scholarly journals Effect of Veneer-Drying Temperature on Selected Properties and Formaldehyde Emission of Birch Plywood

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 593 ◽  
Author(s):  
Pavlo Bekhta ◽  
Ján Sedliačik ◽  
Nataliya Bekhta
Keyword(s):  
Modulus Of Elasticity ◽  
Bonding Strength ◽  
Elevated Temperatures ◽  
Bending Strength ◽  
Phenol Formaldehyde ◽  
Urea Formaldehyde ◽  
Physical And Mechanical Properties ◽  
Formaldehyde Emission ◽  
Bonding Quality ◽  
Mean Values

In this study, the effect of the veneer-drying process at elevated temperatures on selected properties and formaldehyde emission of plywood panels was determined. We assume that during the veneer drying at high temperatures, more formaldehyde is released from it, and therefore, a lower formaldehyde emission can be expected from the finished plywood. Prior to bonding, birch veneers were dried at 160 °C (control) and 185 °C in an industrial veneer steam dryer (SD) and at 180 °C, 240 °C and 280 °C in an industrial veneer gas dryer (GD). Two types of adhesives were used: urea–formaldehyde (UF) and phenol–formaldehyde (PF) resins. Bonding quality, bending strength and modulus of elasticity in bending, water absorption and thickness swelling of plywood samples were determined. The formaldehyde emission level of samples was also measured. It was concluded from the study that the effects of veneer-drying temperatures on the bonding strength and physical and mechanical properties of plywood panels were significant. Veneer-drying temperatures of 185 °C/SD, 180 °C/GD and 240 °C/GD negatively affected the bending strength and the modulus of elasticity along and across the fibres for both UF and PF plywood samples. Bonding strength mean values obtained from all test panels were above the required value (1.0 MPa) indicated in EN 314-2 standard. The lowest formaldehyde emissions for the UF and PF plywood samples were observed in the samples from veneer dried in a steam dryer at 185 °C/SD.

scholarly journals USE OF ARTIFICIAL NEURAL NETWORKS IN PREDICTING PARTICLEBOARD QUALITY PARAMETERS

2016 ◽  
Vol 40 (5) ◽  
pp. 949-958 ◽  
Author(s):  
Rafael Rodolfo de Melo ◽  
Eder Pereira Miguel
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Bending Strength ◽  
Phenol Formaldehyde ◽  
Urea Formaldehyde ◽  
Eucalyptus Grandis ◽  
Physical And Mechanical Properties ◽  
Quality Parameters ◽  
Physical Density ◽  
Artificial Neural

ABSTRACT This study aims to assess Artificial Neural Networks (ANN) in predicting particleboard quality based on its physical and mechanical properties. Particleboards were manufactured using eucalyptus (Eucalyptus grandis) and bonded with urea-formaldehyde and phenol-formaldehyde resins. To characterize quality, physical (density and water absorption and thickness swelling after 24-hour immersion) and mechanical (static bending strength and internal bond) properties were assessed. For predictions, adhesive type and particleboard density were adopted as ANN input variables. Networks of multilayer Perceptron (MLP) were adopted, training 100 networks for each assessed parameter. The results pointed out ANN as effective in predicting quality parameters of particleboards. With this technique, all the assessed properties presented models with adjustments higher than 0.90.

scholarly journals Properties of Plywood Produced with Urea-Formaldehyde Adhesive Modified with Nanocellulose and Microcellulose

2020 ◽  
Vol 71 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Jakub Kawalerczyk ◽  
Dorota Dziurka ◽  
Radosław Mirski ◽  
Kinga Szentner
Keyword(s):  
Mechanical Properties ◽  
Modulus Of Elasticity ◽  
Urea Formaldehyde ◽  
Rheological Behaviour ◽  
Formaldehyde Emission ◽  
Solid Content ◽  
Curing Process ◽  
Gel Time ◽  
Bonding Quality ◽  
Adhesive Mixtures

Urea-formaldehyde adhesives are widely used in the wood-based materials industry. The study investigates the possibility of using cellulosic particles as a filler that modifies the properties of the resin and consequently improves the properties of plywood. Moreover, the study also examines the differences between microcellulose and nanocellulose used as a filler for UF adhesive. Based on the investigations, it was found that the addition of MFC and NCC significantly affected the curing process and rheological behaviour of adhesive mixtures. Modification led to increase of viscosity and extension of a gel time caused by lowering solid content of the resin. The experimental and reference plywood were tested in terms of bonding quality and mechanical properties such as modulus of elasticity and modulus of rigidity in accordance with applicable standards. The results of the tests confirmed that both the amount and the type of modifier added to the resin had a significant effect on the properties of plywood. The bonding quality and the above mentioned mechanical properties improved in all variants of modification; however the most effective was the addition of NCC in the amount of 10 %/100 g of solid resin. The slight decrease of formaldehyde emission was only observed for 5 % cellulosic particles added to 100 g of solid UF.

scholarly journals The effects of wood species, load direction, and adhesives on bending properties of laminated veneer lumber

BioResources ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. 3104-3112 ◽  
Author(s):  
Bekir Cihad Bal ◽  
İbrahim Bektaş
Keyword(s):  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Phenol Formaldehyde ◽  
Urea Formaldehyde ◽  
Eucalyptus Grandis ◽  
Variance Analysis ◽  
Modulus Of Rupture ◽  
Bending Properties ◽  
Laminated Veneer Lumber ◽  
Specific Modulus

In this study, the bending strength and stiffness of laminated veneer lumber (LVL) produced from beech (Fagus orientalis L.), poplar (Populus x euramericana I-214), and eucalyptus (Eucalyptus grandis W. Hill ex Maiden) wood using urea formaldehyde (UF), melamine urea formaldehyde (MUF), and phenol formaldehyde (PF) adhesives were determined. The tests were conducted in the flatwise and edgewise directions. The modulus of rupture (MOR), modulus of elasticity (MOE), specific modulus of rupture (SMOR), and specific modulus of elasticity (SMOE) were calculated. Variance analysis of the bending properties indicated that the effects of the species of tree, the direction of the load, and the type of adhesive were statistically significant. However, according to variance analysis of the SMOR, the effects of the type of adhesive were not significant. The results showed that the type of adhesive did not influence the bending properties of laminated veneer lumber. It can be stated that the differences among groups were due to differences in their densities. The direction of the load and the species of the tree had significant effects on the bending properties.

scholarly journals Furan resin as potential substitute for phenol-formaldehyde resin in plywood manufacturing

BioResources ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. 2727-2739
Author(s):  
Anca Maria Varodi ◽  
Emanuela Beldean ◽  
Maria Cristina Timar
Keyword(s):  
Mechanical Properties ◽  
Water Resistance ◽  
Bending Strength ◽  
Reference Product ◽  
Phenol Formaldehyde ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Furan Resin

Replacement of phenol-formaldehyde with a mixed furan resin is considered in this work as a means to improving plywood properties made with urea-formaldehyde-based adhesive currently made with an addition of phenol-formaldehyde resin. Previous research showed that the furan resins can improve water resistance and can provide long stability for the glue line. Plywood was manufactured with modified adhesives and characterized in comparison with a reference product. Thickness, physical properties (moisture content, density, and total water absorption), mechanical properties (shearing strength, bending strength, and elasticity modulus in bending), and formaldehyde emission were determined according to standardized methods. The results indicated that the addition of furan resin enhanced the water resistance by 43% and formaldehyde emission is according to E1 class. Also, the mechanical properties were improved; the shear strength for the adhesive composition with furan resin was increased by 14 to 30% compared with the reference product, depending on the testing conditions.

scholarly journals Possibility of Use of NCC-Reinforced Melamine-Urea- Formaldehyde Adhesive in Plywood Manufacturing

2021 ◽  
Vol 72 (3) ◽  
pp. 279-289
Author(s):  
Jakub Kawalerczyk ◽  
Dorota Dziurka ◽  
Radosław Mirski ◽  
Joanna Siuda ◽  
Marta Babicka
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Urea Formaldehyde ◽  
Fourier Transform Infrared ◽  
Bonding Quality ◽  
Adhesive Mixtures

The possibility of using nanocellulose (NCC) as a filling substance for melamine-urea-formaldehyde (MUF) adhesive was investigated for the process of manufacturing plywood. The adhesive mixtures were prepared with various nanocellulose concentrations. The amount of introduced filler had a significant effect on both resin and plywood characteristics. Fourier transform infrared spectroscopy (FTIR) did not show any major changes between experimental and reference variants. The viscosity of resin increased after the introduction of nanocellulose. The addition of NCC in the amount of 5 g and 10 g per 100 g of solid resin led to an improvement in bonding quality, modulus of elasticity and bending strength. Further increase of NCC concentration caused a deterioration of manufactured plywood properties. In summary, the addition of proper amount of nanocellulose resulted in manufacturing plywood with improved properties.

scholarly journals Straw based particleboard bonded with composite adhesives

BioResources ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 464-476
Author(s):  
Yanhua Zhang ◽  
Jiyou Gu ◽  
Haiyan Tan ◽  
Mingwei Di ◽  
Libin Zhu ◽  
...  
Keyword(s):  
Wheat Straw ◽  
Photoelectron Spectroscopy ◽  
Modulus Of Elasticity ◽  
Bonding Strength ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Modulus Of Rupture ◽  
Internal Bonding ◽  
Thickness Swelling ◽  
Internal Bonding Strength

Environmentally friendly particleboard was prepared with wheat straw, an inexpensive material. The particleboard was produced by a mixing process, using a composite adhesive comprised of urea-formaldehyde (UF) adhesives and EPU. The performance of the board was evaluated by measuring internal bonding strength (IB), thickness swelling, modulus of rupture (MOR), modulus of elasticity (MOE), and formaldehyde emission. The experimental results showed that maximum of dry and wet internal bonding strength, modulus of rupture, modulus of elasticity were 0.45MPa, 0.18MPa, 31.80MPa, and 5043MPa, respectively. The thickness swelling (TS2h) and thickness swelling (TS24h) were 3.9% and 10.7%, respectively. The composite adhesives and particleboards were measured by differential scanning calorimentry (DSC), dynamic mechanical analyzer (DMA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) measurements. The results indicated that the composite adhesive of UF/EPU could contribute to excellent mechanical, thermal, and water-resistant properties of the wheat straw particleboards.

scholarly journals Properties of Thermoplastic-Bonded Plywood: Effects of the Wood Species and Types of the Thermoplastic Films

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2582
Author(s):  
Pavlo Bekhta ◽  
Marcus Müller ◽  
Ilona Hunko
Keyword(s):  
Wood Species ◽  
Bonding Strength ◽  
Bending Strength ◽  
Low Cost ◽  
Urea Formaldehyde ◽  
Physical And Mechanical Properties ◽  
Environmentally Friendly ◽  
Significant Difference ◽  
Class 1 ◽  
Dry Conditions

There are a lack of proper adhesives that meet the wood industry requirements of being environmentally friendly, low cost, and easy to use; thus, the application of thermoplastic polymers, especially films, is promising. This work expands our knowledge about the possibility of using thermoplastic films for the production of environmentally friendly plywood. The effects of the adhesives type and wood species on the properties of plastic film bonded plywood were studied. Sliced veneers of two hardwoods (birch and beech) and one softwood (spruce) were used in the experiments. Three types of thermoplastic films—low-density polyethylene (LDPE), co-polyamide (CoPA), and co-polyester (CoPE)—were used as an adhesive for bonding plywood samples. Melamine–urea–formaldehyde (MUF) resin was used as a reference. The influence of the type of adhesive and wood species as well as their interaction on the properties of plywood was significant. The lowest bonding strength demonstrated plywood samples bonded by LDPE, and the highest bonding strength in the samples was shown in those bonded by CoPA. A significant difference was found between softwoods and hardwoods in terms of their influence on the physical and mechanical properties of plywood samples. From the obtained data, it follows that softwoods provide much lower values of bending strength (MOR), modulus of elasticity (MOE), and bonding strength than hardwoods. The obtained bonding strength values of plastic-bonded plywood panels ranged from 1.18 to 2.51 MPa and met the European standard EN 314-2 for Class 1 (dry conditions) plywood.

scholarly journals Thermal Degradation of Bonding Strength of Aspen Plywood

2020 ◽  
Vol 71 (2) ◽  
pp. 185-192
Author(s):  
Pavlo Bekhta ◽  
Nataliya Bekhta
Keyword(s):  
Exposure Time ◽  
Bonding Strength ◽  
Elevated Temperatures ◽  
Phenol Formaldehyde ◽  
Mass Density ◽  
Urea Formaldehyde ◽  
Statistical Regression ◽  
Colour Difference ◽  
Initial Strength ◽  
Shear Strength Test

The objective of this research was to study the effect of exposure time on the bonding strength of aspen plywood at elevated temperatures. The plywood samples were manufactured under laboratory conditions using two types of adhesive: urea-formaldehyde (UF) and phenol-formaldehyde (PF). The plywood samples were tested after exposure to three different temperatures (150 °C, 200 °C and 250 °C) and three exposure time levels (1, 2 and 3 hours) at each temperature. Additionally, a set of control samples was tested at room temperature. The quality of bonding was assessed by shear strength test in compliance with the requirements of the standard EN 314-1. The mass and density losses as well as colour changes of the plywood samples were also determined. The findings of this study indicated that exposure of plywood panels to elevated temperature caused significant degradation of their bonding strength. PF plywood samples lost 63.2 % of their initial strength after 3 h of exposure at 250 °C, while UF samples lost 65.9 % of their initial strength already after 3 h of exposure at the temperature of 200 °C. Statistical regression-based models were also developed for predicting the loss of plywood bonding strength as functions of mass and density losses and total colour difference. As the mass/density losses or total colour difference of panels increased, the losses in bonding strength increased too.

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.

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