PAPER making! g! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® Volume 9, Number 3, 2023
voids. This results from the complexity of strand distribution within the panel and impacts panel performance greatly. In this research, X-ray microcomputer tomography was used to investigate the void characteristics of OSB panels with different structures. The results indicated that OSB panels have a porosity profile opposite to that of density. Unidirectionally oriented homogeneous boards showed slightly higher total porosity, a steeper porosity profile, and higher void size than other three-layer boards. Still, there was no significant difference between them. Although the changes in bending properties resulted from changes in core layer strand orientation, the slight difference in internal bond and water absorption rate was caused by the narrower void distribution and a larger void size. Panels containing a mixture of black spruce and aspen strands had a higher porosity, a steeper porosity profile, and a small void size compared to panels with black spruce strands. This resulted in better bending properties, worse internal bonding, and a lower water absorption rate and thickness swelling. Thus, the internal bond, water absorption rate, and thickness swelling of the panels with a mixed spruce-aspen core layer decreased with an increase in core layer proportion. An opposite trend was observed for panels with a black spruce core layer. Physical and Mechanical Properties of High-Density Fiberboard Bonded with Bio- Based Adhesives, Aneta Gumowska & Grzegorz Kowaluk & Grzegorz Kowaluk, Forests , 14(1), 84 (2023). The high demand for wood-based composites generates a greater use of wood adhesives. The current industrial challenge is to develop modified synthetic adhesives to remove harmful formaldehyde, and to test natural adhesives. The scope of the current research included the manufacturing of high-density fiberboards (HDF) using natural binders such as polylactic acid (PLA), polycaprolactone (PCL), and thermoplastic starch (TPS) with different resination (12%, 15%, 20%). The HDF with biopolymers was compared to a reference HDF, manufactured following the example of industrial technology, with commonly used adhesives such as urea-formaldehyde (UF) resin. Different mechanical and physical properties were determined, namely modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding strength (IB), thickness swelling (TS), water absorption (WA), surface water absorption (SWA), contact angle, as well as density profile; scanning electron microscope (SEM) analysis was also performed. The results showed that increasing the binder content significantly improved the mechanical properties of the panels in the case of starch binder (MOR from 31.35 N mm −2 to 40.10 N mm −2 , IB from 0.24 N mm −2 to 0.39 N mm −2 for dry starch), and reduces these in the case of PLA and PCL. The wet method of starch addition improved the mechanical properties of panels; however, it negatively influenced the reaction of the panels to water (WA 90.3% for dry starch and 105.9% for wet starch after 24 h soaking). Due to dynamically evaporating solvents from the PLA and PCL binding mixtures, a development of the fibers’ resination (blending) techniques should be performed, to avoid the uneven spreading of the binder over the resinated material.
Technical Abstracts
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