Ismail Aydin

A comparative study on some physical and mechanical properties of Laminated Veneer Lumber (LVL) produced from Beech ( Fagus orientalis Lipsky) and Eucalyptus ( Eucalyptus camaldulensis Dehn.) veneers

Laminated Veneer Lumber (LVL) panels made from eucalyptus (Eucalyptus camaldulensis Dehn.) and beech (Fagus orientalis Lipsky.) veneers were tested for physical and mechanical strength properties in this study. Urea formaldehyde (UF) and Polyvinyl acetate (PVA) adhesives were used for eucalyptus LVL panels and UF adhesive for beech LVL panels. The effect of veneer wood species on some physical and mechanical properties was found statistically significant. Also, different glue species caused the differences in strength properties of LVL panels.ZusammenfassungIn diesem Beitrag werden einige physikalische und mechanische Eigenschaften von Schichtholzplatten, hergestellt aus Buchen- (Fagus orientalis Lipsky.) und Eukalyptusfurnieren (Eucalyptus camaldulensis Dehn.) untersucht. Für die Herstellung von Schichtholzplatten wurden die Buchenfurniere mit UF und die Eukalyptusfurniere mit UF und PVA verleimt. Die Ergebnisse zeigen, dass sowohl die Art des Bindemittels als auch die Holzart der Furniere die Eigenschaften der Schichtholzplatten signifikant beeinflussen.

Formaldehyde Emission, Surface Roughness, and Some Properties of Plywood as Function of Veneer Drying Temperature

ABSTRACT The drying of veneer is an essential part of the veneer-producing process to aid the gluing during the manufacture of the plywood and LVL. Determining the optimum veneer drying temperature without loss of bonding strength is also very important from an industrial viewpoint. Increased temperatures are being used in veneer drying to reduce the overall drying time and increase capacity. In this study, 2-mm-thick rotary-cut veneers obtained from alder (Alnus glutinosa barbata) logs were used as materials. After rotary cutting, veneer sheets were classified into four groups and dried at 20, 110, 150, and 180°C. Three-ply and 6-mm-thick plywood panels were manufactured with urea formaldehyde (UF) adhesive. Surface roughness and color variations of veneer sheets and shear strength, bending strength, equilibrium moisture content, and formaldehyde emission of plywood panels were determined based on veneer drying temperatures. According to the results, the smoothest surfaces were obtained for 20°C drying temperature while the highest values of surface roughness were obtained for 180°C. Total color change value (ΔE*) increased linearly with increasing drying temperature. Shear strength values of plywood panels decreased clearly with increasing veneer drying temperature. While the least bending strength mean value was obtained for 20°C drying temperature, no clear difference was found for bending strength of plywood panels manufactured from veneers dried at 110, 150, and 180°C. Equilibrium moisture content (EMC) of plywood panels decreased with increasing veneer drying temperature and as the veneer drying temperature was increased, formaldehyde emission values of plywood panels increased.

Effect of Wood Preservatives on Surface Properties of Coated Wood

Effect of wood preservatives (waterborne and organicborne) on the performance of surface finishing properties is investigated. Sapwood of scots pine, (Pinus sylvestris L.), oriental beech (Fagus orientalis Lipsky), and chestnut (Castanea sativa Mill.) specimens (300 × 100 × 15 mm along the grain) were impregnated with aqueous solution of 2% CCA, 2% Tanalith E, 1% boric acid, and Immersol aqua. Surface roughness, dry film thickness, adhesion strength, gloss measurement, scratch, and abrasion resistance were determined according to related standards for treated and untreated samples. The results indicated that surface roughness and adhesion strength depended on wood species and the chemical composition of preservatives. Generally, waterborne wood preservatives increased the surface roughness of wood while the organic-based wood preservatives decreased it. The organic-based wood preservatives decreased adhesion but they increased gloss value. Wood preservatives did not affect the scratch resistance which was found to depend on properties of the coating. All the wood preservatives increased abrasion resistance.

Variations in Bending Strength and Modulus of Elasticity of Spruce and Alder Plywood after Steaming and High Temperature Drying

Veneer logs are generally heated in hot water or steam prior to the cutting process in veneering and plywood manufacturing. For economical reasons, the veneers should be dried quickly and without damage. High temperatures shorten drying times. Besides the benefits of log steaming and quick drying of veneers at high temperatures, these processes can be effective on some mechanical, physical and chemical properties of wood. In this study, the effects of the steaming process on logs and veneer drying temperatures on bending strength and modulus of elasticity (MOE) of plywood panels manufactured from spruce and alder veneers were investigated. For this aim, some parts of both wood species logs were steamed for 12 hours before veneer manufacturing while some parts were used unsteamed. Unsteamed and steamed groups of spruce and alder veneers were dried at 20°C, 110°C and 180°C temperatures. The effect of the steaming process on bending strength and MOE was different depending on the wood species. Bending strength and the MOE values of spruce plywood panels increased while both strength values of alder plywood panels decreased after the steaming process. The highest bending strength and MOE values were obtained at 110°C for alder and at 180°C for spruce plywood panels.

Utilization Potential of Waste from Window Joints for Particleboard

The aim of this study was to determine some technological properties of particleboard made from the waste from window joints. The effect of board density, adhesive amount, and paint presence on the properties of particleboard was investigated. Increasing density and adhesive amount significantly improved their mechanical properties and surface roughness, but negatively affected their thickness swelling. Removing of the paint from the particle resulted in better mechanical properties, but poorer (higher) surface roughness values. This treatment did not statistically affect the thickness swelling. Based on the results, it is proved that the waste of window joints has a potential as raw material for the manufacture of particleboard.

The effects of waiting time of alder (Alnus glutinosa subsp. barbata) veneers before drying on shear and bending strength of plywood

(Alnus glutinosa subsp. barbata) veneers before drying, on some properties of plywood, were investigated. Veneers produced at laboratory conditions were divided into four groups considering their waiting time before the drying process. pH and 1% NaOH solubility of these four groups of veneers were determined. No significant differences were found in solubility and pH values obtained from test groups. In addition bending strength, shear strength and formaldehyde emission values of plywood, produced from these veneers, were investigated. While bending strength and formaldehyde emission values of the plywood showed no differences, the shear strength of the plywood produced from veneers immediately dried after production was significantly higher than the one of other groups.

Formaldehyde Release from Plywood Manufactured with Two Types of Urea Formaldehyde Resins after Fire Retardant Treatment of Veneers

In the present study, it was aimed to investigate the formaldehyde release of plywood panels manufactured from beech, poplar, alder and scots pine veneers treated with 5 % aqueous solutions of commonly used fi re retardants: zinc borate, boric acid, monoammonium phosphate and ammonium sulfate. Two types of urea formaldehyde (UF) resin with different free formaldehyde ratios (0.16 % and 0.20 %) in adhesive were used as adhesive. Formaldehyde release of plywood panels was determined according to fl ask method described in EN 717-3 standard. As a result of this study, it was found that formaldehyde release from panels produced by beech, poplar, alder and scots pine veneers treated with zinc borate and boric acid were higher than those of control panels, while lower formaldehyde release was obtained for panels treated with monoammonium phosphate and ammonium sulfate. This is valid for all four wood species. Treatment of monoammonium phosphate and ammonium sulfate caused considerable reduction in formaldehyde emission from manufactured plywood panels. In some usage areas, where high strength properties are not expected, plywood panels manufactured from veneers treated with monoammonium phosphate and ammonium sulfate may be used for reducing formaldehyde release.

Effects of plasma surface treatment on bending strength and modulus of elasticity of beech and poplar plywood

This is a study on the effect of plasma treatment with different gases and plasma intensity on the bending strength and modulus of elasticity of plywood manufactured from beech and poplar. Oxygen (O2) and ammonia (NH3) plasma were applied on the veneer sheets; two plasma intensities were applied on the veneers with 150 and 300 W in the plasma chamber during one minute. Phenol formaldehyde resin was applied on one surfaces of each veneer with approx. 160 g/m2. Bending strength and modulus of elasticity were determined according to EN 310.The effects of plasma surface treatment on chemical structure of the panels were determined with FTIR-ATR analysis. Bending strength of all tested panels slightly and partly increased without statistical significance when applying oxygen plasma. The effect of ammonia plasma treatment on bending strength and was determined by the wood species and the plasma intensity, and it was not uniform. Modulus of elasticity of the panels with oxygen plasma treatment showed in most cases improvement, whereas ammonia plasma pretreated veneers caused lower values compared to the control panels.

BUHARLAMA İŞLEMİ YAPILMIŞ LADİN (Picea orientalis L.) ODUNUNUN BAZI FİZKSEL VE MEKANİK ÖZELLİKLERİNDEKİ DEĞİŞMELER

Bu cali s manin ana amaci hidro-termik i l sem olarak 12 saat sureyle buharlama yapilan ladin ( Picea orientalis L.) odunun fiziksel ve mekanik ozelliklerindeki de g i s melerin belirlenmesidir. Bu maksatla, a g actan alinan tomruk ikiye bolunerek biri kontrol, di g eri ise test icin kullanilmi s tir. Orneklerin denge rutubet miktari, ozgul a g irlik, daralma ve geni s lemeleri yaninda mekanik ozelliklerinden liflere paralel basinc direnci, statik ve dinamik e g ilme direncindeki de g i s meler belirlenmi s tir. Sonuc olarak; hava kurusu ozgul a g irlik, denge rutubet miktari ve radyal yondeki daralma ve geni s leme oranlari buharlama yapilmi s orneklerde daha du s uktur. E g ilme ve s ok direncinde daha fazla olmak uzere buharlanmi s orneklerin mekanik direnc ozelliklerinde azalma olmu s tur.