scholarly journals Functionality of Beech Bark in Adhesive Mixtures Used in Plywood and Its Effect on the Stability Associated with Material Systems

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1298 ◽  
Author(s):  
Roman Réh ◽  
Rastislav Igaz ◽  
Ľuboš Krišťák ◽  
Ivan Ružiak ◽  
Milada Gajtanska ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Urea Formaldehyde ◽  
Wood Processing ◽  
Material Systems ◽  
Adhesive Mixtures ◽  
The Common ◽  
The Stability ◽  
Heating Up

The results of research into utilizing grinded beech bark in order to substitute commonly used fillers in urea formaldehyde (UF) adhesive mixtures to bond plywood are presented in the present study. Four test groups of plywood with various adhesive mixtures were manufactured under laboratory conditions and used for experimentation. Plywood made using the same technology, with the common filler (technical flour), was used as a reference material. Three different concentrations of grinded beech bark were used. The thermal conductivity of the fillers used, viscosity and its time dependence, homogeneity and the dispersion performance of fillers were evaluated in the analysis of adhesive mixture. The time necessary for heating up the material during the pressing process was a further tested parameter. The produced plywood was analyzed in terms of its modulus of elasticity, bending strength, perpendicular tensile strength and free formaldehyde emissions. Following the research results, beech bark can be characterized as an ecologically friendly alternative to technical flour, shortening the time of pressing by up to 27%. At the same time, in terms of the statistics, the mechanical properties and stability of the material changed insignificantly, and the formaldehyde emissions reduced significantly, by up to 74%. The utilization of bark was in compliance with long-term sustainability, resulting in a decrease in the environmental impact of waste generated during the wood processing.

Exploitation of liquefied wood waste for binding recycled wood particleboards

Holzforschung ◽  
2016 ◽  
Vol 70 (12) ◽  
pp. 1135-1138 ◽  
Author(s):  
Dominika Janiszewska ◽  
Iwona Frąckowiak ◽  
Karolina Mytko
Keyword(s):  
Mechanical Properties ◽  
Industrial Waste ◽  
Bending Strength ◽  
Urea Formaldehyde ◽  
European Standard ◽  
Formaldehyde Content ◽  
Wood Processing ◽  
Uf Resin ◽  
Liquefied Wood ◽  
Standard Quality

Abstract Four types of industrial waste from wood processing, namely a mixed hardwood-softwood powder, pine and beech sawdust, and bark were liquefied and tested as binders for particleboards (PB) made of recycled wood. The liquefaction reaction was carried out at elevated temperature with a mixture of solvents from polyhydroxyl alcohols such as glycerine and propylene glycol, and p-toluenesulfonic acid as a catalyst. Then the liquefied woods (LWs) were characterized in terms of their suitability for PB production as a partial substitute for synthetic urea-formaldehyde (UF) resin. The standard properties of PBs such as tensile strength, bending strength and modulus of elasticity, density, moisture content, swelling after 24 h, water absorption, and formaldehyde content were measured. All tests were performed in comparison to a standard PB bonded by UF resin. It was demonstrated that the substitution of UF resin up to 20% of LW did not have a significant effect on the mechanical properties. PB made of recycled wood produced with LW possessed good mechanical properties that meet the European standard quality demands for PBs.

scholarly journals Utilization of Birch Bark as an Eco-Friendly Filler in Urea-Formaldehyde Adhesives for Plywood Manufacturing

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 511
Author(s):  
Roman Réh ◽  
Ľuboš Krišťák ◽  
Ján Sedliačik ◽  
Pavlo Bekhta ◽  
Monika Božiková ◽  
...  
Keyword(s):  
Bending Strength ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Birch Bark ◽  
Gravimetric Analysis ◽  
European Standard ◽  
Scanning Calorimetry ◽  
Wood Processing ◽  
Fagus Sylvatica L ◽  
Positive Effect

The potential of using ground birch (Betula verrucosa Ehrh.) bark as an eco-friendly additive in urea-formaldehyde (UF) adhesives for plywood manufacturing was investigated in this work. Five-ply plywood panels were fabricated in the laboratory from beech (Fagus sylvatica L.) veneers bonded with UF adhesive formulations comprising three addition levels of birch bark (BB) as a filler (10%, 15%, and 20%). Two UF resin formulations filled with 10% and 20% wheat flour (WF) were used as reference samples. The mechanical properties (bending strength, modulus of elasticity and shear strength) of the laboratory-fabricated plywood panels, bonded with the addition of BB in the adhesive mixture, were evaluated and compared with the European standard requirements (EN 310 and EN 314-2). The mechanical strength of the plywood with the addition of BB in the adhesive mixture is acceptable and met the European standard requirements. Markedly, the positive effect of BB in the UF adhesive mixture on the reduction of formaldehyde emission from plywood panels was also confirmed. Initially, the most significant decrease in formaldehyde release (up to 14%) was measured for the plywood sample, produced with 15% BB. After four weeks, the decrease in formaldehyde was estimated up to 51% for the sample manufactured with 20% BB. The performed differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and derivative thermogravimetry (DTG), also confirmed the findings of the study. As this research demonstrated, BB as a waste or by-product of wood processing industry, can be efficiently utilized as an environmentally friendly, inexpensive alternative to WF as a filler in UF adhesive formulations for plywood manufacturing.

scholarly journals Eco-Friendly, High-Density Fiberboards Bonded with Urea-Formaldehyde and Ammonium Lignosulfonate

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 220
Author(s):  
Petar Antov ◽  
Viktor Savov ◽  
Ľuboš Krišťák ◽  
Roman Réh ◽  
George I. Mantanis
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Urea Formaldehyde ◽  
Physical And Mechanical Properties ◽  
High Density ◽  
Thickness Swelling ◽  
Formaldehyde Content ◽  
Uf Resin ◽  
Natural Wood ◽  
European Standards

The potential of producing eco-friendly, formaldehyde-free, high-density fiberboard (HDF) panels from hardwood fibers bonded with urea-formaldehyde (UF) resin and a novel ammonium lignosulfonate (ALS) is investigated in this paper. HDF panels were fabricated in the laboratory by applying a very low UF gluing factor (3%) and ALS content varying from 6% to 10% (based on the dry fibers). The physical and mechanical properties of the fiberboards, such as water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE), bending strength (MOR), internal bond strength (IB), as well as formaldehyde content, were determined in accordance with the corresponding European standards. Overall, the HDF panels exhibited very satisfactory physical and mechanical properties, fully complying with the standard requirements of HDF for use in load-bearing applications in humid conditions. Markedly, the formaldehyde content of the laboratory fabricated panels was extremely low, ranging between 0.7–1.0 mg/100 g, which is, in fact, equivalent to the formaldehyde release of natural wood.

scholarly journals Effect of Photoinitiator on Precursory Stability and Curing Depth of Thiol-Ene Clickable Gelatin

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1877
Author(s):  
Kai-Hung Yang ◽  
Gabriella Lindberg ◽  
Bram Soliman ◽  
Khoon Lim ◽  
Tim Woodfield ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Visible Light ◽  
Rheological Properties ◽  
Swelling Ratio ◽  
Sodium Persulfate ◽  
Photo Polymerization ◽  
Gelation Kinetics ◽  
The Stability ◽  
Over Time

Recent advances highlight the potential of photopolymerizable allylated gelatin (GelAGE) as a versatile hydrogel with highly tailorable properties. It is, however, unknown how different photoinitiating system affects the stability, gelation kinetics and curing depth of GelAGE. In this study, sol fraction, mass swelling ratio, mechanical properties, rheological properties, and curing depth were evaluated as a function of time with three photo-initiating systems: Irgacure 2959 (Ig2959; 320–500 nm), lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP; 320–500 nm), and ruthenium/sodium persulfate (Ru/SPS; 400–500 nm). Results demonstrated that GelAGE precursory solutions mixed with either Ig2959 or LAP remained stable over time while the Ru/SPS system enabled the onset of controllable redox polymerization without irradiation during pre-incubation. Photo-polymerization using the Ru/SPS system was significantly faster (<5 s) compared to both Ig2959 (70 s) and LAP (50 s). Plus, The Ru/SPS system was capable of polymerizing a thick construct (8.88 ± 0.94 mm), while Ig2959 (1.62 ± 0.49 mm) initiated hydrogels displayed poor penetration depth with LAP (7.38 ± 2.13 mm) in between. These results thus support the use of the visible light based Ru/SPS photo-initiator for constructs requiring rapid gelation and a good curing depth while Ig2959 or LAP can be applied for photo-polymerization of GelAGE materials requiring long-term incubation prior to application if UV is not a concern.

scholarly journals KUALITAS PAPAN PARTIKEL BERDASARKAN KOMPOSISI SEKAM PADI DAN KAYU SENGON DENGAN VARIASI KADAR PEREKAT

2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Dendi Prayoga ◽  
. Dirhamsyah ◽  
. Nurhaida
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Rice Husk ◽  
Raw Materials ◽  
Urea Formaldehyde ◽  
Physical And Mechanical Properties ◽  
Solid Content ◽  
Particle Board ◽  
Rice Husks ◽  
Wood Processing

This research aimed to examine the physical and mechanical properties of particle boards based on the composition of raw materials and adhesive content and know the treatment of the composition of raw materials and the best adhesive content and meet the standard JIS A 5908-2003. The research was conducted at Wood Workshop Laboratory, Wood Processing Laboratory Faculty of Forestry,Tanjungpura University and Laboratory of PT. Duta Pertiwi Nusantara Pontianak. The adhesive used is Urea Formaldehyde with 52% Solid Content. Comparison of the composition of rice husks and sengon varies namely rice husk 50%: sengon 50%, rice husk 60%: sengon 40% and rice husk 70%: sengon 30%  and variations in the levels of UF adhesives, namely 14% and 16%, with target density 0,7 gr/cm3. The particleboard was 30 cm x 30 cm x 1 cm Pressing at temperature 140oC for 8 minutes, with  pressure of 25 kg/cm2. The research results of the study of density and moisture content meet the standards JIS A 5908-2003. The best particle values of rice husk and sengon  with composition a ratio of  rice husk 50%: sengon 50% , 16% adhesive content  16%, with density value of  0,7072 gr/cm3, moisture content 9,1949 %, thick development 12,3210 %, water absorption 68,8270 %, MOE 12110,7273 kg/cm2, MOR 161,0025 kg/cm2, firmness sticky 1,9320 kg/cm2, screw holding strength 62,3124 kg.Keywords : adhesive, composition, particle board, rice husk, sengon

scholarly journals New crosslinkers for electrospun chitosan fibre mats. I. Chemical analysis

2012 ◽  
Vol 9 (75) ◽  
pp. 2551-2562 ◽  
Author(s):  
Marjorie S. Austero ◽  
Amalie E. Donius ◽  
Ulrike G. K. Wegst ◽  
Caroline L. Schauer
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Mechanical Stability ◽  
Dissolution Tests ◽  
Natural Polysaccharide ◽  
Biomedical Field ◽  
The Stability ◽  
Scanning Electron

Chitosan (CS), the deacetylated form of chitin, the second most abundant, natural polysaccharide, is attractive for applications in the biomedical field because of its biocompatibility and resorption rates, which are higher than chitin. Crosslinking improves chemical and mechanical stability of CS. Here, we report the successful utilization of a new set of crosslinkers for electrospun CS. Genipin, hexamethylene-1,6-diaminocarboxysulphonate (HDACS) and epichlorohydrin (ECH) have not been previously explored for crosslinking of electrospun CS. In this first part of a two-part publication, we report the morphology, determined by field emission scanning electron microscopy (FESEM), and chemical interactions, determined by Fourier transform infrared microscopy, respectively. FESEM revealed that CS could successfully be electrospun from trifluoroacetic acid with genipin, HDACS and ECH added to the solution. Diameters were 267 ± 199 nm, 644 ± 359 nm and 896 ± 435 nm for CS–genipin, CS–HDACS and CS–ECH, respectively. Short- (15 min) and long-term (72 h) dissolution tests (T 600 ) were performed in acidic, neutral and basic pHs (3, 7 and 12). Post-spinning activation by heat and base to enhance crosslinking of CS–HDACS and CS–ECH decreased the fibre diameters and improved the stability. In the second part of this publication, we report the mechanical properties of the fibres.

Determination of native (wood derived) formaldehyde by the desiccator method in particleboards generated during panel production

Holzforschung ◽  
2010 ◽  
Vol 64 (4) ◽  
Author(s):  
Michael J. Birkeland ◽  
Linda Lorenz ◽  
James M. Wescott ◽  
Charles R. Frihart
Keyword(s):  
Hot Pressing ◽  
Urea Formaldehyde ◽  
Chromotropic Acid ◽  
Monitoring Methods ◽  
Emission Testing ◽  
Short And Long Term ◽  
The Common ◽  
Short Time

Abstract Hot-pressing wood, particularly in the production of wood composites, generates significant “native” (wood-based) formaldehyde (FA), even in the absence of adhesive. The level of native FA relates directly to the time and temperature of hot-pressing. This native FA dissipates in a relatively short time and is not part of the long-term FA emission issue commonly associated with hydrolyzing urea-formaldehyde bonds. This paper demonstrates that the common desiccator/chromotropic acid method is very specific for FA and is not influenced by other volatile compounds set free from wood during hot-pressing. Furthermore, it is shown that particleboard produces native FA at high levels even in the absence of adhesives or in the presence of one type of no-added formaldehyde (NAF) adhesive. Soy-based adhesives suppress native FA emission and provide low FA emission levels in both the short and long term. This study highlights an often overlooked aspect that should be considered for emission testing: standardizing the time and conditions employed immediately after pressing and prior to the onset of emissions testing. Addressing this issue in more detail would improve the reliability of correlation between data obtained by rapid process monitoring methods and emission measurements in large chambers.

Mechanical Properties of Fir Sawdust Composite Modified by Basalt Glass Powder

2012 ◽  
Vol 627 ◽  
pp. 734-736
Author(s):  
Kai Fang Xie ◽  
Hua Wu Liu ◽  
Wei Wei Hu ◽  
Han Sun ◽  
Shu Wei Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Fire Resistance ◽  
Glass Powder ◽  
Bending Strength ◽  
Moisture Sorption ◽  
Weight Fraction ◽  
Basalt Glass ◽  
Temperature Conditions ◽  
The Stability

Fir sawdust panel was modified by basalt glass powder, in order to improve the stability during moisture sorption, durability under frequently wear, and fire resistance for working in high temperature conditions. The strengths of the modified panels were evaluated in this study. The maximum tensile 21.964MPa was reached when the weight fraction of basalt glass power was 15%, which was 86.58% stronger than the panel without basalt glass powder. When the content of basalt glass powder was 10%, the bending strength of the fir sawdust panel reached the maximum 37.9MPa, and was improved by 38.21%. However, the influence of the reinforcement to the elongation was negligible.

scholarly journals Influence of Air Plasma Pretreatments on Mechanical Properties in Metal-Reinforced Laminated Wood

2022 ◽  
Vol 8 ◽  
Author(s):  
Sebastian Dahle ◽  
Kavyashree Srinivasa ◽  
Jure Žigon ◽  
Arnaud Maxime Cheumani Yona ◽  
Georg Avramidis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Mechanical Performance ◽  
Mechanical Load ◽  
Urea Formaldehyde ◽  
Air Plasma ◽  
Adhesive Systems ◽  
Plasma Treatments ◽  
Structural Applications ◽  
The Impact

The use of wood-based materials in building and construction is constantly increasing as environmental aspects and sustainability gain importance. For structural applications, however, there are many examples where hybrid material systems are needed to fulfil the specific mechanical requirements of the individual application. In particular, metal reinforcements are a common solution to enhance the mechanical properties of a wooden structural element. Metal-reinforced wood components further help to reduce cross-sectional sizes of load-bearing structures, improve the attachment of masonry or other materials, enhance the seismic safety and tremor dissipation capacity, as well as the durability of the structural elements in highly humid environments and under high permanent mechanical load. A critical factor to achieve these benefits, however, is the mechanical joint between the different material classes, namely the wood and metal parts. Currently, this joint is formed using epoxy or polyurethane (PU) adhesives, the former yielding highest mechanical strengths, whereas the latter presents a compromise between mechanical and economical constraints. Regarding sustainability and economic viability, the utilization of different adhesive systems would be preferable, whereas mechanical stabilities yielded for metal-wood joints do not permit for the use of other common adhesive systems in such structural applications. This study extends previous research on the use of non-thermal air plasma pretreatments for the formation of wood-metal joints. The plasma treatments of Norway spruce [Picea abies (L.) Karst.] wood and anodized (E6/EV1) aluminum AlMgSi0.5 (6060) F22 were optimized, using water contact angle measurements to determine the effect and homogeneity of plasma treatments. The adhesive bond strengths of plasma-pretreated and untreated specimens were tested with commercial 2-component epoxy, PU, melamine-urea formaldehyde (MUF), polyvinyl acetate (PVAc), and construction adhesive glue systems. The influence of plasma treatments on the mechanical performance of the compounds was evaluated for one selected glue system via bending strength tests. The impact of the hybrid interface between metal and wood was isolated for the tests by using five-layer laminates from three wood lamellae enclosing two aluminum plates, thereby excluding the influence of congeneric wood-wood bonds. The effect of the plasma treatments is discussed based on the chemical and physical modifications of the substrates and the respective interaction mechanisms with the glue systems.

STUDY OF THE INFLUENCE OF STABILIZERS ON THE PROPERTIES OF CARBAMIDE FOR-MALDEHYDE BINDER AND FC PLYWOOD

2020 ◽  
Vol 10 (1) ◽  
pp. 136-143
Author(s):  
A. Fedotov ◽  
Tat'yana Vahnina ◽  
Andrey Titunin ◽  
Aleksandr Sviridov
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Urea Formaldehyde ◽  
Physical And Mechanical Properties ◽  
Strength Reduction ◽  
Cohesive Strength ◽  
Urea Formaldehyde Resin ◽  
Strength Characteristics ◽  
Formaldehyde Resin ◽  
Glycerol Mono

The problem of stabilizing the properties of the urea-formaldehyde binder during storage is relevant for both glued products and resins. Changing the performance of the resin during storage makes it difficult to apply a binder and leads to a deterioration in the physical and mechanical properties of plywood. The effect of glycerol, mono- and triethanolamine, as well as a mixture of glycerol and monoethanolamine on the nominal viscosity of the resin after 56 days of storage, has been studied. The use of glycerol and monoethanolamine (including in the complex) reduces the nominal viscosity of the resin by 13.5-24.8%. The use of triethanolamine as a stabilizer makes it possible to reduce the nominal viscosity by 35% in comparison with the index of an unstabilized oligomer. Mechanical properties of FC plywood based on the stabilized and unstabilized binder has been studied. It was found that glycerol additive (or glycerol in combination with monoethanolamine) significantly reduces strength characteristics of plywood, which makes it irrational to use these stabilizers. The addition of 0.2% triethanolamine to CFS allows a 35% reduction in the nominal viscosity of the resin, while the cohesive strength of the binder decreases by 1.5%. The result is within the framework of the dispersion of the indicator, i.e. strength reduction is negligible. The static bending strength of plywood with a stabilized triethanolamine binder is more important than that of control specimens without the addition of stabilizers. The results of the study enable to recommend the addition of triethanolamine in an amount of 0.2% by weight of urea-formaldehyde resin as a rational stabilizer

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