Costel Barbuta

Tailor made OSB for special application

The purpose of this study was to develop speciality oriented strand board (OSB) with high stiffness for use in products such as engineered wood flooring (EWF). Three-layer oriented strand boards were manufactured from two feedstocks of strands: a mixture of 90% aspen (Populus tremuloides) and 10% of paper birch (Betula papyrifera), and 100% of small diameter ponderosa pine logs (Pinus ponderosa). The OSB panels were manufactured under a factorial design of three resin contents, two density profiles, and three weight ratios for the face and core layers. Tests to determine density, bending modulus of elasticity (MOE), internal bond (IB) and thickness swelling (TS) were performed according to ASTM standard D 1037-06a. The results showed that the higher values of bending MOE for panels made from aspen/birch mixture and ponderosa pine, 8190 and 9050xa0MPa, respectively, were obtained for the same combination of factors. Such high bending MOE values are very close to Baltic birch (Betula pendula) plywood, a product known for its high stiffness. The effect of resin content on IB is more pronounced for panels made from ponderosa pine than panels made from the aspen/birch mixture. Thickness swelling of panels made from ponderosa pine strands is higher than thickness swelling of panels made from a mixture of aspen and birch strands. The results indicate the potential to tailor an OSB for a specific application such as EWF.ZusammenfassungZiel dieser Studie war es, spezielle OSB-Platten mit hoher Steifigkeit zu entwickeln, die für Produkte wie zum Beispiel Doppelböden (EWF) verwendet werden können. Dreischichtige OSB-Platten wurden aus zwei verschiedenen Strands hergestellt: einer Mischung aus 90% Espe (Populus tremuloides) und 10% Papierbirke (Betula papyrifera) sowie aus 100% Kiefernschwachholz (Pinus ponderosa). Die OSB-Platten wurden nach einem Faktorenversuchsplan bestehend aus drei Harzgehalten, zwei Dichteprofilen und drei Masseverhältnissen der Deck- und Mittelschichten hergestellt. Die Dichte, der Biege-Elastizitätsmodul (MOE), die Querzugfestigkeit (IB) und die Dickenquellung (TS) wurden gemäß ASTM D 1037-06a bestimmt. Die Ergebnisse zeigten, dass sich die höheren E-Moduln bei Platten sowohl aus einer Espe/Birken-Mischung (8190xa0MPa) als auch aus Kiefernschwachholz (9050 MPa) bei den gleichen Faktorenkombinationen ergaben. Diese hohen Biege-E-Modul-Werte erreichen nahezu die Werte für Birkensperrholz (Betula pendula), einem Produkt, das für seine hohe Festigkeit bekannt ist. Der Einfluss des Harzgehalts auf die Querzugfestigkeit ist bei Platten aus Kiefernschwachholz stärker ausgeprägt als bei Platten aus Espe/Birken-Mischung. Platten aus Kiefernschwachholz haben eine höhere Dickenquellung als Platten aus Espe/Birke. Diese Ergebnisse belegen das Potential, um maßgeschneiderte OSB-Platten für spezielle Anwendungen wie zum Beispiel Doppelböden herzustellen.

OSB as substrate for engineered wood flooring

Oriented strand board (OSB) is a commodity product subject to market fluctuation. Development of a specialty OSB could lead to a better, and more stable, market segment for OSB. It was demonstrated in a previous study (Barbuta et al. in Eur. J.xa0Wood Prod. 2010), that OSB may be designed to obtain a high bending modulus of elasticity in the parallel direction, close to Baltic Birch Plywood (BBP) in its strongest direction. This study focused on the use of such specialty OSB in the manufacturing of engineered wood flooring (EWF) prototypes, a product that widely uses BBP as substrate in Canada. The performance of these two prototypes (aspen/birch and ponderosa pine) was studied. Five types of substrates: BBP, sheathing OSB, web stock OSB and the two specialty OSB prototypes were used to manufacture EWF. A 3-mm thick sugar maple plank was selected as the surface layer for all constructions. A polyvinyl acetate (PVA) type I adhesive was used to bond the components. The tests in conditioning rooms showed that BBP substrate constructions present the lowest distortion between humid and dry conditions as well as aspen/birch specialty OSB, according to ANOVA. The construction with OSB sheathing, OSB web stock and ponderosa pine OSB substrates showed higher distortion. The PVA type I adhesive led to weak bonding with high-density OSB surface. The results of this study demonstrate the potential of OSB panels to be used as substrate for EWF.ZusammenfassungOSB ist ein Massenprodukt, das Marktschwankungen unterliegt. Die Entwicklung spezieller OSB-Platten könnte zu besseren und stabileren Absatzmöglichkeiten für OSB führen. In einer früheren Studie (Barbuta et al. Eur. J.xa0Wood Prod. 2010) wurde die Möglichkeit aufgezeigt, OSB herzustellen, dessen Biege-Elastizitätsmodul in Faserrichtung nahezu gleich dem von Birkensperrholz (BBP) in seiner stärksten Richtung ist.In der vorliegenden Studie wird die Verwendung von speziellen OSB zur Herstellung von Doppelböden (EWF) untersucht, für die in Kanada überwiegend BBP als Trägerplatte verwendet wird. Die Eigenschaften von zwei Prototypen (Espe/Birke und Ponderosa Kiefer) wurden untersucht. Zur Herstellung der Doppelböden wurden fünf verschiedene Trägerplattentypen verwendet, nämlich BBP, OSB für Wand- und Deckenelemente, OSB für Stege von I-Trägern und die zwei speziellen OSB-Prototypen. Für alle Konstruktionstypen wurde eine 3xa0mm dicke Deckschicht aus Zuckerahorn ausgewählt. Zur Verklebung der Komponenten wurde Polyvinylacetat (PVA) vom Typxa0I verwendet. Klimatisierungsversuche zeigten gemäß ANOVA, dass sich bei Prüfkörpern mit BBP als Trägerplatte sowie bei speziellen OSB aus Espe/Birken-Mischung die geringsten Formänderungen zwischen feuchten und trockenen Bedingungen ergaben. Bei den anderen Prüfkörpern ergaben sich größere Formänderungen. Der PVA-Klebstoff vom Typ I führte zu einer schlechten Verklebung bei OSB-Oberflächen hoher Dichte. Die Ergebnisse dieser Studie belegen das Potential von OSB-Platten für Trägerplatten von Doppelböden.

Long-Term Performance of Engineered Wood Flooring with Oriented Strand Board Substrate

Plywood is widely used as a substrate in engineered wood flooring (EWF) construction. While the Canadian EWF industry largely relies on Baltic birch plywood (BBP), the development of an alternative substrate is clearly desirable. The objective of this study was to evaluate the long-term performance of EWF made with an oriented strand board (OSB) substrate designed to deliver a higher than normal internal bond. Three-layer OSB panels were made from a mixture of 90 percent aspen (Populus tremuloides) and 10 percent paper birch (Betula papyrifera). Three adhesive configurations were used in the manufacture of specialty OSB panels: 100 percent liquid phenol formaldehyde (PF) resin, a mixture of 60 percent liquid PF resin and 40 percent powder PF resin, and 100 percent polydiphenylmethane diisocyanate (pMDI) resin. The performance of these three specialty OSB products was studied. Five types of substrate were used in the manufacture of EWF: BBP, sheathing OSB, and the three specialty OSBs. A polyurethane adhes...

Moisture-induced stresses in engineered wood flooring with OSB substrate

Engineered wood flooring (EWF) is a multilayer composite flooring product. The cross layered structure is designed to give good dimensional stability to the EWF under changing environmental conditions. However, during winter season in North America, the indoor relative humidity could decrease dramatically and generate an important cupping deformation. The main objective of this study was to characterize the interlaminar stresses (σ33, σ13 and σ23) distribution at free-edges in EWF made with an OSB substrate. A three-dimensional (3D) finite element model was used to predict the cupping deformation and to characterize stresses developed in the EWF. The finite element model is based on an unsteady-state moisture transfer equation, a mechanical equilibrium equation and an elastic constitutive law. The physical and mechanical properties of OSB substrate were experimentally determined as a function of the density and moisture content. The simulated EWF deformations were compared against the laboratory observations. For both simulation and experimental results, the cupping deformation of EWF was induced by varying the ambient relative humidity from 50 to 20% at 20°C. A good agreement has been found between the numerical and experimental EWF cupping deformation. The stress distribution fields generated by the model correspond to the delaminations observed on the OSB substrate in the climate room. Delamination in EWF can occur principally under the action of the tension stress or a combination of tension and shear stresses. Finally, simulated results show that the levels of interlaminar stresses are maximal near the free-edges of EWF strips.