PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® Volume 8, Number 3, 2022
“Combining X-ray CT and DIC to understand the bending strength of OSB”, Wanzhao Li, Donghu Li, Yanjun Duan, Changtong Mei, Jan Van den Bulcke & Joris Van Acker, Construction and Building Materials , Vol.354, 129125 (7 Nov. 2022). Oriented strand board (OSB) is an important engineered wood product manufactured through bonding of wood strands in cross-oriented layers. The bending strength, one of the crucial properties for loadbearing material, of OSB strongly depends on its structural characteristics. To understand the bending strength of OSB, strain distribution was continuously monitored during a three-point bending test using digital image correlation (DIC) and internal structure was recorded before and after bending using X-ray computed tomography (X-ray CT) respectively. Specimens were cut either along the length (L specimens) or width (W specimens) of OSB panels. For all specimens, strain accumulation mainly seemed to occur in the top and bottom layers and then propagate along or across the central layer. Structural changes in the top and bottom layers of L specimens was either strand delamination or snap off, while only snap off is found in W specimens. This is the main reason of high modulus of elasticity (MOE) and modulus of rupture (MOR) of L specimens in comparison to W specimens. High MOR of the specimens is attributed to strain propagation along the central layer, which can absorb energy from loading. Strain propagation across the central layer causes low MOR, resulting from failure of small strands and delamination in the central layer. Different modes of structural change lead to large variability of MOE, MOR and deformation of the specimens even cut from a single OSB panel. Understanding the bending strength contributes to optimizing the production and application of OSB. “Water vapour transmission properties of uncoated and coated wood-based panels”, Antonio Copak, Vlatka Jirouš- 5DMNRYLü9MHNRVODYäLYNRYLü -RVLS 0LNOHþLü Wood Material Science & Engineering , online (2022). Knowing the properties of wood-based building materials is essential for their proper use. Moisture transfer properties of building materials are crucial to proper building design and the prevention of moisture-related problems. In selecting materials for the building, it is important to know their water vapour transmission properties. In this research the water vapour transmission properties of uncoated and coated particleboard, oriented strand board (OSB) and birch plywood were studied using wet cup method and a moisture gradient in the samples was additionally measured. The water vapour transmission rate of free films of three commercial transparent coatings was also studied. Results showed that particleboard had the highest water vapour permeability and that the coatings reduced the water vapour permeability of all tested wood-based panels. Moreover, sanding increased the water vapour permeability of uncoated particleboard and OSB. The moisture gradient in all tested wood-based panels was linear. The highest water vapour transmission rate was recorded for acrylic water-borne coating, followed by polyurethane water-borne coating and the lowest for polyurethane solvent-based coating.
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Technical Abstracts
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