Compression strength-focused properties of wood composites induced by structure

Compression strength-focused properties of wood composites induced by structure. The aim of the following study was to examine the contractual compression strength and modulus of elasticity when compressing (MOEC) of three different wood composites with various structure types: softwood (coniferous) plywood, OSB and laminated particleboard 24 mm thick. The biggest MOEC value was performed by the particleboard laminated 24 mm MOEC equalling 70.00 N/mm2. The second was found by the OSB panels, equalling 63.03 N/mm2. Last, but with MOEC value close to OSB, was softwood plywood with MOEC of 62.44 N/mm2. The lowest compression strength was observed by OSB samples, with a value of 2.75 N/mm2. The second lowest value has been performed by coniferous plywood (2.80 N/mm2). The highest compression strength occurred by the particleboard laminated 24 mm, equalling 3.31 N/mm2. Density shares and density profiles of the samples were also analysed, all of the examined composites performed U-shaped density profile The results of the study showed that there is no significant correlation between density and obtained parameters under compression. Observation of density share let the Authors conclude conversely than the results showed. It is supposed that the key factor affecting the compression performance of samples was the adhesive area and solid glue content within the composites. It is assumed that the bigger total contact surface of wood particles coated with adhesive resin, so the sum of the effective (gluing particles) surfaces of the adhesive joint is the better mechanical properties can be performed. This is why the laminated particleboard gave the best mechanical properties, while the worst were observed by the softwood plywood.

Compression strength-focused properties of wood composites induced by density

Compression strength-focused properties of wood composites induced by density. The aim of this study was to analyse the contractual compression strength and modulus of elasticity under compression of ten commercially available wood composites of various thickness, density, structure and surface finish. Density and density profiles have also been performed. The tests showed that there is no significant dependence of the compression strength and MOEC on the density of composites.

Composites from Recycled and Modified Woods—Technology, Properties, Application

The intention of efficient processing and use of less valuable wood species, bio-damaged logs, sawmill residues, cuttings, chips, sawdust, recycled wooden products, and other lignocellulosic raw materials in the production of wood composites is the focus of several scientific research institutes in the world [...]

Theoretical Analysis of Structural I-beams Using Various Types of Transparent Wood

In this article, a numerical analysis of various types of I-beam with web from transparent wood was performed and compared with standard OSB board and glass web. Properties of transparent plywood which have not yet been produced from new kinds of transparent wood samples were calculated using laminate theory. Results of analysis show, that the transparent wood composites prove to be very promising structural material for future use within the load-bearing structures of buildings. The best properties showed the transparent wood composites infiltrated by cellulose nanofibers (CNF) and polyvinyl alcohol (PVA).

Synthesis and characterization of biopolyols through biomass liquefaction of wood shavings and their application in the preparation of polyurethane wood composites

The sustainability of production systems in wood processing, wood industry, and wooden waste disposal is an important issue for European industry and society. Proper development of products based on renewable wood resources gives an opportunity to provide materials with long-term environmental, social, and economic sustainability. This study aims to establish a new way of forestry and agricultural waste materials utilization by synthesis of bio-based polyols and manufacturing of polyurethane wood composites (PU-WC). The first part of this paper describes the liquefaction of wood shavings at a temperature of 150 °C for 6 h in three different solvents—glycerol, poly (ethylene glycol) and their mixture in a 1:1 ratio. The second part deals with the synthesis of polyurethane (PU) resins containing 90% of biopolyol. Eight sets of materials with different NCO:OH ratios were obtained in a one-step method using a hydraulic press. These materials were characterized, and the material with the most promising properties was selected for polyurethane wood composites production. Composites with 40%, 50%, 60%, and 70% of wood shavings were obtained. The addition of filler caused an increase in flexural strength, Young`s modulus, hardness, and impact strength. Scanning electron microscopy (SEM) showed good adhesion between the polymer and the filler. The optimum filler content is between 50 and 60% by weight of the composite. The presented study provides a significant step toward a greener alternative for materials produced mainly from non-renewable resources.

The Influence of Drying Temperature on Color Change of Hornbeam and Maple Wood Used as Surface and Inner Layers of Wood Composites

The thermal treatment of wood changes its structure due to the degradation of wood polymers (cellulose, hemicellulose and lignin), so the physical properties of wood are either improved or degraded. Color changes apply not only to natural wood, but also to such wood composites for which some amount of glue is used in their construction (e.g., plywood, blockboard or laminboard). This article is focused on the analysis of hornbeam and field maple wood color changes influenced by drying temperature. Two types of drying modes were used: hot-air mode where the temperature of the drying environment was 60 °C, and high-temperature mode with a drying temperature of 120 °C. The drying mode was divided into two phases depending on the moisture content of the wood. The compared woods had similar values of color coordinates at the beginning of drying. During hot-air drying, the largest changes in color coordinates occurred during the first 24 h. The total color difference between the color at the end and the beginning of drying was 7.3 for hornbeam and 11.1 for maple. The overall color difference between the compared woods was minimal. During high-temperature drying (120 °C), the color changes of the dried woods were more pronounced. In the case of maple wood, there was a very significant change in color and the value of ΔE* was twice as high as for hornbeam. The total color difference between the color at the end and at the beginning of drying was 8.7 for hornbeam and 18.9 for maple.

Additive Manufacturing of Wood Composite Panels for Individual Layer Fabrication (ILF)

The renewable resource, wood, is becoming increasingly popular as a feedstock material for additive manufacturing (AM). It can help make those processes more affordable and reduce their environmental impact. Individual layer fabrication (ILF) is a novel AM process conceived for structural applications. In ILF, parts are formed by laminating thin, individually contoured panels of wood composites which are fabricated additively by binder jetting. The individual fabrication of single panels allows the application of mechanical pressure in manufacturing those board-like elements, leading to a reduction of binder contend and an increase of mechanical strength. In this paper, the ILF process is described in detail, geometric and processing limitations are identified, and the mechanical properties of the intermediate product (panels) are presented. It is shown that the thickness of panels significantly influences the geometric accuracy. Wood composite panels from spruce chips and pMDI adhesive showed flexural strengths between 24.00 and 52.45 MPa with adhesive contents between 6.98 and 17.00 wt %. Thus, the panels meet the mechanical requirements for usage in the European construction industry. Additionally, they have significantly lower binder contents than previously investigated additively manufactured wood composites.