Nadir Ayrilmis

Variations in compression strength and surface roughness of heat-treated Turkish river red gum (Eucalyptus camaldulensis) wood

This article reports the effects of heat treatment on compression strength parallel to the grain, the surface roughness [average roughness (Ra)], and the air-dry den-sity of wood from the river red gum tree (Eucalyptus camaldulensis Dehn.) planted in Turkey. Eucalyptus wood was heat-treated at temperatures varying from 120° to 180°C for durations of 2–10 h. Samples cut from the heat-treated wood were tested for air-dry density, compression strength parallel to grain, and surface roughness properties. Roughness measurements by the stylus method were made in the direction perpendicular to the fiber. Based on the findings in this study, the results showed that density, compression strength, and surface roughness values decreased with increasing treatment temperature and treatment times. Eucalyptus wood could be utilized by using proper heat treatment techniques without any losses in strength values in areas where working, stability, and surface smoothness, such as in window frames, are important factors.

Effects of Post Heat-Treatment on Surface Characteristics and Adhesive Bonding Performance of Medium Density Fiberboard

A series of commercially manufactured medium density fiberboard (MDF) panels were exposed to a post-manufacture heat-treatment at various temperatures and durations using a hot press and just enough pressure to ensure firm contact between the panel and the press platens. Post-manufacture heat-treatment improved surface roughness of the exterior MDF panels. Panels treated at 225°C for 30 min had the smoothest surface while the roughest surface was found for the control panels. Wettability and the adhesive bonding strength between veneer sheet and panel surface were decreased as post-treatment press temperature increased. A significant relationship (R 2 = 0.92) existed between contact angles and adhesive bond strength.

Evaluation of the physical, mechanical properties and formaldehyde emission of particleboard manufactured from waste stone pine (Pinus pinea L.) cones

The objective of this study was to investigate some physical/mechanical properties and formaldehyde emission of particleboard containing particles of waste stone pine cone at various usage ratios using urea-formaldehyde resin. Some physical (thickness swelling, water absorption), mechanical (modulus of elasticity, modulus of rupture, internal bond strength) properties and formaldehyde emission of particleboards were evaluated. The addition of cone particle improved water resistance of the panels and greatly reduced their formaldehyde emissions. However, flexural properties and internal bond strength decreased with increasing cone particle content in the panel. The cone of the stone pine can be considered as an alternative to wood material in the manufacture of particleboard used in indoor environment due to lower thickness swelling, water absorption and formaldehyde emission.

Flat-Pressed Wood Plastic Composite as an Alternative to Conventional Wood-Based Panels

This study evaluated physical and mechanical properties of the wood plastic composite panels made from dry-blended rubberwood fiber-polypropylene (PP) powder formulations using a conventional flat-press process under laboratory conditions. Three levels of rubberwood fibers (Hevea brasiliensis), 40%, 50%, and 60% based on the composition by weight, were mixed with the PP powder without and with 3% (based on weight) maleic anhydride grafted PP (MAPP) as a coupling agent. Water resistance of the panels was negatively influenced by the increasing wood fiber content. The modulus of rupture of the panels significantly increased with the increase in the wood fiber content from 40 to 50 wt% and then decreased as the fiber content reached 60 wt% but this decrease was not significant. The modulus of elasticity of the panels increased with the increase in fiber content from 40 to 60 wt%. Internal bond strength and screw withdrawal resistance declined with the increase in fiber content from 40% to 60 wt%. The formulations with MAPP were found to have higher strength and better water resistance.

Comparison of some aggregation techniques using group analytic hierarchy process

We presented and employed seven simple group AHP aggregation techniques.The LW-AHP model was a well evaluated group AHP method.For non-homogenous group we suggest to divide the group in smaller homogenous groups.One of our new group methods, the WGM-WAM or the WGM-LW-AHP can be employed. Group decision making is an important part of multiple criteria decision making and the analytic hierarchy process (AHP). The aim of this paper was to compare group AHP methods. Seven simple group AHP aggregation techniques that could be attractive for applications selected from the vast array of group AHP models proposed in the literature were selected for evaluation. We developed three new measures of evaluation: group Euclidean distance, group minimum violations, and distance between weights for the purpose of evaluation. The results of seven group AHP methods of the theoretical example were evaluated by three new evaluation measures, satisfactory index and fitting performance index. Furthermore, a case study of a decision making problem from the construction engineering field was performed and nine group AHP aggregation techniques, seven of them formerly presented and two new two stage group approaches were applied. Finally, the case study was evaluated using all five measures for each of the nine group decision making methods. The results showed that not all group AHP methods are equally convenient and that the selection of the method depended on the specific application.

Surface characteristics and overlaying properties of flat-pressed wood plastic composites

This study evaluated surface characteristics and overlaying properties of wood plastic composite (WPC) panels made from dry-blended rubber wood fiber-polypropylene (PP) powder formulations using a conventional flat-press process under laboratory conditions. Three levels of rubberwood fibers (Hevea brasiliensis), 40%, 50%, and 60%, based on the composition by weight, were mixed with the PP powder without and with 3% (based on weight) maleic anhydride grafted PP (MAPP) as a coupling agent. Contact angle measurements on the WPC samples were performed using a goniometer connected with a digital camera which collected one image per second. Roughness measurements, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Ry), were taken from the sanded samples along and across the sandmarks using a fine stylus tracing technique. With increasing polymer content, surface roughness of the WPC panels improved while their wettability and adhesive bonding strength decreased. The formulations without MAPP were found to have higher surface roughness but they also had better wettability. Wettability and surface roughness of the WPC panels can provide good information on their ability to bond.ZusammenfassungIn dieser Studie wurden die Oberflächen- und Beschichtungseigenschaften von Holz-Polymer-Werkstoffplatten (WPC) untersucht, die aus im Trockenverfahren hergestellten Mischungen aus Gummibaum-Holzfasern (Hevea brasiliensis) und Polypropylen (PP) im Flachpressverfahren unter Laborbedingungen hergestellt worden waren. Drei verschiedene Holzmehlgehalte, 40%, 50% und 60% (Masseprozent), wurden mit PP-Pulver gemischt, und zwar sowohl ohne als auch mit 3% (Masseprozent) mit Maleinsäureanhydrid gepfropftem PP (MAPP) als Haftvermittler. Die Kontaktwinkel auf den WPC-Proben wurden mittels eines Goniometers gemessen, der an eine Digitalkamera angeschlossen war, die eine Aufnahme pro Sekunde machte. Rauheitsmessungen, wurden durchgeführt. Dabei wurden die durchschnittliche Rauheit (Ra), die mittlere Rautiefe (Rz) und die maximale Rauheit (Ry) an den geschliffenen Prüfkörpern in und quer zur Schleifrichtung mittels des Tastschnittverfahrens bestimmt. Mit zunehmendem Polymergehalt nahm die Oberflächenrauheit der WPC-Platten ab, während ihre Benetzbarkeit und die Klebefestigkeit abnahmen. Die Mischungen ohne MAPP wiesen eine größere Oberflächenrauheit, aber auch eine bessere Benetzbarkeit auf. Die Benetzbarkeit und die Oberflächenrauheit von WPC-Platten können zur Beurteilung von deren Verklebungsverhalten herangezogen werden.

Utilization of Waste Tire Rubber in the Manufacturing of Particleboard

Utilization of waste tire rubber in the manufacture of particleboard was investigated, using the same method as that used in the wood-based panel industry. The manufacturing parameters were: a specific gravity of 0.65 and waste tire rubber content (10/90, 20/80, and 30/70 by wt% of waste tire rubber/wood particle). Two resin types, melamine/urea formaldehyde (MUF) and polyisocyanate, were used in the experiments. Average modulus of rupture values of MUF bonded particleboards with rubber crumbs were between 13–58% lower than the average of the control samples while polyisocyanate bonded particleboards were 12–51%. Water resistance of the boards improved with the increase in rubber crumb/wood particle ratio. Thickness swelling values of the MUF bonded particleboards decreased from 14–53% while polyisocyanate bonded particleboards were 9–48% as compared to control samples.

Fire and bending properties of blockboard with fire retardant treated veneers

This study evaluated fire and bending properties of blockboards with various fire retardant treated veneers. Blockboards were manufactured using untreated fir strips and sandwiched between treated ekaba veneers at final assembly. The veneers were treated with either boric acid (BA), disodium octoborate tetrahydrate (DOT), alumina trihydrate (ATH), or a BA/DOT mixture. Modulus of rupture and modulus of elasticity tests were performed according to European Standard EN 310. Blockboards were also tested for fire resistance as indicated by a cone calorimeter. Treatments had little negative effect on flexural strength; flexural stiffness was significantly lower for the highest treatment levels. Treatments resulted in a significant reduction in predicted flame spread rate. ZusammenfassungUntersucht wurden die Abbrand- und Biegeeigenschaften von Tischlerplatten, deren Deckfurniere mit unterschiedlichen Feuerschutzmitteln behandelt worden waren. Die Mittelschicht der Tischlerplatten bestand aus unbehandelten Tannenholzleisten. Die Decklagen bestanden aus imprägnierten Ekaba Furnieren. Die Furniere waren entweder mit Borsäure (BA), Disodium-Oktoborat-Tetrahydrat (DOT), Aluminium-Trihydrat (ATH) oder einer Mischung aus BA und DOT imprägniert worden. Festigkeits- und Steifigkeitsversuche wurden gemäss der europäischen Norm EN 310 durchgeführt. Das Brandverhalten der Tischlerplatten wurde mittels eines Kegel-Kalorimeters abgeschätzt. Die Behandlung der Furniere hatte einen geringen Einfluss auf die Biegefestigkeit, wohingegen die Steifigkeit bei den stärksten Behandlungsstufen signifikant verringert war. Die Imprägnierungen reduzierten die erwartete Flammenausbreitungsgeschwindigkeit signifikant.

Utilization of waste tire rubber in manufacture of oriented strandboard

Some physical and mechanical properties of oriented strandboards (OSBs) containing waste tire rubber at various addition levels based on the oven-dry strand weight, using the same method as that used in the manufacture of OSB. Two resin types, phenol-formaldehyde (PF) and polyisocyanate, were used in the experiments. The manufacturing parameters were: a specific gravity of 0.65 and waste tire rubber content (10/90, 20/80 and 30/70 by wt.% of waste tire rubber/wood strand). Average internal bond values of PF-bonded OSB panels with rubber chips were between 17.6% and 48.5% lower than the average of the control samples while polyisocyanate bonded OSBs were 16.5-50.6%. However, water resistance and mechanical properties of OSBs made using polyisocyanate resin were found to comply with general-purpose OSB minimum property requirements of EN 300 Type 1 (1997) values for use in dry conditions at the lowest tire rubber loading level (10%) based on the oven-dry panel weight. The tire rubber improved water resistance of the OSB panel due to its almost hydrophobic property. Based on the findings obtained from this study, we concluded that waste tire rubber could be used for general-purpose OSB manufacturing up to 10% ratio based on the oven-dry panel weight.

Adhesive characteristics and bonding performance of phenol formaldehyde modified with phenol-rich fraction of crude bio-oil

Commercial phenol–formaldehyde (PF) adhesive was gradually substituted by increasing amount of the phenol-rich fraction (PRF) of crude bio-oil up to 40 wt%. The effect of substitution level of the PRF on the chemical, curing, morphological scanning electronic microscope (SEM), and bonding characteristics of the PF adhesive was determined. The tensile-shear strength of single lap-joint wood specimens bonded with the modified PF adhesives was investigated under indoor and outdoor exposure conditions. The chemical composition of the PRF was investigated using some chromatographic and spectroscopic techniques. Further structural analysis of PRF-modified PF adhesives was determined using Fourier transform infrared spectroscopy (FTIR). The PRF resol had a similar molecular structure to commercial pure phenol resol adhesive. The PRF could be partially substitute for the petroleum-based phenol in commercial PF adhesives with inexpensive phenols derived from lignocellulosic wastes.