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Akustyczna płyta komórkowa HDF z rdzeniem falistym oraz sposób wytwarzania płyty komórkowej HDF z rdzeniem falistym
Coffee silverskin and cocoa pod husk modified with methacrylic acid as fillers for the urea-formaldehyde resin in plywood production
Sposób wytwarzania płyt kompozytowych z cząstek lignocelulozowych i polimerów termoplastycznych i płyta wytworzona tym sposobem
The effect of impregnation with fire retardant on the properties of particleboard bonded with PF/pMDI adhesive
Properties of fiber-gypsum composite formed on the basis of hemp (Cannabis sativa L.) fibers grown in Poland and natural gypsum
: Properties of fiber-gypsum composite formed on the basis of hemp (Cannabis sativa L.) fibers grown in Poland and natural gypsum. The popularity of composites reinforced with natural fibers is constantly growing and therefore, they are a subject of many scientific works as well. An example of interesting concept is the use of hemp fibers to reinforce a gypsum matrix and therefore, presented study was aimed to determine the effect of their content on the properties of resultant composites. Moreover, the influence of setting temperature was also investigated. The scope of the research included determination of properties such as: density, setting time, bending strength, modulus of elasticity and thermal conductivity coefficient. Studies have shown that as the amount introduced fibers increases, the density of manufactured composites decreases. Furthermore, increase in the content of hemp causes a significant extension in setting time of the gypsum matrix. Based on the outcomes of mechanical properties, it was found that the optimal content of fibers is 4% and further increase in their share results in a deterioration of flexural strength characteristics. The increase in a setting temperature leads to thereduction in their bending strength and modulus of elasticity. Composites reinforced with hemp fibers demonstrate significantly improved thermal insulation properties
Nanocellulose functionalized with ethylenediamine as a modifier of urea-formaldehyde adhesive in particleboard production
Modified Buckwheat Husk as a Filler for Urea–Formaldehyde Resin in Plywood Production
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.
The Effect of Treatment with Fire Retardant on Properties of Birch Veneer and Manufactured Fire-Resistant Plywood
Propolis extract as a bio-based modifier of urea-formaldehyde adhesive in particleboard production
The effect of pressing parameters and hardener content on the properties of plywood bonded with propylamine-UF adhesive
Current Trends in the Use of Biomass in the Manufacture of Rigid Polyurethane Foams: A Review
This paper discusses methods of using biomass from the agriculture, forestry, food and aquaculture industries as potential raw materials for bio-polyols and as fillers in the production of rigid polyurethane (RPUR) foams. Various aspects of obtaining bio-polyols are discussed, as well as the impact of replacing petrochemical polyols with bio-polyols on the properties of foams. Special attention is paid to the conversion of vegetable oils and lignin. Another important aspect of the research is the use of biomass as foam fillers. Chemical and physical modifications are discussed, and important factors, such as the type and origin of biomass, particle size and amount, affecting the foaming process, microstructure and properties of RPUR foams are identified. The advantages and disadvantages of using biomass in foam production are described. It is found that bio-polyols can replace (at least partially) petrochemical polyols while maintaining the high insulation and strength of foams. In the case of the use of biomass as fillers, it is found that the shaping of their properties is largely dependent on the specific characteristics of the filler particles. This requires further research into process optimization but allows for the fine-tuning of RPUR foam properties to meet specific requirements.
Properties of Particle Boards Containing Polymer Waste
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.
The Influence of Hemp Fibers (Cannabis sativa L.) on the Mechanical Properties of Fiber–Gypsum Boards Reinforcing the Gypsum Matrix
The modern construction industry is looking for new ecological materials (available, cheap, recyclable) that can successfully replace materials that are not environmentally friendly. Fibers of natural origin are materials that can improve the properties of gypsum composites. This is an important issue because synthetic fibers (hardly biodegradable—glass or polypropylene fibers) are commonly used to reinforce gypsum boards. Increasing the state of knowledge regarding the possibility of replacing synthetic fibers with natural fibers is another step towards creating more environmentally friendly building materials and determining their characteristics. This paper investigates the possibility of manufacturing fiber–gypsum composites based on natural gypsum (building gypsum) and hemp (Cannabis sativa L.) fibers grown in Poland. The effect of introducing hemp fibers of different lengths and with varying proportions of mass (mass of gypsum to mass of fibers) into the gypsum matrix was investigated. The experimental data obtained indicate that adding hemp fibers to the gypsum matrix increases the static bending strength of the composites manufactured. The highest mechanical strength, at 4.19 N/mm2, was observed in fiber–gypsum composites with 4% hemp fiber content at 50 mm in length. A similar trend of increased strength was observed in longitudinal tension. Again, the composite variant with 4% fiber content within the gypsum matrix had the highest mechanical strength. Manufacturing fibers–gypsum composites with more than 4% hemp fiber content negatively affected the composites’ strength. Mixing long (50 mm) hemp fibers with the gypsum matrix is technologically problematic, but tests have shown a positive effect on the mechanical properties of the refined composites. The article indicates the length and quantity limitations of hemp fibers on the basis of which fiber–gypsum composites were produced.
Modification of Urea-Formaldehyde Resin with Triethylenetetramine: Effect on Adhesive Properties and Plywood Strength
Due to its multiple amino groups, triethylenetetramine (TETA) can be used as an effective formaldehyde scavenger contributing to the reduction in formaldehyde emission from plywood. This study aimed to evaluate the effect of small TETA loadings on the properties of urea-formaldehyde (UF) resin and the performance of the resulting plywood. Adhesive mixtures containing 0%, 0.5%, 1.0%, and 1.5% TETA were prepared and characterized in terms of pH, viscosity, solids content, and gel time. The incorporation of TETA significantly increased adhesive pH and gel time, while viscosity and solid content were not significantly affected. The analysis of formaldehyde content and spectroscopic and thermogravimetric analyses of the cured adhesives showed reduced formaldehyde content, changes in chemical structure, and enhanced thermal stability at lower temperatures but accelerated degradation at higher temperatures. Formaldehyde emission from plywood was reduced; however, bonding quality and mechanical performance decreased with higher TETA content. Nevertheless, the wet shear strength of all variants exceeded 1 N/mm2. Adhesive formulation containing 0.5% TETA was selected as the optimal variant, providing environmental benefits while maintaining satisfactory plywood performance.
Physico-Mechanical Characteristics of Gypsum–Fiber Boards Manufactured with Hydrophobically Impregnated Fibers
Although gypsum-based building materials exhibit many positive characteristics, solutions are still being searched for to reduce the use of gypsum or improve the physico-mechanical properties of board materials. In this study, an attempt was made to produce gypsum boards with hemp fibers. Although hemp fibers can be a specific reinforcement for gypsum-based board materials, they negatively affect the gypsum setting process due to their hygroscopic characteristics. Fibers impregnated with derivatives based on polyvinyl acetate, styrene–acrylic copolymer and pMDI (polymeric diphenylmethane diisocyanate) were used in this study. Gypsum–fiber boards produced with impregnated fibers showed approximately 30% higher mechanical properties as determined by the 3-point bending test. The positive effect of the impregnates on the hemp fibers was confirmed by FTIR (Fourier-transform infrared spectroscopy) and TG/DTA (thermogravimetric analysis/thermal gravimetric analysis) analysis.
The effect of the tree dieback process on the mechanical properties of pine (Pinus sylvestris L.) wood
As a result of the progressing climate changes, there is an increase in the volume of pine deadwood harvested each year from Polish forests. Its presence is an important part of the forest ecosystem; however, there are some indications that the material obtained from dying trees can be characterized by lower quality and properties. Taking into account the growing issue of tree dieback, the volume of pine wood annually harvested in Poland, and the importance of wooden products from an economic standpoint, preliminary research aimed at recognizing the process and its effect on the mechanical properties was conducted. Model trees in Brzeg Forest District were selected based on the crown defoliation. The properties of wood obtained from trees representing three different categories of soundness were determined according to the relevant standards. Based on the results of density, modulus of elasticity, bending strength, and compressive strength, it was found that there were statistically significant differences in wood quality depending on the condition of the tree. The results were particularly interesting in the case of compressing strength, where a healthy tree of lower density showed a similar strength to a dying tree with a much higher density.
