Poplar Veneer Research Articles

Studies of Electroless Copper Plating on Poplar Veneer

Copper coating was deposited on poplar veneer using different relative concentrations of plating solution. The coating structure, thickness, crystal structure, surface resistivity, contact angle, surface free energy, and electromagnetic shielding effectiveness were investigated. The surface morphology and thickness were observed using scanning electron microscopy, and the crystal structure was analyzed using X-ray diffraction. Increasing the relative concentration of plating solution resulted in a uniform and dense coating structure, and the thickness notably increased. In addition, the lateral direction resistivity was two times greater than the longitudinal direction resistivity, and the surface wettability changed from hydrophilic to hydrophobic, which led to a decline in surface free energy. Electromagnetic shielding effectiveness reached 62 dB in the frequency range of 10 kHz to 1.5 GHz. The electroless plating copper veneer was optimal when the solution contained 80 g/L of CuSO4·5H2O, 20 g/L of C4O6H4KNa, 40 g/L of EDTA-2Na, and 40 mL/L of HCHO 40 mL/L.

Adhesive properties of water-washed cottonseed meal on four types of wood

The interest in natural product-based wood adhesives has been steadily increasing due to the environmental and sustainable concerns of petroleum-based adhesives. In this work, we reported our research on the utilization of water-washed cottonseed meal (WCM) as wood adhesives. The adhesive strength and water resistance of WCM adhesive preparations on poplar, Douglas fir, walnut, and white oak wood veneers were tested with press temperatures of 80, 100, and 130 °C. Our data indicated that raising the hot press temperature from 80 to 100–130 °C greatly increased the bonding strength and water resistance of the WCM adhesives. The general trend of the adhesive strength of WCM on the four wood species was Douglas fir > poplar ≈ white oak > walnut. The rough surface of Douglas fir with tipping features could enhance the mechanical interlocking between the wood fibers and adhesive slurry, contributing to the high adhesive strength. The dimensional swelling of the bonded wood pairs due to water soaking was in the order: thickness > width (i.e. perpendicular to the wood grain) > length (i.e. parallel to the wood grain). The greatest dimensional changes were observed in Douglas fir specimens. However, the highest decrease in adhesive strength by water soaking was with poplar wood specimens. These observations suggested that the wood dimensional changes were not dominant factors on water weakening the bonding strength of these wood pairs.

Improving the connection between wood and cement using LBL nanocoating to create a lightweight, eco-friendly structural material

Structural elements made out of cement bonded wood may be an excellent alternative to flammable organic bonded composite beams, and CO2 intensive, heavy and nonrenewable reinforced concrete. Unfortunately, preliminary studies showed that a sufficient load-bearing performance is difficult to achieve. Improving the compatibility of cement and wood by LbL nanocoating may be a significant step towards creating viable cement bonded wood load bearing elements.The study involved creating multi layer nanocoating on the surface of poplar veneer using various polyelectrolyte combinations and numbers of treatment cycles, and testing the withdrawal resistance of the samples from a cement matrix. PDDA-PSS treatment was found to form increasingly uniform coating on the surface of wood, while the results were less straightforward for PAH-PSS. Both types and all levels of treatment caused dramatic improvement in load withdrawal resistance. The best result - a more than tenfold improvement - was achieved by at least 10 cycles of PDDA-PSS treatment. PAH-PSS treatment yielded a somewhat more modest improvement, which was already evident after five treatment cycles. The results point to the excellent potential of LbL nanocoating for creating cement bonded structural wood based composite materials.

The effect of span-to-depth ratio on the impact bending strength of poplar LVL

In this study, it was studied the effect of span-to-depth ratio on the impact bending strength of laminated veneer lumber (LVL). For the study, LVL boards were produced from rotary-cut poplar veneer using phenol formaldehyde (PF) adhesive. Test samples were prepared from the boards to determine impact bending strength, density, moisture content, and tensile-shear strength. In addition, the compression ratio and densification ratios of LVL for each panel was determined. The impact bending strengths were tested in flatwise and edgewise directions for different span-to-depth ratios, i.e., 7.5, 10, 12.5, 15, 17.5, and 20. The highest impact bending strength was measured when the span-to-depth ratio was 20. The lowest impact bending strength was measured when the span-to-depth ratio was 10. There was a parabolic relationship between impact bending strength and the span-to-depth ratio. In addition, the test results showed that the impact bending strength of all of the samples tested in the flatwise direction were significantly higher than those tested in the edgewise direction.

Effect of Plasma Processing Rate on Poplar Veneer Surface and its Application in Plywood

Dielectric barrier discharge (DBD) plasma at atmospheric pressure in air was applied to a poplar veneer surface. Effects of plasma processing rate on surface morphology, chemical property, and surface wettability of the poplar veneer were investigated. The adhesion strength of urea formaldehyde (UF) glued plywood manufactured from the modified veneer was also studied. Atomic force microscopy (AFM), electron spin-resonance spectroscopy (ESR), X-ray photoelectron spectroscopy (XPS), contact angle tests, and shear strength tests were carried out. AFM indicated that the surface roughness increased after plasma treatment and was the maximum at a processing rate of 14 m/min. Both ESR and XPS tests showed more oxygen accumulation on the wood surface, forming various oxygen-containing chemical groups. Contact angle tests showed better wetting at a decreased plasma processing rate. Consequently, the adhesion strength of plywood increased after plasma treatment and showed higher strength at lower processing rates.

Development of an industrial applicable dielectric barrier discharge (DBD) plasma treatment for improving bondability of poplar veneer

Abstract Dielectric barrier discharge (DBD) plasma treatment in a larger scale, which has the potential for industrial application, was studied for modification of poplar veneer surface for enhancing its interface adhesion. Chemical property, morphology, surface wetting, adhesion property and the stability of the activation after plasma treatment were investigated. ESR, XPS, AFM, contact angle (CA), and shear strength test were carried out to evaluate the effect of plasma treatment. The following properties increased after treatment: the surface free radical concentration, O/C ratio, surface roughness of wood fiber, veneer surface wetting, and surface free energy. Consequently, the plywood composite prepared after plasma treatment showed higher adhesion strength than that prepared from untreated veneer. The best plywoods were obtained from veneers treated at processing power of 4.5 kW of DBD. The time-dependent analysis by surface wetting indicated a modified stability in the first two days after plasma treatment, after which the polar component of the surface decreased and its dispersive component kept the level observed after plasma treatment. In summary, veneer surface modification by DBD plasma is promising for industrial application.

The Preparation, Characterization, and Influence of Multiple Electroless Nickel-Phosphorus (Ni-P) Composite Coatings on Poplar Veneer

Nickel-Phosphorus (Ni-P) composite coatings were prepared on a poplar veneer surface via a simple electroless nickel (Ni) approach. The substrate deformation, flatness, crystalline structure, and wear resistance of the Ni-P composite coatings were investigated. The deformation degree of the substrate decreased as the number of deposition steps was increased. The flatness and wear resistance of the composite coatings were enhanced with the increase in the number of depositions. The full width, at half of the maximum values of Ni X-ray diffraction (XRD), of peaks in the composite coatings were broadened and strengthened with an increment of the number of depositions in the coatings. The XRD patterns revealed that the Ni that had been deposited on poplar veneer had a crystallite size structure between 42 and 88 A. The composite structure was characterized with scanning electron microscopy (SEM) images. The uniformity of the particles in the composite coatings could be improved with the increase in the number of depositions. The wear resistance of ideal coatings with a homogeneous thickness was measured via the rolling wear testing machine (RWTM), and the wear resistance of the coatings was increased by 200% compared with that of coatings obtained via a single deposition.

Some technological properties of poplar plywood panels reinforced with glass fiber fabric

The reinforcement of solid wood and wood-based composite materials is not a new idea, but there have been very few studies about reinforcing poplar plywood with glass fiber fabric using phenol formaldehyde. In this study, plywood panels were produced using poplar veneer and phenol formaldehyde adhesive and glass fiber fabric. One control group and three different test groups were set up. In addition, perpendicular and parallel test samples for each group were set up for bending tests. Some of the physical and mechanical properties of the reinforced plywood were determined using various tests. The results of the testing indicated that the plywood that was reinforced with woven glass fiber had a significantly increased modulus of rapture and modulus of elasticity of perpendicular samples. It was determined that density of the plywood was increased in the test groups. Thickness swelling and water absorption decreased for the test groups in which the plywood samples had woven glass fibers bonded onto in their surfaces. In the bending tests, the reinforcement provided by the glass fiber fabric decreased the inequalities between the parallel and perpendicular samples.

Evaluation of Canadian Prairie-Grown Hybrid Poplar for High Value Solid Wood Products

Studies were carried out to evaluate the suitability of Canadian prairie-grown, short-rotation hybrid poplar for the manufacture of high value solid wood products, including appearance grade lumber, plywood, laminated veneer lumber (LVL) and oriented strandboard (OSB). For appearance grade lumber applications, hybrid poplar was found to be an attractive wood as it machined and finished well. This wood can be finished to take on a number of different looks or to resemble other species. Hybrid poplar would appear suitable in applications such as millwork, mouldings, turnings and bedroom furniture where other softer hardwood species such as red alder (Alnus rubra Bong.) and yellow poplar (Liriodendron tulipifera L.) are currently being used. Hybrid poplar veneer was suitable for manufacturing high quality plywood, either used by itself, or mixed with other species such as aspen (Populus tremuloides Mich.) or spruce (Picea spp.). If the hybrid poplar veneer is stress graded, a portion of the veneer would be suitable for manufacturing structural grade LVL. Hybrid poplar can be processed commercially using procedures similar to those used for manufacturing aspen plywood and LVL. Properties of OSB manufactured from hybrid poplar were fully equivalent to those of OSB manufactured from aspen. Hybrid poplar can be substituted for aspen in OSB at any level with no apparent effect on panel properties.

Surface Characterization of Plasma-modified Poplar Veneer: Dynamic Wettability

The dynamic wettability of plasma-modified poplar veneer was investigated with sessile adhesive droplets using a wetting model. Dynamic contact angle, instantaneous and equilibrium contact angles, and their rates of change (K-value) were used to illustrate the dynamic wetting process. The experiment consisted of selecting treatment parameters (type of gas, power) that would lead to the increased wettability of wood. Three resin systems, urea-formaldehyde (UF), phenol-formaldehyde (PF), and diphenylmethylene diisocyanate (MDI), were evaluated. Based on the wetting model, the K-value was used to interpret the kinetics of wetting. The higher the K-value, the faster the contact angle reaches equilibrium, and the faster the liquid penetrates and spreads. Therefore, the model was helpful for characterizing the dynamic wettability of wood surfaces modified with different plasma treatments. The K-values of plasma-treated veneer surfaces at different plasma power levels and with different gases (such as O2, N2, Ar, air, and NH3) were 458% to 653% and 332% to 528% higher than those of untreated veneer surfaces, respectively. In addition, the K-values of the three resins on the oxygen plasma-treated veneer surfaces were 38% to 1204% higher than those on the untreated veneer surfaces. Therefore, this method was helpful for characterizing the dynamic wettability of veneer surfaces modified with plasma treatment.

Improving Water Resistance of Soy-Protein Wood Adhesive by Using Hydrophilic Additives

Soy protein adhesives are good candidates for the replacement of formaldehyde-based adhesives due to environmental concerns. However, poor water resistance has limited their application. This study was conducted to improve the water resistance of a soy-protein adhesive intended for plywood by polyethylene glycol (PEG) with different molecular weights. Ethylene glycol (EG), diethylene glycol (DEG), 400-, 2000-, and 10000-dalton polyethylene glycols were used as additives to soy protein isolate (SPI). The hydrogen bonding interaction, thermal properties, wettabilities on poplar veneer, and adhesion properties of the blended adhesives were investigated. Results showed that improving the wettability and intermolecular hydrogen bonding, induced by ethylene glycol, increased the wet adhesion strength by 30%. Higher-molecular weight polyethylene glycol imposed a decrease in adhesion due to its poor water resistance. Based on the present results, it is proposed to improve the water resistance of soy adhesives by introducing hydrophilic polyols, which also could simultaneously improve surface wetting and wet adhesion.

Preliminary study on the variation of the bending properties of poplar rotary-cut veneer

The authors studied the variability of mechanical properties and density within poplar wood veneer. Determinations (EN 310 1993) were done using a tensometer particularly suitable for test pieces of small dimensions, by means of a 100 daN load cell. The bending test method developed seems to be able to provide reliable results, that confirmed the expected strong influence of the ring portions on both density and MOR (latewood being of course heavier and stronger), a difference which seems, however, less noticeable in false heartwood.

Studies on Poplar Veneer Dyeing with Reactive Yellow Dyes

In this paper, the relationship is studied by spectrophotometric method between the structure of reactive yellow X-R, reactive yellow K-6G, reactive yellow KN-GR, reactive yellow M-5G, reactive yellow M-3RE, reactive yellow EF-3R and their colors, poplar veneer dyeing characteristic parameters S, E, R, F values, exhaustion curves and fixation curves. The results showed that longer conjugated system and better coordination of electron donor and acceptor group and smaller steric hindrance generates longer absorbance wavelength. The S value of six active dyes is reactive yellow X-R> reactive yellow KN-GR> reactive yellow K-6G> reactive yellow M-5G> reactive yellow M-3RE> reactive yellow EF-3R, the R and E and F value is reactive yellow M-3RE> reactive yellow M-5G> reactive yellow EF-3R> reactive yellow X-R> reactive yellow KN-GR> reactive yellow K-6G. The exhaustion and fixation rate is increasing with the increasing of time, except that the exhaustion containing single chlorine-triazine is decreasing within 10min after addition of alkali.

Bonding Properties of Poplar Plywood with High Moisture Content Veneer

The poplar is largest plantation tree species of in China. However, poplar veneer is easily broken when subjected to drying for plywood. This work presents an orthogonal test to reveal the key technological parameters of poplar veneer with high moisture content (MC) on the bonding properties. The results showed that, veneer MC has a significant effect on internal bond (IB) and MC of obtained plywood, but has a light effect on the content of released formaldehyde. Resin content has a significant effect on IB, MC and content of released formaldehyde. Hot-press time has a significant effect on content of released formaldehyde; but has a light effect on MC and IB. The obtained optimal technological parameters of poplar veneer with high moisture content is, veneer MC of 26%, resin content of 11%, and hot-press time of 200s.

Synthesis, Application of a Novel Halogen-Free Intumescent Flame Retardant Agent for Poplar Wood Veneer

A novel non-halogen intumescent flame retardant agent (IFR) was prepared by using phosphoric acid, pentaerythritol and aniline as raw materials, a flame-retardant poplar wood veneer was prepared by treating the veneer with IFR. The influence factors of flame retardant processing technology on poplar wood veneer were studied by the orthogonal experiment. Flammability of the veneer was investigated by Limit Oxygen Index (LOI) test. The optimal impregnated time, impregnated temperature and impregnated concentration of IFR treated poplar wood veneer were 3h, 80°C and 18% respectively, which can make the veneer get the highest LOI of 46.7%.

Surface modification of poplar veneer by means of radio frequency oxygen plasma (RF-OP) to improve interfacial adhesion with urea-formaldehyde resin

Abstract The radio frequency oxygen plasma (RF-OP) treatment of wood was in focus, namely the surface properties of poplar veneer has been analyzed as a function of RF-OP treatment power concerning the chemical composition, free radicals, morphology and roughness. In addition, the interfacial adhesion of plywood composites was measured by determining the shear strength. The results show that RF-OP treatment introduced free radicals and polar groups onto the veneer surface, changed the surface morphology, and increased the surface roughness. Shear strength of the composite was improved. It can be concluded that RF-OP treatment is most effective at the optimal treatment power of 200 W.

Effect of curing technology on bonding properties of silicate wood adhesive

In order to determine the best curing conditions of silicate wood adhesive, three different curing conditions, i.e. room temperature, moderate temperature, and high temperature were chosen to prepare poplar plywood with silicate adhesive and poplar veneer as raw materials. The optimised curing technology was obtained based on a lot of experimental analysis using the single factor test method and orthogonal test method. The research results showed that the curing conditions have obvious influence on the bonding properties. Compared with the samples which were cured at moderate or high temperature, the specimens cured at room temperature have higher bonding strength and water resistance. The dry and wet bonding strength of poplar plywood prepared from optimised curing technology was 0·89 and 0·61 MPa, respectively, and 24 h thickness swelling rate was 5·6%, these properties reached the Chinese National Standard of II Grade Plywood.

Effects of Inhibit Woody Materials Photochromic Coated with Water-Based Paints

The inhibition effect of medium density fiberboard (MDF), particle board, dyed veneer and poplar veneer photochromic coated with water-borne wood paint and wax oil were studied by CIE(1976)L*a*b* color measurement system. The results showed that the specimen surface towards yellowing, lightness reduced, yellow-blue chromatic index rose and color saturation increased. Coating treatment has good inhibition effect on woodiness material photochromic mainly depends on it can significantly inhibit the yellow-blue index increase.

The Influence of Hot Compression on the Surface Characteristics of Poplar Veneer

The surface characteristics of wood veneer are inevitably influenced by hot compression treatment, which is crucial to bonding ability in the production of veneer-based composites such as plywood and laminated veneer lumber (LVL). The objective of this study was to investigate the effect of compression at the temperature of 120 °C on the surface roughness, surface element compositions, and surface free energy (SFE) of poplar veneer. The results showed that the surface roughness of veneer decreased with increasing compression ratio (CR). X-ray photoelectron spectroscopy (XPS) analysis indicated that the oxygen to carbon atoms ratio (O/C ratio) of the veneer surface decreased, while the carbon C1 to C2 atoms ratio (C1/C2 ratio) increased due to hot compression. The SFE of veneer increased by 12% at the CR level of 11%. The improvement in wettability was mainly due to the interfacial contact area increase of the hydrophilic veneer and the decrease in hydrophobic air in the liquid-veneer interface as the CR level increased.

Poplar Wood Veneer Stain Retardant Study the Integration Process

In this study, the use of fire retardant, stain mixed solution using heat, pressure processing poplar veneer, the use of orthogonal experiment to determine the optimal technology mix rationale for poplar veneer: processing retardant, stain veneer process optimization flame retardant concentration of 20%; dye concentration of 0.5%; retardant treatment time 60min.