In order to improve the acceptance of broader industrial application of flax fiber reinforced beech (Fagus sylvatica L.) plywood, five different industrial applicated adhesive systems were tested. Epoxy resin, urea-formaldehyde, melamine-urea formaldehyde, isocyanate MDI prepolymer, and polyurethane displayed a divergent picture in improving the mechanical properties—modulus of elasticity, modulus of rupture, tensile strength, shear strength and screw withdrawal resistance—of flax fiber-reinforced plywood. Epoxy resin is well suited for flax fiber reinforcement, whereas urea-formaldehyde, melamine urea-formaldehyde, and isocyanate prepolymer improved modulus of elasticity, modulus of rupture, shear strength, and screw withdrawal resistance, but lowered tensile strength. Polyurethane lowered the mechanical properties of flax fiber reinforced plywood. Flax fiber reinforced epoxy resin bonded plywood exceeded glass fiber reinforced plywood in terms of shear strength, modulus of elasticity, and modulus of rupture.
This research presents the influence of two different cellulose (hydrophobic pretreated/non-pretreated) and one flax-fiber unidirectional nonwoven low areal weight fiber reinforcements on the mechanical properties of urea-formaldehyde bonded five layered beech (Fagus sylvatica L.) plywood as an alternative to commonly used synthetic fiber reinforcements. The results display divergent trends regarding the improvement of the mechanical properties—modulus of elasticity, modulus of rupture, tensile strength, shear strength, and screw withdrawal resistance. The non-treated cellulose and flax reinforcing nonwoven fabrics revealed similar mechanical behaviors. The hydrophobic pretreatment of cellulose nonwovens improved the performance of plywood regarding tensile strength (10–11%), shear strength (7–16%), screw withdrawal resistance (11–15%), and modulus of rupture (0–2%), but lowered modulus of elasticity (2–3%) compared to the reference.
Particleboard, engineered wood products as part of a large family of wood composite materials, developed in use mainly in the 1950s and 1960s to utilize inferior wood and wood waste when good-quality wood was in short supply; the annual production capacity worldwide is over 100 million m3. It is also necessary to have a lot of wood raw material for its production, although raw material resources are limited on our planet. In addition to the main wood species, it is therefore possible to think about the wider use of alternative, lesser-known European species of alder, larch, and birch in particleboard production. These three wood species represent an eco-friendly and sustainable wood alternative to the conventional wood raw materials used. This review confirms the diversity of the use of these three species in different fields and proves their suitability in relation to particleboard production. Fundamental research is ongoing in certain universities to determine the proportional shares of use of these tree species in particleboard (in a certain weight proportion in their core layers) for the purpose of formulating the correct technology shares and rules for their application in the wood-based panel industry.
The aim of this study was to create a reinforced composite wood-based panel that would be leaned towards the environment Plywood was used as a core material and fiber-reinforced polymer was used as a reinforcement. Conventional resin for the fiber-reinforced polymer was substituted with polyvinyl acetate (PVAC), which has several advantages, such as a lower price, easier handling, and better degradability. The second chosen component, basalt fiber, is cost attractive and environmentally friendly. The combination of one and two layers of fabric with three fiber fractions and 4 mm thick plywood was investigated. The best results were achieved with two layers of fabric and the highest fiber fraction. The improvements of the ultimate bending load and bending stiffness of the plywood in the perpendicular direction were 305% and 325%, respectively. The ultimate load and stiffness of the parallel direction were improved by 31% and 35%, respectively. However, specimens always failed in the compressional zone. The highest reinforcing effect was found with the impact test: The energy required to fracture specimens increased by 4213% and 6150% for one and two layers of fabric, respectively. In conclusion, specimens exhibited high ductility due to the PVAC and basalt fiber. The amount of work and energy required to cause fractures was extensive.