The Effect of Veneer Densification Temperature and Wood Species on the Plywood Properties Made from Alternate Layers of Densified and Non-Densified Veneers

In this study the properties of plywood manufactured from densified and non-densified veneer sheets and alternate layers of such veneers with and without densification using low amount of adhesive as a function of densification temperature and wood species were investigated. The plywood panels were made from rotary-cut birch and black alder veneers using urea-formaldehyde (UF) adhesive. Veneer sheets with thickness of 1.5 mm were subjected to the thermal-compression at three different temperatures while keeping constant the pressure during a same time span. Five-layers plywood panels were produced using a constant hot-pressing schedule using different amounts of glue spread as a function of the plywood type; such as plywood made from non-densified (80 g/m2) and densified (60 g/m2) veneers only; and combination of them (70 g/m2). The bending strength (MOR) and the modulus of elasticity (MOE) along with the shear strength of the plywood samples for bonding class 1 (dry conditions) have been determined. As expected bending strength of the plywood samples increased with the increasing in density. The increase of veneer densification temperature resulted in a gradually decrease of MOR; MOE and shear strength values for the plywood panels made of densified veneers and mixed panels of both species. The temperature of 150 °C for veneer densification seemed to be enough to achieve enhanced bending and bonding properties. All plywood panels in this study were manufactured using reduced glue consumption and they presented satisfactory properties performance for indoor applications.

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

Polymers ◽

10.3390/polym12112582 ◽

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.

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Utilization of Partially Liquefied Bark for Production of Particleboards

Applied Sciences ◽

10.3390/app10155253 ◽

2020 ◽

Vol 10 (15) ◽

pp. 5253 ◽

Cited By ~ 1

Author(s):

Wen Jiang ◽

Stergios Adamopoulos ◽

Reza Hosseinpourpia ◽

Jure Žigon ◽

Marko Petrič ◽

...

Keyword(s):

Bending Strength ◽

Urea Formaldehyde ◽

Value Added ◽

Thickness Swelling ◽

Mechanical And Physical Properties ◽

Dry Conditions ◽

Synthetic Adhesives ◽

European Standards ◽

Muf Adhesives

Bark as a sawmilling residue can be used for producing value-added chemicals and materials. This study investigated the use of partially liquefied bark (PLB) for producing particleboard with or without synthetic adhesives. Maritime pine (Pinus pinaster Ait.) bark was partially liquefied in the presence of ethylene glycol and sulfuric acid. Four types of particleboard panels were prepared with a PLB content of 4.7%, 9.1%, 20%, and 33.3%, respectively. Another five types of particleboard panels were manufactured by using similar amounts of PLB and 10 wt.% of melamine–urea–formaldehyde (MUF) adhesives. Characterization of bark and solid residues of PLB was performed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and automated vapor sorption (AVS). Mechanical and physical properties of the particleboard were tested according to the European standards EN 310 for determining modulus of elasticity and bending strength, EN 317 for determining thickness swelling after immersion in water, and EN 319 for determining internal bond strength. The results showed that the increase in PLB content improved the mechanical strength for the non-MUF boards, and the MUF-bonded boards with up to 20% of PLB met the requirements for interior uses in dry conditions according to EN 312. The non-MUF boards containing 33.3% of PLB and the MUF-bonded boards showed comparable thickness swelling and water absorption levels compared to the reference board.

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Feasibility of using waste sweet bay wood (Laurus nobilis L.) in particleboard production

BioResources ◽

10.15376/biores.15.4.8175-8190 ◽

2020 ◽

Vol 15 (4) ◽

pp. 8175-8190

Author(s):

Hikmet Yazici

Keyword(s):

Bending Strength ◽

Urea Formaldehyde ◽

Middle Layer ◽

General Purpose ◽

Surface Layers ◽

Laurus Nobilis ◽

Leaf Processing ◽

Processing Plants ◽

Dry Conditions ◽

Group A

Turkey holds a 95% market share of global sweet bay (Laurus nobilis L.) leaf trade, and it has 25 leaf processing and manufacturing facilities with different capacities. In this study, the usability of waste sweet bay wood (BW) that was removed from bay leaf processing plants was studied. For this purpose, three-layer particleboards were produced by mixing industrial chips (IC) and waste sweet bay wood chips (BWC) at a mixture rate of 0%, 25%, 50%, 75%, and 100%. For panel production, urea formaldehyde adhesive (UF) was used in 10% of the surface layers and in 8% of the middle layer based on dry chip weight. Some mechanical properties, such as bending strength (BS), modulus of elasticity in bending (MOE), internal bond strength (IB) of the test panels, thickness swelling (TS), and water absorption (WA) amounts, were determined. The results showed that all panel groups except group C (25% BWC + 75% IC) met the general purpose panel class (P1) requirements for use in dry conditions according to TS EN 312 (2012). In addition, group A panels (100% BWC) met the requirements of P2 class for the MOE and BS, and group E panels (75% BWC + 25% IC) met the P3 standards. The results showed that BWC could be used to produce particleboard for general purposes, including furniture.

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Effects of the thickness of rotary-cut veneers on properties of plywood sheets. Part 2. Physical and mechanical properties of plywood materials

Journal of Forest Science ◽

10.17221/4493-jfs ◽

2012 ◽

Vol 52 (No. 3) ◽

pp. 118-129

Author(s):

J. Hrázský ◽

P. Král

Keyword(s):

Mechanical Properties ◽

Shear Strength ◽

Bending Strength ◽

Urea Formaldehyde ◽

Physical And Mechanical Properties ◽

Urea Formaldehyde Resin ◽

Formaldehyde Resin ◽

Institutional Research ◽

Nominal Thickness

The second part of the paper summarizes results of an institutional research aimed at the determination of physical and mechanical properties of different sets of plywood sheets pressed under different conditions. The first part dealt with the determination of compressibility or values of decreasing the thickness of pressed plywood sheets. In this second part, results are summarized of the analysis of physical and mechanical properties of the set of whole-beech plywood sheets of the nominal thickness of veneers amounting to 1.5 mm. The plywood sheets were manufactured as seven-ply and urea-formaldehyde resin DUKOL S was used for their production. The sheets were pressed using a pressure of 1.5 and 1.7 MPa. Following parameters were analyzed: moisture, density, bending strength, MOE in bending and shear strength.

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Effects of moisture content on lap-shear, bending, and tensile strength of lap-jointed and finger-jointed southern pine using phenol resorcinol formaldehyde and melamine urea formaldehyde

BioResources ◽

10.15376/biores.15.2.3534-3544 ◽

2020 ◽

Vol 15 (2) ◽

pp. 3534-3544 ◽

Cited By ~ 2

Author(s):

Jian Liu ◽

Kong Yue ◽

Feng Wang ◽

Jinhao Wu ◽

Zhongqiu Tang ◽

...

Keyword(s):

Tensile Strength ◽

Shear Strength ◽

Bending Strength ◽

Urea Formaldehyde ◽

Southern Pine ◽

Resorcinol Formaldehyde ◽

Bonding Performance ◽

Lap Shear ◽

Bonding Shear Strength ◽

Shear Bending

The bonding performance of the phenol-resorcinol-formaldehyde adhesive (PRF) and melamine-urea-formaldehyde adhesive (MUF) with southern pine as substrates at various moisture contents (MC) was evaluated. The results showed that bonding shear strength with MUF and PRF was negatively related to wood MC, and bonding shear strength with MUF was higher than that of the PRF. The bending and tensile strengths of finger-jointed lumber decreased with wood MC. The bending strength of finger-jointed lumber was affected more by wood than adhesive. However, both wood and adhesive exhibited the same important contribution to the tensile strength.

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Effect of Different Hardwood Species and Lay-Up Schemes on the Mechanical Properties of Plywood

Forests ◽

10.3390/f11060649 ◽

2020 ◽

Vol 11 (6) ◽

pp. 649 ◽

Cited By ~ 1

Author(s):

Heikko Kallakas ◽

Anti Rohumaa ◽

Harti Vahermets ◽

Jaan Kers

Keyword(s):

Mechanical Properties ◽

Wood Species ◽

Bending Strength ◽

Processing Parameters ◽

Strength Properties ◽

Product Density ◽

Black Alder ◽

Hardwood Species ◽

Birch Veneer

In Estonia, hardwoods form approximately 50% of all forest area, where the main species are birch (30%), gray alder (9%), aspen (6%) and black alder (4%). Birch has been extensively used by the veneer-based industry, but species like black alder, gray alder and aspen have not been commonly used by the veneer-based products industry due to the lower quality of this resource. The aim of this research is to determine the effect of different lay-up schemes and usages of gray alder, black alder and aspen on the mechanical properties of plywood, by replacing birch veneer in the plywood core with alternative wood species. The main veneer and plywood characteristics will be evaluated according to the current standards, e.g., veneer strength perpendicular to grain, plywood bonding and bending strength, and modulus of elasticity. All processing parameters will be kept similar to those used generally by birch plywood manufacturers. The results showed that birch and black alder plywood panels had generally the highest bending strength properties, followed by grey alder and aspen. It was also found that, for proper gluing, birch veneers had the lowest glue consumption, 152 g/m2, and aspen had the highest glue consumption, 179 g/m2. It was found that when lower density wood was used in the plywood, the product density increased. Low density wood veneers had higher glue consumption, and also higher compaction in thickness than birch veneers under the same pressure. Overall, it was shown that the wood species used in this study have slightly lower strength properties, but with proper lay-up schemes, these wood species could be successfully used by the veneer-based products industry.

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Influence of anatomy on the adhesion performance of four wood species

Research Society and Development ◽

10.33448/rsd-v9i4.2727 ◽

2020 ◽

Vol 9 (4) ◽

pp. e31942727

Author(s):

João Gabriel Missia da Silva ◽

Pedro Nicó de Medeiros ◽

Denise Ransolin Soranso ◽

Vinicius Peixoto Tinti ◽

José Tarcísio da Silva Oliveira ◽

...

Keyword(s):

Shear Strength ◽

Specific Gravity ◽

Wood Species ◽

Tectona Grandis ◽

Glue Line ◽

Anatomical Characteristics ◽

Ray Cells ◽

Adhesion Performance ◽

Adhesion Process

The aim of this study was to evaluate the influence of anatomical characteristics on the adhesion performance of Vatairea sp., Paulownia sp., Aspidosperma populifolium and Tectona grandis wood. Specimens for anatomical, physical and mechanical analyzes were produced from tangentially oriented boards. The treatments were joint glued from pieces of the same anatomical orientation (radial and tangential), evaluated for shear strength and glue line failure. The Vatairea sp wood had the highest specific gravity (0.74 g cm-3) and the Paulownia sp (0.34 g cm-3) wood was smaller. Aspidosperma populifolium species showed the highest shear strength in the glue line in the tangential and radial faces. The anatomical variables with higher influence on the wood adhesion process were pith ray cells and especially fibers that exhibit the greatest correlation with the shear strength of the glue line.

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Potential of Brewer’s Spent Grain as a Potential Replacement of Wood in pMDI, UF or MUF Bonded Particleboard

Polymers ◽

10.3390/polym13030319 ◽

2021 ◽

Vol 13 (3) ◽

pp. 319

Author(s):

Marius Cătălin Barbu ◽

Zeno Montecuccoli ◽

Jakob Förg ◽

Ulrike Barbeck ◽

Petr Klímek ◽

...

Keyword(s):

Internal Bond ◽

Mechanical Performance ◽

Animal Feed ◽

Urea Formaldehyde ◽

Modulus Of Rupture ◽

Brewer’S Spent Grain ◽

Beer Brewing ◽

Removal Of Heavy Metals ◽

Dry Conditions ◽

Spent Grain

Brewer’s spent grain (BSG) is the richest by-product (85%) of the beer-brewing industry, that can be upcycled in a plentiful of applications, from animal feed, bioethanol production or for removal of heavy metals from wastewater. The aim of this research is to investigate the mechanical, physical and structural properties of particleboard manufactured with a mixture of wood particles and BSG gradually added/replacement in 10%, 30% and 50%, glued with polymeric diisocyanate (pMDI), urea-formaldehyde (UF) and melamine urea-formaldehyde (MUF) adhesives. The density, internal bond, modulus of rupture, modulus of elasticity, screw withdrawal resistance, thickness swelling and water absorption were tested. Furthermore, scanning electron microscopy anaylsis was carried out to analyze the structure of the panels after the internal bond test. Overall, it was shown that the adding of BSG decreases the mechanical performance of particleboard, due to reduction of the bonding between wood and BSG particles. This decrease has been associated with the structural differences proven by SEM inspection. Interaction of particles with the adhesive is different for boards containing BSG compared to those made from wood. Nevertheless, decrease in the mechanical properties was not critical for particleboards produced with 10% BSG which could be potentially classified as a P2 type, this means application in non-load-bearing panel for interior use in dry conditions, with high dimensional stability and stiffness.

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

Polymers ◽

10.3390/polym13040511 ◽

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.

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

Polymers ◽

10.3390/polym13020220 ◽

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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