Wood-based Composites Research Articles

Investigating the possibility of geopolymer to produce inorganic-bonded wood composites for multifunctional construction material – A Review

Wood-based composites are widely used in consumer products, either in structural or non-structural applications. One of the basic elements for wood-based composites is the binder itself. Recent years have seen great development and trends in the field of eco-friendly binders in wood-based composite. There have been many concerns on the effects of formaldehyde and volatile organic compounds (VOC) released from wood-based products. Researchers have put lot of effort into developing environmental friendly products with enhanced sustainability. Binder materials with a focus on geopolymers (i.e., alumino-silicates) are discussed in this publication. The development and utilization of geopolymeric binders is relatively new in the field of wood-based composites. Up to the present there has been insufficient information regarding the manufacturing conditions and properties of wood-nonwood composite materials prepared using a geopolymeric binder. This paper considers the background of geopolymer materials and the possibilities of producing inorganic-bonded wood composite using geopolymer.

Properties of Lignocellulosic Composites Containing Regenerated Cellulose Fibers

The aim of the paper was to examine the application of regenerated cellulose fibers as a reinforcement material in particleboard production. Single-layer, 10 mm thick panels, with the density of 800 kg/m3 were produced with addition of regenerated cellulose fibers in the range of 0 do 15% by mass during panels’ production. The mechanical and physical parameters of the produced panels were tested, as well as work of fracture. The results showed that addition of regenerated cellulose fibers to the structure of wood-based composite did not improve their modulus of rupture, modulus of elasticity, or internal bond. The physical parameters of the produced panels (water absorptivity, swelling in thickness when soaking) also were reduced. The work of fracture of the tested panels increased with increasing content of regenerated cellulose fibers. A strong linear regression between work of fracture and regenerated cellulose fibers content was observed.

Electromagnetic shielding wood-based composite from electroless plating corrosion-resistant Ni–Cu–P coatings on Fraxinus mandshurica veneer

A novel and simple electroless Ni–Cu–P plating process was used for preparing corrosion-resistant and electromagnetic interference shielding wood-based composite. The effects of CuSO4·5H2O concentration, pH value in the plating solution and operation temperature on the metal deposition, surface resistivity, chemical composition, corrosion resistance and surface morphology of the composite were investigated. The surface morphologies were observed by using scanning electron microscopy and the chemical compositions were analyzed by X-ray energy dispersive spectrometer. The electromagnetic shielding effectiveness (ESE) was measured by spectrum analyzer. The corrosion resistance was evaluated by potentiodynamic corrosion measurement. The results show that metal deposition increases with pH value and temperature increase; however, it decreases with CuSO4·5H2O concentration increase. The corrosion resistance of the plated Ni–Cu–P coatings obviously depends on the total content of Cu and P in the coating. Higher total content of Cu and P leads to higher corrosion resistance. The optimum conditions are as follows: CuSO4·5H2O concentration of 1.0 g/L, pH value of 9.5, and operation temperature of 90 °C. The obtained coating contains 77.41 % Ni, 8.96 % Cu, and 13.63 % P. The wood-based composite exhibits higher corrosion resistance and ESE of around 60 dB in frequencies ranging from 9 kHz to 1.5 GHz. In this paper, a promising process for corrosion-resistant and electromagnetic shielding wood-based composites was developed.

A new quantitative method for evaluation of adhesive penetration pattern in particulate wood-based composites: elemental counting method

The importance of adhesion in production of wood-based composites is well-known. Adhesive penetration and interphase morphology play an important role in bond strength and product performance. Many studies offered different methods for interphase characterization and analysis. Both qualitative and quantitative methods have been used to analyze the bondline. Most of the quantitative methods were developed for bonded assemblies of veneer or wood blocks. Adhesive penetration measurement in particulate wood-based composites is the main scope of this study. For this purpose, uniform oriented strand board with veneer strands was produced by the use of phenol formaldehyde resin with 2, 6, and 10 % strand moisture content (MC). The strands were formed into well-organized mats to achieve a uniform structure for the composite. Cross-section specimens were prepared from each board and observed by epifluorescence microscopy. Six positions for growth-ring angle in adhesive joints were denoted to evaluate penetration in different directions of the wood. Four parameters were also determined to quantify resin penetration patterns by counting the quantity of the main anatomical elements of wood, which were filled with resin. Finally, it was determined that this method could recognize the differences between adhesive penetration in boards produced with different level of strand MC. Resin penetration in strands with 6 and 10 % MC was the greatest. Growth-ring angle of the strands influenced penetration as it was increased when both strands meet each other in an oblique position, although this effect was significant only in maximum penetration depth in fibers.

Effect of CuSO4 Content in the Plating Bath on the Properties of Composites from Electroless Plating of Ni-Cu-P on Birch Veneer

A wood-based composite was prepared via simple electroless Ni-Cu-P plating on birch veneer for EMI shielding. The effects of CuSO4•5H2O concentration on the metal deposition, elemental composition, phase structure, surface morphology, wettability, surface resistivity, and shielding effectiveness of coatings were investigated. The coatings were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). When the CuSO4•5H2O concentration was increased from 0.6 g/L to 2.2 g/L, the metal deposition was decreased from 79.61 g/m2 to 66.44 g/m2. Elemental composition showed that the copper content in the coating increased significantly, whereas the nickel content was reduced significantly and the phosphorus content was slightly reduced. The crystallinity of coatings increased, and fine-grain structure was observed, with higher copper content. Ni-Cu-P deposition improved the hydrophobic properties when the maximum static contact angle increased from 77.5° to 116.5°. The lowest surface resistivity was 367.5 mΩ/cm2, and the EMI shielding effectiveness of Ni-Cu-P-coated veneers was higher than 60 dB in frequencies ranging from 9 kHz to 1.5 GHz.

High Compressive Strength of Palm Oil Empty Fruit Bunches (<i>Elaeis guineensis</i>) Composites

Simple mixing and hot pressing methods were used to make high strength and light-weight composite from oil palm empty fruit bunches (OPEFB) using PVAc as an adhesive and silica nanoparticles as a filler. The mechanical strength of the composite was examined in term of compressive strength. The simple mixing method was used to mix composition with PVAc and silica nanoparticles. Silica nanoparticles were added as filler. Hot pressing method was used to press the mixed composites at a pressing pressure of 85 MPa, pressing temperature of 150 °C, and pressing time of 20 minutes. The optimum composition in term of compressive strength for the strongest composite had a mass ratio of OPEFB/PVAc of 13 : 2 and obtained a compressive strength of 82,88 MPa. Higher compressive strength of 100,39 MPa was obtained by adding the silica nanoparticles at a mass ratio of OPEFB/PVAc/silica nanoparticles of 13 : 2 : 0,75. At pressing pressure of 100 MPa, pressing temperature of 150 °C, and pressing time of 20 minutes, we found compressive strength of 115,35 MPa. Data analysis of XRD showed that the used silica nanoparticles were in amorphous phase or had broad pattern. The compressive strength data showed that the composites were stronger than the composites made by Masturi and Kumagizuri, and also stronger than the ordinary wood-based composites. Thus, the composites are feasible to be used to replace wood-based composites, especially in furnishings.

A review of high R-value wood framed and composite wood wall technologies using advanced insulation techniques

The main objective of this study is to indentify advanced wall frame assemblies applicable for residential and small commercial buildings, that have or could reach R-values larger than RSI – 3.5m2K/W (U-value lower from 0.29). An extensive literature review of existing and past practices is used as the main vehicle to analyze: framing and wall insulation methods, architectural details with focus on minimizing thermal bridges, structural adequacy aspects with respect to gravity and lateral loads, and ability to provide fire and sound breaks. In this paper a wide selection of advance framing wall assemblies is discussed in details with main focus on construction methods, architectural details with minimized thermal bridges, and structural (strength) concerns. High performance wall technologies of consideration include: double walls, Larsen truss walls, optimum or advanced framing walls, walls using distance spacers (furring) and walls made of wood-based composites. Since wood framing for wall applications is mostly used in North America, Scandinavia, and Central Europe, this study is focused on research studies from these regions. In addition, field test studies are presented discussing an application of high R-value of new and retrofitted wall assemblies in actual test houses that have been constructed and being currently monitored.

Comparative Study of Bond Strength of Formaldehyde and Soya based Adhesive in Wood Fibre Plywood

Plywoods, particleboards and medium density fibreboards are currently used in the construction of houses, furniture, partitions, etc. These usually incorporate some form of formaldehyde as part of the adhesive system. Formaldehyde-based adhesives are known to be harmful as formaldehyde emissions during manufacture and after installation are known to be carcinogenic and have other undesirable health effects. This and other environmental concerns have in the recent past led to an interest in ‘green’ adhesives from biological sources that are sustainable and environmentally friendly. Green adhesives are one of the green building practices, which aim to construct buildings that are environmentally responsible, economically viable and healthy places to live and work. The objective of this investigation was to explore environmentally friendly biobased adhesives for plywood manufacturing. This study proposes a natural biobased adhesive that was developed using soya flour, phenol, Plaster of Paris and an agro-based powder as the binder. A comparison of modulus of rupture of the plywood developed using the proposed soya-based adhesive with popular plywoods, including the traditional urea-formaldehyde based plywood has also been undertaken. The three-point bend test (to identify the modulus of rupture) was conducted for all the plywoods compressed at a fixed pressure. It was observed that the soya-based adhesive imparts greater strength to the plywood than the formaldehyde-based adhesive. It is also desirable for wood and wood-based composites to have fire-retarding and microbial-resistant properties by utilising non- toxic additives and treatments. Traditional methods of achieving these objectives have been harmful; for example, timber has been treated with arsenic-based chemicals to make it resistant to microbes. This paper also presents future research directions to render wood-based composites free of toxic additives as well as being sustainable and environmentally friendly.

The influence of scavengers on VOC emissions in particleboards made from pine and poplar

This paper studies the performance of scavengers on Volatile Organic Compound (VOC) emissions from wood-based composites. Particleboards made from maritime pine (Pinus pinaster Ait.) and European poplar (Populus spp.) were produced with a UF resin doped with melamine and two scavengers, sodium metabisulfite and urea. VOC emission was measured according to EN ISO 16000. Particleboards made from pine present much higher total VOC (TVOC) emissions than boards made from poplar. Pine emits a higher amount of terpenes, but also aldehydes, acids and terpenoids, while poplar emits mainly acetic acid. Sodium metabisulfite showed an excellent ability to reduce aldehydes emission, which represents nearly 50 % of total emission of particleboards made from pine. When sodium metabisulfite was applied to particleboards made from poplar, reduction of TVOCs was not significant due to the low contribution of aldehydes to TVOCs. Urea presents a low reduction in TVOCs for both wood species.

Curing kinetics of nano cupric oxide (CuO)-modified PF resin as wood adhesive: effect of surfactant

The effect of nano cupric oxide (CuO) in combination with surfactants on the curing kinetics of phenol-formaldehyde (PF) resin, as well as the bonding strength of plywood prepared using the modified resin was investigated in this study using dynamic and isothermal differential scanning calorimetry. The result showed that the incorporation of nano CuO along with alkane surfactant made in the laboratory clearly reduced the apparent activation energy of the PF resin and improved the addition and condensation reactions of the PF resin. Inclusion of the surfactant had the further effect of compensating the influence of diffusion control caused by nano CuO alone. The shear strength of plywood suggested that the addition of nano CuO (1%) alone or in combination with alkane surfactant (0.55%) or sodium lignosulfonate (0.55%) in the PF resin mixture was sufficient to meet the requirement of wood-based composites manufacturing.

Preparation of EMI Shielding and Corrosion-Resistant Composite Based on Electroless Ni-Cu-P Coated Wood

A simple electroless Ni-Cu-P plating process for preparing an EMI-shielding and corrosion-resistant wood-based composite has been developed. The effects of solution pH value on the metal deposition, surface resistivity, chemical composition, anti-corrosion properties, and crystal structure of the coatings were studied. The coatings were characterized using X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. When the solution pH was increased from 8.5 to 10.0, the metal deposition increased and the surface resistivity decreased. Chemical composition indicated that the nickel deposition increased, whereas the opposite effect was obtained on copper and phosphorus elements with a pH increase from 9.0 to 10.0, and the crystal structure of the Ni-Cu-P coatings changed from an amorphous state to a microcrystalline one. Tafel curves of the Ni-Cu-P coatings prepared at pH 9.0 or 9.5 showed that they had excellent anti-corrosion properties in a 3.5 wt% NaCl solution. The morphology of the coating containing 69.86% Ni - 7.65% Cu - 22.49% P is superior to that with 75.99% Ni - 6.60% Cu - 17.41% P after corrosion tests. The plated birch veneers exhibited electromagnetic shielding effectiveness higher than 58 dB in frequencies ranging from 9 KHz to 1.5 GHz, and the coating firmly adhered to the wood surface.

A Comparative Study on the Inhibitory Ability of Various Wood-Based Composites against Harmful Biological Species

Japanese pine sawyer beetle, pine shoot beetle, and Formosan subterranean termite were selected to investigate the inhibitory abilities of solid wood and wood-based composites (MDF and WPCs) made with Eucalyptus urograndis and Melaleuca leucadendra. The chemical components in the extractives of the two types of wood were also analyzed by GC-MS. The results indicated that the inhibitory ability can generally be listed in descending order as WPCs, MDF, and solid wood when made by the same wood filler. However, samples in each group made using Melaleuca leucadendra exhibited a higher inhibitory level than samples made using Eucalyptus urograndis. 2,3-dihydro-2,2-dimethyl-3,7-benzofurandiol, which was identified in the extractives of both woods (14.169% in Eucalyptus urograndis and 12.686% in Melaleuca leucadendra), was a significant factor for inhibition due to its high toxicity to insects. The chemical components with greatest potential for inhibition were stigmast-4-en-3-one (8.656%) in Eucalyptus urograndis and both 3-demethyl-colchicine (2.642%) and squalene (1.649%) in Melaleuca leucadendra. Additionally, perlite-based MDF showed the best inhibitory ability, possibly because the alimentary of the insects are prone to injury by perlite. PVC-based WPCs had a greater inhibitory level than HDPE-based WPCs due to the presence of the Cl element in PVC, as well as the addition of calcium zinc stabilizer and inorganic filler.

Evaluation of Formaldehyde Emissions and Combustion Behaviors of Wood-Based Composites Subjected to Different Surface Finishing Methods

To use wood-based panels as a final product, they must undergo surface finishing via various processes, such as low pressure laminate (LPL), polyvinyl chloride (PVC), coating paper (CP), direct coating (DC), or veneer overlay/UV coating (VO-UVC). Tests were conducted to look for any reduction of formaldehyde emissions and in combustion behaviors with the use of five different surface finishing methods. To determine formaldehyde emissions, the desiccator method was used according to the Korean Standard KS M 1998. The combustion behaviors of wood-based panels were investigated using a cone calorimeter. The formaldehyde emissions of VO-UVC were lower than those of the other methods. In the burning tests, the heat release rate (HRR) with DC was higher than that with the other methods. The mass loss rate (MLR) when the product with DC was burned was higher than that for the other finishing materials.

Research on the Preparation of Wood-Based Composite Materials Using Wood Processing Residues

Cellulose is one of the most abundant renewable resources on the earth and could meet the increasing demand for environmental protection property and biocompatibility of materials. In recent years, ionic liquid, as a new type of environmentally-friendly medium and soft functional material, has gained widespread concern, for it has provided broad space for the further development of cellulose chemistry. This paper selects 1 - propenyl-3 - methylimidazolium ionic liquid to dissolve and reproduce the cellulose, thereby preparing the gel-type wood-based composite. The reformed fiber bundles constitute an unclosed three-dimensional cross-linked network as the support frame which owns the microstructure similar to balsa wood as well as the stable chemical and physical properties. Its oven dry density is 0.221 g/cm3 and the porosity is over 87%. This kind of gel-type wood-based composite prepared by the green chemical processing could fix and store the carbon adsorbed by trees, which is conductive for the environmental protection.

Preparation and characterization of wood-plastic plywood bonded with high density polyethylene film

This paper presents a study on the potential use of high density polyethylene (HDPE) film as wood adhesive for formaldehyde-free plywood. The physical–mechanical properties of the plywood, including thickness swelling (TS), water absorption (WA), tensile shear strength, modulus of elasticity and modulus of rupture were evaluated. Results show that HDPE film dosage positively affects the properties when ranging from 61.6 to 246 g/m2. The performance of these panels was comparable to those of plywood made with commercial urea–formaldehyde (UF) resins. Comparisons of the dimensional stability between the two plywood demonstrated that 7-day TS and WA values of the panels bonded with UF resins were 5.10 and 23.5 % higher than those bonded with HDPE film, confirming the suitability of HDPE for the use as adhesive in wood-based composites intended for indoor applications subjected to high moisture. DMA tests show that HDPE bonded plywood was significantly inferior in thermal stability at 120 °C and above while it presented almost the same dynamic mechanical properties as UF plywood when the temperature was lower than 100 °C, making it suitable to be used as geothermal floor.

A product semantic study of the influence of the sense of touch on the evaluation of wood-based materials

Based on product semantics, this study investigated how the tactile attributes of wood and wood-based composites are perceived and interpreted semantically. The wood-based samples included ash, birch, elm, oak, pine, OSB (oriented strand board), two wood pulp-reinforced polylactide composites, Comp A and B and one wood–fiber reinforced polypropene composite, Comp C. The subjects rated the samples by the descriptive words natural, exclusive, eco-friendly, rough, inexpensive, reliable, warm, modern, snug and solid. The most significant differences between the samples were found for roughness and for the descriptors, reliable, natural and solid. A principal component analysis yielded three attributes based on the tactile perceptions: reliable, old-fashioned and smooth. The solid wood pieces were perceived as natural and oak was perceived as being exclusive. The composite materials presented a greater variation in terms of perceived attributes than the wood specimens.

Development of Wood-Based Composites Material for 3D Printing Process

This paper presents the development of wood-based composites material for 3D Printing process. The aim is to characterize the waste material from wood powder (WD) as an alternative material and low cost production for rapid prototyping product. The powder blends containing wood powder (90-120µm) with commercial ZP102 material from Z Corporation was used as the composite material. The materials were mechanically blended to produce composition of WD/ZP102(vol.%) 25:70, 50:50 and 75:25 respectively. The material was successfully processed on 3D printers machine, to produce three-dimensional components and followed by post-treatment with ZMax solution to enhance the mechanical properties. The mechanical properties, dimensional accuracy and surface quality of the components were evaluated and the results were compared with the standard ZP102 material. The result shows that the mechanical properties improved with the increased of wood powder content up to 50 (vol.%). However, dimensional accuracy and surface quality were decreased as the wood content increased. Further work on powder preparation is continued for surface quality improvement.

Assessment on emission of volatile organic compounds and formaldehyde from building materials

This paper assesses the reproducibility of testing formaldehyde and VOCs (volatile organic compounds) emissions from wood-based composites such as MDF (medium density fiberboard), hardboard, plywood, coated and raw particleboards, planed pine lumber, and gypsum board. Sawdust and shavings were also included in the study. With the help of a special device, air was sucked from the surfaces of the materials and then was adsorbed on charcoal and Tenax tubes. The adsorbed VOCs were determined by gas chromatography/mass spectrometry. The emission of formaldehyde was determined separately with Interscan Toxic Gas analyzer and chamber method.The results showed that the most emitted VOCs were terpenes, aldehydes, and aromatics. Pine wood plank revealed the highest VOCs (approximately 900μg/m3). Fresh particleboard showed the second highest value with 450μg/m3. The VOC value of other examined materials were 80–170μg/m3.The composition of the emitted compounds was remarkably similar among the different materials. The low VOC emission from the board materials investigated did not verify the hypothesis that these materials provided a tangible contribution to VOCs in the indoor air.Emission of formaldehyde from the board materials studied was very low with an exception. The exception was MDF with an emission value of 0.63mg/m3 formaldehyde whereas all the other materials examined had values around 0.05mg/m3 or appreciably lower.

Effects of post-treatment with alkaline copper quat and copper azole on the mechanical properties of wood-based composites

The static bending strengths, modulus of rupture, and modulus of elasticity of 5 commercial wood-based composites [softwood plywood (SWP), hardwood plywood (HWP), medium density fiber-board (MDF), oriented strand board (OSB), and particleboard (PB)] were measured after a postmanufacture treatment of vacuum-impregnation with alkaline copper quat (ACQ) and copper azole (CA) (target retentions: 0.65, 1.30, and 2.60 kg m-3 for ACQ; 0.25, 0.50, and 1.0 kg m-3 for CA). Of the composites tested, SWP exceptionally sustained no damage to its bending strengths, regardless of preservative types and retentions. Others (HWP, MDF, OSB, and PB) were necessarily affected to some degree by posttreatments. In accordance with the dimensional stability and resistance to biological attacks, of the posttreated composites, SWP seems most suitable and implemental for posttreatment when the appropriate selection of treatment concentrations and schedules is made.

Agricultural and Industrial Valorization of Arundo donax L.

Some agricultural and industrial characteristics of different parts of the giant reed (Arundo donax L.) were studied in this work to evaluate their capacity as growing media and for the manufacturing of the insulating board employed in the building sector. Three different particle sizes (>0.25, 1–2, and 2–4 mm) of the stem and rhizome of Arundo donax L. (SAD and RAD, respectively) were evaluated on bulk density (BD), total pore space (TPS), air capacity, easily available water (EAW), water buffering capacity (WBC), total water-holding capacity (TWHC), shrinkage, total organic carbon (TOC), total nitrogen (TN), and macro- and microelements. Moreover, density, bending strength, internal bond strength, screw-holding strength, and thermal conductivity were determined in boards manufactured with three different particle sizes (>0.25, 1–2, and 2–4 mm) of the stem of Arundo donax. The manufacturing conditions of these boards were three different press pressures (15.7, 21.0, and 26.0 kg cm−2) and two press temperatures (120 and 140 °C). With respect to the agricultural value of this vegetative species, most of physical properties were not inside the interval of values for an ideal substrate. Bulk density, TPS, air capacity, and EAW values were greater in SAD substrates than those of RAD-based media. In general, the particle size of different parts of the giant reed had a significant effect on the physical parameters studied. The macro- and microelement contents were low in comparison to peat, except in the cases of K in both substrates types (SAD and RAD) and TN in RAD substrates. In general, no great differences were observed in the chemical properties related to the particle size of media used. On the other hand, the physical and mechanical properties of the fiberboards from giant reed were comparable to those of the wood-based composites, and the thermal conductivity of these boards was similar to that of other environmentally friendly fiberboards. Mechanical and physical properties of the boards were more significantly affected by the particle size and press pressure than by the press temperature.