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The aim of the presented research was to determine the suitability of both non-modified and modified buckwheat husk (BH) as a filler for urea-formaldehyde adhesive in plywood production. The effect of two modification methods, acetylation and silanization, was investigated. Infrared spectroscopy outcomes confirmed that both acetylation and silanization of the filler had occurred. Based on the results, it was found that the introduction of BH had a significant effect on both the adhesive properties and the characteristics of the manufactured plywood. The application of non-modified husks led to a reduction in viscosity and an extension of the gelation time, and the produced plywood boards were characterized by reduced bonding quality and increased delamination. Modification of the husk surface by acetylation and silanization with 3-aminopropyltriethoxysilane contributed to the noticeable improvement in the resin properties. On the other hand, the improvement in plywood properties, consisting of the increase in bonding quality and reduced delamination, was observed only in the case of the silanized husk. Furthermore, the use of non-modified and acetylated husk did not significantly influence the formaldehyde emission. The reduction in the investigated emission of formaldehyde was observed only in the case of variants containing 15 and 20% of silanized buckwheat husk.

Nowadays, a significant increase in interest in renewable energy sources can be observed. Wind farms have been one of the solutions representing this trend for many years. One of the important elements of windmills is the blades. The data indicate that what to do with the blades after their use is a global problem, and so it is important to find a way to recycle them. Hence, this work aimed to use these blades in the production of wood-based materials. Two fractions of a fragmented blade were used for the tests: a small one and large one. Boards characterized by densities of 650 kg/m 3 and 700 kg/m 3 were produced, in which the assumed substitution of the wood material with a polymer was 20% or 40%. Mechanical properties such as bending strength (MOR), modulus of elasticity (MOE), and internal bond strength (IB) were investigated. The 2S65 variant achieved the highest static bending strength and a modulus of elasticity of 2625 N/mm 2 . The second best result was noted for the 4S65 variant, which was significantly different from the 2S65 variant. In the case of the variants with a density of 700 kg/m 3 , no significant differences were found and their results were significantly lower. Moreover, research on thickness swelling (TS) after 24 h of immersion and water absorption (WA) were also conducted. The obtained results indicate that the manufactured boards are characterized by good physical and mechanical properties.

This work examines the possibility of applying non-modified nanocellulose and nanocellulose functionalized with 3-aminopropyltriethoxysilane (APTES) as a formaldehyde scavenger for commonly used urea-formaldehyde (UF) adhesive. The effect of silanization was determined with the use of Fourier transform infrared spectroscopy (FTIR), flame atomic absorption spectrometry (FAAS), and elemental analysis. Moreover, the ability of cellulosic nanoparticles to absorb the formaldehyde from an aqueous solution was investigated. After homogenization, cured UF adhesives were examined with the use of FTIR, energy-dispersive spectroscopy (SEM-EDS), and the perforator method to determine the content of formaldehyde. Manufactured boards made of rape straw particles and wood particles were tested in terms of their physico-mechanical properties and formaldehyde emission. Studies have shown that the applied method of silanization was effective. Furthermore, in the case of non-modified nanocellulose, no sign of formaldehyde scavenging ability was found. However, the functionalization of cellulosic nanoparticles with APTES containing an amino group led to the significant reduction of formaldehyde content in both the aqueous solution and the UF adhesive. The mechanical properties of both strawboards and particleboards were improved due to the nanocellulose reinforcement; however, no effect of silanization was found. Nevertheless, functionalization with APTES contributed to a decrease in formaldehyde emission from boards, which was not found in the case of the introduction of non-modified cellulosic nanoparticles.

The aim of the presented study was to apply various bark species (birch, beech, maple, pine and spruce) as fillers for urea-formaldehyde (UF) resin in three-layer plywood manufacturing. For this purpose, all types of bark were ground and added to the adhesive mixture. The resultant plywood was subjected to investigations of the following: tensile strength, modulus of elasticity (MOE), bending strength (MOR) and formaldehyde emission. The results indicate a reduction in the tensile strength. Moreover, the lack of significant improvement in strength parameters can be explained by too high a load of the filler (20 wt%). In the case of formaldehyde emissions, a reduction was observed for birch (B-1), beech (B-2), maple (B-3) and pine bark (B-4). In addition, an increase in the emission of formaldehyde was recorded only for spruce bark.

The aim of this study was to apply waste wood particles (WP) with different sizes from primary wood processing as a filler for open-cell PUR foams. For this purpose, various wood particle sizes were added as a filler for polyurethane foams (PUR). The effects of the addition of of 0.05−<0.125 mm, 0.125−<0.315 mm, 0.315−1.25 mm, and >1.25−2.0 of WP to the polyurethane matrix on the density, the kinetics of PUR foaming, the cell structure, and the morphology were investigated. Scanning electron microscope (SEM) and X-ray computer tomography were used. Based on the results, it was found that the addition of WP in the amount of 10% leads to an increase in density with an increase in particle size. The research shows that the morphology of the PUR-WP foam is influenced by its particle size. The difference in the number and size of cells in PUR-WP composites depends on the wood particle size. The addition of dust causes the formation of cells of much smaller sizes; confirmed by SEM images. Moreover, computer tomography clearly demonstrates that the WP are well-dispersed within the foams’ structures., Competing Interests: The authors declare no conflict of interest.

This research evaluated the possibility of using sawmill by-products from the roundwood-processing line in the production of wood-based panels. Due to its number of favorable properties, interesting chemical composition and large reserves resulting from the lack of industrial applications, the research focused particularly on the use of bark. Manufactured variants of boards differed in the proportions of wood chips to bark (70:30, 60:40, 50:50). Moreover, the boards containing only wood chips and a mixture of chips and sawdust were used as references. Urea-formaldehyde adhesive mixed with ammonium nitrate as a hardener was applied as a binding agent for the boards. Based on the mechanical properties (modulus of elasticity, modulus of rupture, internal bonding), physical properties (density, thickness swelling, water absorption) and content and emission of formaldehyde, it was found that it is possible to produce boards characterized by good properties from sawmill by-products without advanced processing. Moreover, the use of bark instead of sawdust in order to increase the homogeneity of the cross-section allows one to obtain panels with significantly lower formaldehyde emission and water uptake.

In this study, the possibility of using sawdust, a by-product of primary wood processing, as a filler (WF) for rigid polyurethane (PUR) foams was investigated. The effects of the addition of 5, 10, 15 and 20% of WF particles to the polyurethane matrix on the foaming process, cell structure and selected physical-mechanical properties such as density, thermal conductivity, dimensional stability, water absorption, brittleness, compressive and bending strengths were evaluated. Based on the results, it was found that the addition of WF in the amount of up to 10% does not significantly affect the kinetics of the foam foaming process, allowing the reduction of their thermal conductivity, significantly reducing brittleness and maintaining high dimensional stability. On the other hand, such an amount of WF causes a slight decrease in the compressive strength of the foam, a decrease in its bending strength and an increase in water absorption. However, it is important that in spite of the observed decrease in the values of these parameters, the obtained results are satisfactory and consistent with the parameters of insulation materials based on rigid PUR foam, currently available on the market.

Engineered wood products, such as glulam beams, attract much attention from the building industry in recent years. Therefore, there is a constant necessity to seek new models of structural beams, which assume the use of outsized sawn wood pieces as an alternative for the standard construction timber. Three variants of glulam beams, composed of the main yield and side boards arranged in various structures, were proposed. Moreover, the usefulness of wedge-jointed, small-sized timber pieces was also investigated. The manufactured beams were tested, in terms of their mechanical properties, such as bending strength, elastic energy, modulus of elasticity, and resilience. The outcomes have shown that the beams manufactured using wedge-bonded timber of lower grade do not deviate considerably from beams produced from homogeneous lamellas. Furthermore, the results of modulus of elasticity, in the case of the three-layered beams composed of both small-sized non-homogenous main yield and side boards, exceeded the requirements from EN 14080. It allowed us to classify the obtained materials as GL 32c, which is the highest grade specified within the standard.

A significant part of the work carried out so far in the field of production of biocomposite polyurethane foams (PUR) with the use of various types of lignocellulosic fillers mainly concerns rigid PUR foams with a closed-cell structure. In this work, the possibility of using waste wood particles (WP) from primary wood processing as a filler for PUR foams with open-cell structure was investigated. For this purpose, a wood particle fraction of 0.315-1.25 mm was added to the foam in concentrations of 0, 5, 10, 15 and 20%. The foaming course of the modified PUR foams (PUR-WP) was characterized on the basis of the duration of the process' successive stages at the maximum foaming temperature. In order to explain the observed phenomena, a cellular structure was characterized using microscopic analysis such as SEM and light microscope. Computed tomography was also applied to determine the distribution of wood particles in PUR-WP materials. It was observed that the addition of WP to the open-cell PUR foam influences the kinetics of the foaming process of the PUR-WP composition and their morphology, density, compressive strength and thermal properties. The performed tests showed that the addition of WP at an the amount of 10% leads to the increase in the PUR foam's compressive strength by 30% (parallel to foam's growth direction) and reduce the thermal conductivity coefficient by 10%.