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Recent reports indicate that the development of electricity generation using wind turbines will continue to grow. Despite the long service life of wind turbine blades, their technological life comes to an end at a certain point. Currently, there is no industrial method for recycling them, and the proposed solutions need to consider a complete and comprehensive approach to this material. In many countries, these blades are stored in special landfills and await proposals for rational recycling. It has been proposed that this recyclable yet still troublesome raw material be used in building sheathing boards. Sheathing boards used in the construction industry have a relatively long lifecycle. Three types of polymer chips and two resins, i.e., PF and MUF, were used in the study. The boards' quality was assessed per the standards specified for particle boards. The resulting boards were characterized by strengths above 20 N/mm2 and an elastic modulus close to 4000 N/mm2. Slightly better results were obtained with the MUF resin. [ABSTRACT FROM AUTHOR]

The production of plywood from impregnated veneers allows a wood-based product protected in the entire cross-section to be obtained. The conducted research was focused on the properties of veneers impregnated with a mixture of potassium carbonate and urea, such as pH, wettability, colour change and surface roughness. In addition, the properties of plywood produced with melamineurea-formaldehyde resin, such as the shear strength and formaldehyde emission, were the subject of research as well. It was found that the impregnated veneers were characterized by an increased pH, increased wettability, a completely different colour and unchanged surface roughness. Moreover, the impregnation of the veneers caused a decrease in the bonding quality of the plywood and a reduction in formaldehyde emissions from the finished product. It can be concluded that the melamine-urea-formaldehyde adhesive is more suitable for the production of fire-resistant plywood than the urea-formaldehyde adhesive. [ABSTRACT FROM AUTHOR]

Glulam beams are increasingly used in the construction industry because of their high strength and the possibility of using round timber with smaller cross-sections. The load-bearing capacity of beams is strongly related to the quality of the outer layers and, in the case of wood, especially the tension zones. For these reasons, this study decided to replace the outer lamella with tensile plywood. The produced beams were subjected to static bending strength and modulus of elasticity evaluation. It was shown that the best static bending strength values were obtained for beams containing plywood in the tension layer. However, the change in structure in the tension zone of beams made of glued laminated timber results not only in an increase in the load capacity of elements produced in this way but also in a decrease in the range/range of the obtained results of bending strength. This way of modifying the construction of glued laminated beams allows a more rational use of available pine timber. [ABSTRACT FROM AUTHOR]

Engineered wood products (EWP) such as glulam beams are gaining more and more popularity due to several advantages resulting from the wood itself, as well as the constant search for structural materials of natural origin. However, building materials face some requirements regarding their strength. Thus, the study aimed to assess the static bending strength of structural beams produced with the use of pine wood, after the periodic loading of approximately 80 kN for a year. The manufactured beams differed in the type of facing layers, i.e., pine timber with a high modulus of elasticity and plywood. The produced beams, regardless of their structure, are characterized by a similar static bending strength. Moreover, it has been shown that the loading of beams in the range of about 45% of their immediate capacity does not significantly affect their static bending strength and linear modulus of elasticity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Numerous studies have shown that the geometry of micro-joints significantly affects the strength of the so joined timber element. The bending strength increases by creating a larger bonding area by increasing the length of the wedge joint. Although this type of joint has been successfully used for many years, it can still be troublesome to make. For these reasons, the present study investigated an easy-to-fabricate wedge joint, which we folded during the beams' formation and glued with the same adhesive as the individual lamellas. Although the research has not fully answered all the questions relevant to both scientific and technological curiosity, it indicates the great potential of this solution. Following the principle adopted in the ongoing wood optimisation work, we concluded that the beams of the target cross-section should be produced, and it should only be possible to cut them to a certain length. In this approach, we only removed defects at critical points for the beam structure and, in this way, up to 30% of the timber processed could be saved or better utilised. [ABSTRACT FROM AUTHOR]

This study examined the effect of applying cellulose nanoparticles as a filling material for phenol-formaldehyde (PF) resin in the process of manufacturing water-resistant plywood. Based on investigations that concerned the rheological behavior of resin mixture containing various amounts of nanofiller, the modification of resin resulted in a major increase of viscosity. Although Fourier transform infrared spectroscopy did not fully explain the effect of modification on the chemical structure of the adhesive, there was a noticeable improvement in the morphology of cured nanocellulose-reinforced resin. Based on the bonding quality results, the optimum amount of nanocellulose was 3 PBW (parts by weight) per 100 PBW of resin and it allowed the achievement of a notable increase in shear strength values. Moreover, introduction of cellulosic nanoparticles had a positive effect on mechanical properties such as bending strength and modulus of elasticity. In summary, the research showed that it is possible to apply nanocellulose as a modifier for the adhesives in the process of manufacturing water-resistant plywood. [ABSTRACT FROM AUTHOR]

This study examined the manufacture of flat-pressed wood plastic composites (WPC) using rape chips glued with polymeric diphenylmethane diisocyanate (pMDI). Manufactured boards were of 5-ply type, with 30% polyethylene (PE) content in individual layers. The following properties were assessed: modulus of rupture (MOR); modulus of elasticity (MOE); internal bonding strength (IB); thickness swelling (TS) after 24 hours; water absorption (WA); and noise reduction effectiveness. The tests revealed better physical and mechanical properties of polymer-particle boards than similar polymer and rape boards. It was also demonstrated that a change in mechanical properties of polymer and lignin-cellulose boards is strongly associated with polymer location in individual board layers, and that greater porosity of wood material ensures better polymer anchoring in its structure, when compared with rape straw particles. [ABSTRACT FROM AUTHOR]

Various flours were added as fillers for urea-formaldehyde (UF) resin, and effects on the rheological behavior and the curing properties of the resin were evaluated. The plywood properties such as bonding quality, bending strength, modulus of elasticity, and formaldehyde-release were tested. Five types of flours were used, i.e., rye flour, hemp flour, coconut flour, rice flour, and pumpkin flour. The type of flour had a major influence on the properties of resin mixture such as gel time, solid content, and viscosity. The use of rye and pumpkin flour resulted in a longer gelling time, and the adhesive mixture filled with rice flour did not attain the desired viscosity value needed for the production of plywood. The best mechanical properties and bonding quality were achieved by addition of pumpkin flour. However, the bonding quality of plywood glued with an adhesive filled with every other flour retained good values exceeding 1 N/mm² as required by the standard EN 314-2 (1993). The use of hemp flour as a filler for UF resin led to a substantial decrease of free formaldehyde content. [ABSTRACT FROM AUTHOR]

It was determined how the impregnation of birch veneers with a mixture of potassium carbonate and urea affected the fire protection properties, shear strength, modulus of elasticity and modulus of rigidity of plywood glued with PF and UF resin. Veneers were impregnated by soaking in aqueous fire retardant solutions with concentrations of 20% and 30%. Measurements of mass loss, burned area and time of ignition showed the fire protection provided to be very effective. Impregnation did not significantly affect the modulus of elasticity or modulus of rigidity of the plywood. Impregnation caused a decrease in bonding quality, especially in the case of plywood with UF resin soaked in water. For the samples with PF resin, both immersed and boiled in water, impregnation had less impact on the shear strength: its values exceeded 1 N/mm2, thus meeting the requirements of EN 314-2. [ABSTRACT FROM AUTHOR]

Long fibers from fast growing hemp (Cannabis sativa L.) were used as a raw material for the production of insulation boards in this preliminary work. Hemp fiber boards with densities that ranged from 300 kg/m3 to 1100 kg/m3 were studied. The boards were pressed as one- or three-layered structures. In the three-layered structure, the core was formed of hemp fibers and the outer layers were manufactured from 1.5-mm thick birch veneers. The basic insulation properties of the boards were tested. The heat transfer coefficient value for the boards without veneers allowed this material to be classified as an insulating material. Although the additional veneer layers significantly impaired the heat transfer coefficient, its value was still lower than that of standard wood-based board materials with a similar density. The produced boards were characterized as having good noise reduction properties. The acoustic insulation factor was higher compared with boards intended to be used as thermal insulation, such as mineral wool or light fiberboards with four times greater thicknesses. [ABSTRACT FROM AUTHOR]

The dimensional stability of oriented strand boards (OSB) was evaluated in terms of the changes in their length, static bending strength, and modulus of elasticity. Outer layers of these boards were manufactured from particles other than strand chips. The boards were exposed to an air relative humidity of 30%, 65%, or 85%. Dimensional alterations were determined separately for absorption (from 65% to 85% RH) and desorption (from 65% to 30% RH) changes. Changes in the mechanical properties of the boards were evaluated after they underwent two cycles of the conditioning process and were compared with the baseline values. The study implied that relative changes in the mechanical properties and length increased when there was a reduction in the size of chips that formed the outer layers. A linear relationship was established between the relative changes in the board length determined for the axis that was more susceptible to deformation and the modulus of elasticity. These changes were inversely proportional to the value of the modulus of elasticity. [ABSTRACT FROM AUTHOR]

• Thin wood-based honeycomb panels with slander cells were manufactured. • The paper core was impregnated by modified starch. • Failure maps for sandwich panels were prepared. The research results describing damage to wood-based lightweight panels, in which slender core cells are made of paper impregnated with modified starch, have not been encountered yet. Such solutions can benefit the circular economy era, especially in the automotive and furniture industries. The research aimed to develop failure mechanism maps for thin-walled sandwich panels consisting of wood-based facings separated by a honeycomb core of paper impregnated with modified starch. For this purpose, beams with three different facings and two types of core in two directions of orthotropy were subjected to three-point bending. It was verified that the thickness of the facing determines the strength and stiffness of the honeycomb panels, that the impregnation of the core with modified starch causes a slight deterioration in the strength and stiffness of the beams, and that the dominant type of beam failure is shear damage to the thin-walled core. There were no cases of damage to beams as a result of face indentation or face yielding. [ABSTRACT FROM AUTHOR]

This study evaluated the possibility of producing oriented strand boards (OSB) from non-strand chips. Properties of the produced boards were compared with commercially available OSB/3. Research has shown that replacing the strand chips of external layers with smaller chips allowed for the manufacturing of OSB/3 using chips up to four times shorter than standard strand chips. Oriented strand board manufacturers should consider preparing a new standard and introducing the market to a new type of OSB with very good mechanical properties and made of selected strand chips comprising one of the fractions obtained during screening. [ABSTRACT FROM AUTHOR]

This study evaluated the possibility of producing low-density oriented strand boards (OSB) from industrial chips of Pinus sylvestris L. Statistical analysis was used to determine the lowest possible density of resulting OSBs meeting the requirements of EN standard 300 for type 3 boards. The analysis revealed that this type of board could be obtained with a density as low as 425 kg/m³, corresponding to a compression ratio of about 0.85 for pine wood. An important parameter was the quality of the pine chips, the dimensions of which should be as close as possible to the dimensions of standard wood strands. [ABSTRACT FROM AUTHOR]

This study investigated the mechanical, physical, and thermal properties of three-layer particleboards produced from annual plant straws and three polymers: polypropylene (PP), high-density polyethylene (HDPE), and polylactic acid (PLA). The rape straw (Brassica napus L. var. Napus) was used as an internal layer, while rye (Secale L.) or triticale (Triticosecale Witt.) was applied as an external layer in the obtained particleboards. The boards were tested for their density, thickness swelling, static bending strength, modulus of elasticity, and thermal degradation characteristics. Moreover, the changes in the structure of composites were determined by infrared spectroscopy. Among the straw-based boards with the addition of tested polymers, satisfactory properties were obtained mainly using HDPE. In turn, the straw-based composites with PP were characterized by moderate properties, while PLA-containing boards did not show clearly favorable properties either in terms of the mechanical or physical features. The properties of straw–polymer boards produced based on triticale straw were slightly better than those of the rye-based boards, probably due to the geometry of the strands, which was more favorable for triticale straw. The obtained results indicated that annual plant fibers, mainly triticale, can be used as wood substitutes for the production of biocomposites. Moreover, the addition of polymers allows for the use of the obtained boards in conditions of increased humidity. [ABSTRACT FROM AUTHOR]

The study investigated the possibility of using rape straw and expanded polystyrene for the production of low density particleboards. Particleboards with the core layer made of wood chips or rape straw, partly substituted with polystyrene (7%), were manufactured within the density range of 500 - 650 kg/ m3, and resinated with MUF resin. Our study confirmed that wood chip-expanded polystyrene (WP) and wood chip-rape straw-expanded polystyrene boards (WRP), of density reduced to 600 kg/m3, met the mechanical requirements of the subject standard for boards intended for interior design (including furniture) and used in dry conditions. However, further density reduction required an increased resination of the core layer. [ABSTRACT FROM AUTHOR]

This study concerns the influence of selected fungi on changes in physical and mechanical properties of type P2 particleboards intended for use in dry conditions. The tested fungi included Aspergillus niger van Tiehgem, Chaetomium globosum Kunze et Fr., Trichoderma viride Persoon ex S.F., Gray aggr., and Penicillium funiculosum Thom. The incubation process lasted for 16 weeks, yet samples for the strength test were selected after a period of four weeks. The degradation level of boards was estimated by measuring the decrement of initial mass and changes in physicomechanical properties. The obtained results showed that mechanical strength of the investigated boards affected by the tested fungi decreased by 15% to 20%. However, the differences in DSC thermographs indicate that it is cellulose that mainly undergoes degradation in the wood of the investigated boards. Based on the changes in mechanical properties and DSC analyses, we consider T. viride and A. niger as the most aggressive fungal species. [ABSTRACT FROM AUTHOR]

The study investigates the properties of lightweight (350-550 kg/m³) particleboardsmade using wood or rape particles and with veneers applied to their surfaces. Their suitability for the production of furniture and elements of interior design isdiscussed. Panels with veneer on their faces were made using a "one shot" pressing cycle. It was found that rape particles may be used for the production of lightweight particleboards, and that they are a good alternative to wood chips. Particleboards made of rape straw, covered with beech veneer during the pressing cycle in order to strengthen their subsurface layers, have better properties than the corresponding wood-chip-based particleboards. However, all the boards, throughout the whole density range, meet the requirements for P2 boards, i.e. boards intended for interior decoration and furniture production (MOR 11 N/mm², MOE 1600 N/mm²,IB 0.35 N/mm² according to EN 312). [ABSTRACT FROM AUTHOR]

The main objective of the study was to determine the effect of impregnation of the paper core with acetylated starch on the mechanical properties and absorbed energy in the three-point bending test of wood-based honeycomb panels under varying temperatures and relative air humidity conditions. Nearly six hundred beams in various combinations, three types of facings, three core cells geometries, and two paper thicknesses were tested. The experiment results and their statistical analysis prove a significant relationship between the impregnation of paper with modified starch and mechanical properties. The most effective in absorbing energy, the honeycomb panels, consisted of a core with a wall thickness of 0.25 mm and a particleboard facing. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the static bending strength of pine glulam manufactured when obtaining the main yield, i.e., structural timber or timber to be used in the production of structural glulam. Analyses were conducted on pine timber harvested from three different locations in Poland. Two beam variants were manufactured, differing in the timber arrangement, horizontal vs. vertical. It was shown that the static bending strength of beams manufactured in the vertical timber arrangement variant is slightly higher than that of beams produced from horizontally arranged layers, with the latter beams characterised by a smaller confidence interval for this strength. Moreover, it was found that the difference in the value of the 5th percentile for both beam types is slight and both beam types are considered to exhibit a high bending strength of over 40 N/mm2. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Strand substitution was evaluated for the core of OSB with chips produced by grinding of recycled particleboards and wood waste. All the boards manufactured under laboratory conditions having a share of small chips in the core had high mechanical parameters, thus meeting the requirements of the standard for OSB/3. No significant effect was found of the applied modification of the core on bending strength or modulus of elasticity (MOE) determined for the longer axis. In turn, such properties as modulus of rupture (MOR) and MOE, determined for the shorter axis, as well as internal bond (IB) were rapidly reduced. In the case of boards containing 100% recycled chips in the core, a reduction was found in values of MOR, MOE, and IB by 45%, 30%, and 45%, respectively. In turn, the application of small chips, which previously had not been resinated, makes it possible to manufacture boards with internal bond lower by only 30%, even at the 100% substitution. Application of recycled chips produced by grinding of the P2 type particleboard did not make it possible to manufacture boards meeting the requirements of the standard after the boiling test, irrespective of the amount of small chips added to the core. Boards containing in their core small chips, which previously had not been resinated, had much better properties in this respect, since only in case of 100% substitution the manufactured boards exhibited internal bond after the boiling test lower than the requirements of the standard EN 300. [ABSTRACT FROM AUTHOR]

In this study, the possibility of using adhesives of natural origin for the manufacture of wood fiber-based lightweight panels was investigated. The boards, of a density ranging from 150 to 250 kg/m3, were glued together using commercial urea–formaldehyde resin (control board), solutions of rye flour and potato starch and two types of starch: oxidized and gelatinized. The density and density profile, compressive strength, modulus of elasticity, acoustic properties and thermal conductivity were determined in the produced boards. These studies show that when food components are used as binding agents in the manufacture of lightweight wood fiberboards, the properties obtained can be comparable with those of commercial boards manufactured using synthetic agents. [ABSTRACT FROM AUTHOR]

The paper assessed the feasibility of manufacturing glued structural elements made of pine wood after grading it mechanically in a horizontal arrangement. It was assumed that the pine wood was not free of defects and that the outer lamellas would also be visually inspected. This would result in only rejecting items with large, rotten knots. Beams of the assumed grades GL32c, GL28c and GL24c were made of the examined pine wood. Our study indicated that the expected modulus of elasticity in bending was largely maintained by the designed beam models but that their strength was connected with the quality of the respective lamellas, rather than with their modulus of elasticity. On average, the bending strength of the beams was 44.6 MPa. The cause of their destruction was the individual technical quality of a given item of timber, which was loosely related to its modulus of elasticity, assessed in a bending test. Although the modulus of elasticity of the manufactured beam types differed quite significantly (11.45–14.08 kN/mm2), the bending strength for all types was similar. Significant differences occurred only during a more detailed analysis because lower classes were characterized by a greater variation of the bending strength. In this case, beams with a strength of 24 MPa to 50 MPa appeared. [ABSTRACT FROM AUTHOR]

The study assessed the quality of pine lumber by marking the modulus of elasticity in the horizontal system. The research material was a plank with the following dimensions: 137 mm wide × 39.50 mm thick × 3485 mm long. The pine wood was obtained by sawing timber in the form of logs with round cross sections and originating from the Forest Division Olesno (50°52′30″ N, 18°25′00″ E). Each long log was sawn to provide four logs of about 3.5 m, which were marked as butt-end logs (O), middle logs (S)—2 items, and top logs (W). The origin of the logs from the trunk (Pinus sylvestris L.) has a significant impact on the physical and mechanical properties of the wood from which they are made. Only butt-end logs (log type O) allows for the production of high-quality timber elements. The pine timber that was evaluated in this paper had a high density of about 570 kg/m3 and a high percentage of timber items were assigned to class C24 and higher (above 50%). The adopted horizontal model of evaluation of the modulus of elasticity gave similar results to those obtained in an evaluation according to the EN-408. [ABSTRACT FROM AUTHOR]

The research hypothesis states that the impregnation of the honeycomb paper core of lightweight sandwich panels with modified starch, sodium silicate and epoxy resin (LiquidWood®) resin has a significant effect on its elastic properties. In this study, a recycled paper was used in three thicknesses, seven types of cell shapes, including two after numerical optimization and three types of impregnating agents. The method of digital image analysis determined the elastic constants of manufactured paper cores, which were subjected to axial compression in two directions. Based on the experimental results, elastic constants of the cores were calculated and compared with the results of numerical calculations. It has been shown that each of the impregnating solutions used improved the stiffness of the paper core. The best results were obtained for LiquidWood® epoxy resin and modified starch. An important parameter of cell geometry affecting their rigidity is the angle of the cell wall φ, as well as the arrangement of the common cell wall in relation to the direction of load. The numerical models developed were positively verified. [ABSTRACT FROM AUTHOR]

Due to the fact that impregnation with fire retardant usually reduces the strength of the produced particleboards, this research was carried out to investigate whether it is possible to use phenol–formaldehyde (PF) resin modified using various amounts (0%, 5%, 10%, 15%, and 20%) of polymeric 4,4′-methylene diphenyl diisocyanate (pMDI) for this purpose. The need to optimize the addition of pMDI is particularly important due to health and environmental aspects and high price. Furthermore, the curing process of hybrid resins is still not fully explained, especially in the case of small loadings. Manufactured particleboards differed in the share of impregnated particles (50% and 100%). The mixture of potassium carbonate and urea was used as the impregnating solution. Based on the outcomes of hybrid resins properties, it was found that the addition of pMDI leads to the increase in solid content, pH, and viscosity of the mixtures, to the improvement in resin reactivity determined using differential scanning calorimetry and to the decrease in thermal stability in the cured state evaluated using thermogravimetric analysis. Moreover, particleboard property results have shown that using impregnated particles (both 50% and 100%) decreased the strength of manufactured boards bonded using neat PF resin. However, the introduction of pMDI allowed us to compensate for the negative impact of fire-retardant-treated wood and it was found that the optimal loading of pMDI for the board containing 50% of impregnated particles is 5% and for board made entirely of treated wood it is 10%. [ABSTRACT FROM AUTHOR]

Physical and mechanical properties were evaluated for industrial and laboratory boards intended to be used in the construction industry. The boards were subjected to accelerated aging tests including resistance to humidity in the conditions of cyclic test in accordance with EN 321 (2002), and determination of dimensional changes resulting from changes in relative humidity according to EN 318 (2002). The greatest changes were observed after one test cycle. Moreover, the boards made of fine chips demonstrated slightly higher resistance to the tested factors. Although laboratory boards showed a much lower density, their behavior following the exposure to the assessed factors was similar to that of industrial plates. [ABSTRACT FROM AUTHOR]

The possibility of replacing the rye flour commonly used as a filler for urea formaldehyde resins was investigated for plywood production with birch bark characterized by various particle dimensions. The effects on the curing and rheological properties of the adhesives were investigated. Moreover, the plywood was tested to evaluate the formaldehyde emissions, bonding quality, modulus of elasticity, and bending strength. The results showed that the size of the bark particles had a significant effect on the viscosity of the adhesives but did not affect other properties of the resin. Replacing the flour with the bark significantly decreased the formaldehyde release, but there was no clear correlation with the dimensional fraction of the bark powder. The particle size had notable effects on bonding quality and mechanical properties. The best results were obtained for a sieve with square holes whose inside lengths were 0.315; however, all plywood samples achieved shear strength values exceeding the requirements of EN 314-2 (1993). [ABSTRACT FROM AUTHOR]

The influence of selected technological aspects was studied relative to characteristics of oriented strand lumber (OSL) boards manufactured from pine strands. Six types of boards were prepared, differing in the strand fraction size, density (700 kg/m3 and 800 kg/m3), and adhesive used to glue the strands in the core layer. The adhesives compared were melamine-urea-formaldehyde (MUF) and polymeric diphenylmethane diisocyanate (pMDI). The results showed that the OSL boards had good physical and mechanical properties, even though pine strands of diverse characteristics, particularly in terms of their length and width, were used for their production. The influence of strand size was clear in the results of the bending and elongation tests. Both for the bending test and tensile strength in a direction parallel to the wood grain, the properties were on average 20% greater for boards made of larger strands compared to those made of smaller strands. However, the latter demonstrated greater internal bonding strength (IB). The weakness of OSL boards made from small strands was their low modulus of elasticity, particularly when the board density was simultaneously reduced. [ABSTRACT FROM AUTHOR]

Insulating materials made from straw are becoming increasingly popular in the construction industry. Straw can be used in the construction of buildings as uncompressed straw chips or in the form of compressed panels. This study aimed to determine the possibility of manufacturing boards from straw particles with densities in the range of 150–400 kg/m3, allowing favorable mechanical properties while simultaneously providing high thermal and acoustic insulation properties. The study also analyzed the influence of the degree of carpentry density on the quality of the manufactured boards. The study shows that insulation boards can be produced from straw particles with satisfactory properties already at densities in the range of 200–150 kg/m3. Boards with this density have a compressive strength of 150 kPa, thermal resistance of 0.033–0.046 W/(m·K), and a sound absorption coefficient above 0.31. [ABSTRACT FROM AUTHOR]

This paper investigated the possibility of using very fine wood chips for the production of P5 type building boards according to the EN 312 (2010) standard. Small wood chips are more evenly compressed during mat pressing because they have a high bulk density. Therefore, the beneficial effects of forming denser outer layers is lost. To achieve the desired shape of the density profile curve of a board, the moisture content of the chips used in the outer face layers was increased considerably (up to about 30%). As a result of the conducted tests, the mechanical properties of the manufactured boards met the EN 312 requirements for P5 boards above a density of 650 kg/m³. In cases when the additional conditions are being met, the standard requirements may be met at an even lower density level of approximately 550 kg/m³. [ABSTRACT FROM AUTHOR]

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/m3 and 700 kg/m3 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/mm2. 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/m3, 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. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate the effect of propylamine addition to urea-formaldehyde resin on the properties of resultant plywood. The research consisted in investigating the properties of both liquid and cured resins, as well as the produced plywood. Studies have shown that the incorporation of propylamine adversely affected reactivity of the adhesive mixtures by increasing their pH. The evaluation of adhesive chemical structure with FTIR spectroscopy showed some slight changes indicating the reaction of formaldehyde with introduced modifier. The addition of propylamine contributed to the considerable reduction of free formaldehyde contained in the cured adhesive. Furthermore, the propylamine was also found to work effectively as a formaldehyde scavenger by significantly reducing the hazardous emission from plywood. However, based on the results of bonding quality, delamination, bending strength and modulus of elasticity it was found that application of propylamine resulted in a noticeable deterioration of plywood properties. Therefore, the amount of introduced modifier should not exceed 1% of solid UF resin. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

From modern buildings to public spaces are made of concrete, steel, and glass. These materials increase propagation of sound and the reverberation time. Therefore, furniture should be good sound absorbers in such places. The objective of this study was to ascertain acoustic properties of wood-based materials by determining normal acoustic impedance on the surface and sound absorption coefficients. Experiments were carried out on 17 types of wood-based materials commonly employed in furniture design and manufacture. Investigations were conducted based on the transfer-function method. It was demonstrated that for frequencies between 125 and 500 Hz, the highest capability of sound absorption was determined of low surface layer density and high porosity. Honeycomb panels with paper core absorbed better sounds in the range between 1 and 2 kHz. Panels of considerable external surface irregularities were characterized by the most favorable acoustic properties for the frequency of 4 kHz. [ABSTRACT FROM AUTHOR]

This study evaluates the impact of the number of cycles of the V313 test (EN 321 2002) on the mechanical properties of 15-mm-thick OSB/3 and OSB/4. The obtained results were compared with the properties of the boards exposed to external environmental conditions. The results of the study indicate that the tested boards were characterized with a 50% decrease in static bending strength and a 70% decrease in tensile strength perpendicular to the plane. However, both types of boards met the requirements of the standard (EN 300 2006) with respect to their modulus of rupture. The method of exposing boards to outdoor conditions has a substantial influence on the change of the physicomechanical properties of OSBs. In the boards used in this study, however, those changes occurred slower than those evoked by the V313 test, especially after an upright exposure. For these reasons, for that type of board storage, an equation was determined that can bring the property changes following the V313 test into an acceptable range to allow for the evaluation of the board properties. In the case of vertical exposure, from the second year forward, changes in the properties of the OSB/3 were similar to those presented by the boards demonstrated from the second cycle of the V313 test. [ABSTRACT FROM AUTHOR]

This paper presents the strength properties of wooden trusses. The proposed solutions may constitute an alternative to currently produced trusses, in cases when posts and cross braces are joined with flanges using punched metal plate fasteners. Glued carpentry joints, although requiring a more complicated manufacturing process, on the one hand promote a more rational utilisation of available structural timber resources, while on the other hand they restrict the use of metal fasteners. The results of the conducted analyses show that the proposed solutions at the current stage of research are characterised by an approx. 30% lower static bending strength compared to trusses manufactured using punched metal plate fasteners. However, these solutions make it possible to produce trusses with load-bearing capacities comparable to that of structural timber of grade C24 and stiffness slightly higher than that of lattice beams manufactured using punched metal plate fasteners. The strength of wooden trusses manufactured in the laboratory ranged from nearly 20 N/mm2 to over 32 N/mm2. Thus, satisfactory primary values for further work were obtained. [ABSTRACT FROM AUTHOR]

The study analyzed potential applicability for asymmetric reinforcement of glulam beams using materials with a higher modulus of elasticity. Reinforcement elements included smooth and ribbed steel rods as well as basalt rods. These rods were placed only in the tensile zone, assuming that they will not only impart increased rigidity but first of all will reduce the scatter of bending strength values. What is significant, tests were conducted on timber with defects, as it is most commonly used in industrial practice. Analyses showed that this provides an increase in rigidity close to the assumed level. A significant increase in strength was observed. The manufactured beams reinforced with steel and basalt rods were characterized by mean bending strength amounting to 54 and 47 N/mm2, respectively. However, no significant improvement was found in the scatter of the observed variable. Beams reinforced with steel exhibit a 20% higher strength than unreinforced beams. The lower strength of beams reinforced with basalt bars may be related to the lower modulus of elasticity of the basalt itself. [ABSTRACT FROM AUTHOR]

This study investigates the effects of chip type and sawdust percentage on physical and mechanical properties of chip–sawdust boards. The used wood chips varied in linear dimensions and original source. The origin determined the wood quality, which translated into the chips' linear dimensions. The used materials were chips from sawmill waste processing, aggregate processing of sawmill wood, and chips intended for medium-density boards. The experiment demonstrated that the best boards in terms of mechanical properties were obtained from 4-mm-thick chips with 30% sawdust content and a density of 850 kg/m3. These boards meet the requirements of the EN 312 (2010) standard for P5 boards. [ABSTRACT FROM AUTHOR]

This study examined the effects of selected types of thermoplastics on the physical and mechanical properties of polymer-triticale boards. The investigated thermoplastics differed in their type (polypropylene (PP), polyethylene (PE), polystyrene (PS)), form (granulate, agglomerate) and origin (native, recycled). The resulting five-ply boards contained layers made from different materials (straw or pine wood) and featured different moisture contents (2%, 25%, and 7% for the face, middle, and core layers, respectively). Thermoplastics were added only to two external layers, where they substituted 30% of straw particles. This study demonstrated that, irrespective of their type, thermoplastics added to the face layers most favorably reduced the hydrophobic properties of the boards, i.e., thickness, swelling, and V100, by nearly 20%. The bending strength and modulus of elasticity were about 10% lower in the experimental boards than in the reference ones, but still within the limits set out in standard for P7 boards (20 N/mm2 according to EN 312). [ABSTRACT FROM AUTHOR]

This paper describes an attempt to use long fibres from fast growing hemp (Cannabis sativa L.) as a raw material for the production of boards for the building and furniture industry. Hemp fibre boards with densities of 300 to 1100 kg/m3 were studied. The board surfaces were finished using a one-cycle method in which birch veneers were pressed to make the boards. The pulp was glued with pMDI (9 wt.% based on dry weight). The basic mechanical and hydrophobic properties of the boards were tested. The static bending strength and modulus of elasticity of the boards with a density of about 650 kg/m3 were comparable to P2 furniture boards. Only the higher density boards had adequate properties that met standards for the building industry, which were comparable to those of OSB/3 and MFP boards. Hemp fibre boards were characterised by relatively good water resistance, which was manifested by low swelling and low soaking susceptibility. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine normal impedance on the surface as well as sound absorption coefficients for several wood species from Europe and from the tropical zone. The mathematical models of Miki, Attenborough, and Allard - dealing with acoustic properties of porous materials - have also been compared. The air flow resistivity exhibits a distinct link between fiber dimensions and wood porosity. The highest sound absorption coefficient was found for oak, ash, sapeli, and pine woods at 2 kHz frequency. The Attenborough model provides results closest to laboratory measurements, although it still requires significant improvements. The Miki and Allard models have some drawbacks and should be applied with reservation for the determination of wood acoustic properties. [ABSTRACT FROM AUTHOR]