), and hardness tests were carried out to evaluate the performance properties of the thermally modified or unmodified wood boards. The results obtained in this study indicated that surface density of the boards increased with increasing press pressure. The thermal modification negatively affected the TS and WA values of the boards. Hardness values of the wood boards were significantly improved by the thermal modification. The results of this research revealed that the thermally compressing method could be used to improve end-use properties of low-density wood materials made from fast-growing tree species such as paulownia, poplar, eucalyptus etc. Thus low-value wood materials could be converted to value-added products. In addition, sustainable management of natural resources could be achieved by using the thermal modification method. (C) 2012 Elsevier B.V. All rights reserved

Wettability and roughness characteristics of modified wood boards using a hot-press

The aim of this study was to investigate the effect of the thermal modification process by hot-press on the wettability and surface roughness characteristics of the eucalyptus wood boards. The roughness measurements, average roughness (R(a)), and maximum roughness (R(max)) were taken both parallel and perpendicular to the grain using a fine stylus tracing technique. Contact angle measurements were obtained using a goniometer system connected to a digital camera and computer system. The results showed that surface roughness values of the modified wood boards using a hot-press significantly decreased with increasing press pressure and with decreasing temperature. The contact angle measurements indicated that the thermal modification had a significant influence on the surface wettability of the wood boards. Statistical analyses showed significant differences in the surface roughness and contact angle values of the wood boards following thermal modification. The results acquired in this work provide important information for future research and utilization of the thermally modified wood boards. (C) 2011 Elsevier B.V. All rights reserved

CHARACTESISTICAS DA COR DA MADERIA DE PINUS AFETADAS POR COMPRESS\uc3O T\uc9RMICA

The 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\ub0C or 150\ub0C, 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.O objetivo deste estudo foi determinar os efeitos das modifica\ue7\uf5es t\ue9rmicas e prensagem a quente sobre as caracter\uedsticas de cor de madeira de pinus como bio-recursos. As t\ue1buas de madeira com dimens\uf5es de 250 mm de largura por 500 mm de comprimento por 18 mm de espessura foram comprimidas termicamente a uma temperatura de 120\ub0C ou 150\ub0C, a press\ue3o de 5 ou 7 MPa durante 60 min em uma prensa quente. Os resultados obtidos neste estudo mostraram que as caracter\uedsticas de cor das amostras de madeira de pinus foram afetadas pela press\ue3o e temperatura da prensa. A resina de fugas aumentou significativamente o chromacity (a * - b * e 25.99 \u2013 43.18) das amostras de madeira tratada. Compress\ue3o termica causa escurecimento na cor da madeira, o que aumenta em condi\ue7\uf5es de press\ue3o e alta temperatura

CHARACTESISTICAS DA COR DA MADERIA DE PINUS AFETADAS POR COMPRESSÃO TÉRMICA

The 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.O 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°C ou 150°C, 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 resina de fugas aumentou significativamente o chromacity (a * - b * e 25.99 – 43.18) das amostras de madeira tratada. Compressão termica causa escurecimento na cor da madeira, o que aumenta em condições de pressão e alta temperatura