Wood-based Composite Materials Research Articles

Fluorescent thermochromic wood-based composite phase change materials based on aggregation-induced emission carbon dots for visual solar-thermal energy conversion and storage

Efficient solar-thermal energy conversion and storage is significant to overcome current energy shortage problems. Monitoring solar-thermal energy storage process by an evident and convenient display is conducive to improving energy utilization. Herein, fluorescent thermochromic wood-based composite phase change materials (WPCMs) were constructed for visual solar-thermal energy conversion and storage. It was fabricated by encapsulating polyethylene glycol (PEG) and aggregation-induced emission carbon dots (AIE-CDs) showing blue dispersed emission and red aggregation-induced emission into delignified wood (DW). The DW well-preserved the distinctive anisotropic porous structure and prevented the leakage problem of PEG. The WPCMs possessed great solar-thermal conversion capacity benefitting from strong and broad solar light absorption behaviors of AIE-CDs. Additionally, WPCMs showed real-time and visual fluorescent thermochromic property, it exhibited red AIE, and the fluorescence (FL) decreased and shifted into the blue emission band under solar radiation. The solar-thermal energy conversion and storage led to solid–liquid transformation of WPCMs, which promoted AIE-CDs’ dispersion, thereby changing the FL. It also exhibited a high latent heat of fusion (160.8 J·g−1), favorable stability over 150 heating–cooling cycles, thermal stability below 210 °C and good shape stability. The WPCMs can be extended to applications in energy-saving buildings and optical lighting materials with visual thermal regulation capability.

Evaluation of the Influence of the Conditions of Catalytic Continuous Steam Explosive Activation of Wood on the Physical and Operational Properties of Wooded Composite Materials Based on Activated Fibers

This article presents the results of studies of obtaining wood composite board materials without binders using the method of preliminary steam explosive treatment, as well as an assessment of the impact of impregnation conditions and continuous steam explosive activation of wood on the physical and operational properties of wood-based composite materials based on activated fibers. The rational operating parameters for obtaining board wood-composite materials (WCM) have been determined. We established the influence of impregnation modes (temperature, catalyst concentration), continuous steam explosive treatment with afterwash (temperature, pressure, intensity of mechanical action), as well as the properties of activated lignocellulose fibers (composition and morphological structure) on the operational properties of WCM. The expediency of introducing a catalyst (sodium bisulfite) at the washing stage has been proved, since the introduction of sodium bisulfite during impregnation before steam explosive treatment promotes the formation of lignosulfonates in the activated material, which participate in the formation of the physical properties of WCM.

Analysis of Rotational Stiffness of the Timber Frame Connection

Initially, timber was considered only as an easily accessible and processable material in nature; however, its excellent properties have since become better understood. During the discovery of new building materials and thanks to new technological development processes, industrial processing technologies and gradually drastically decreasing forest areas, wood has become an increasingly neglected material. Load-bearing structures are made mostly of reinforced concrete or steel elements. However, ecological changes, the obvious problems associated with environmental pollution and climate change, are drawing increasing attention to the importance of environmental awareness. These factors are attracting increased attention to wood as a building material. The increased demand for timber as a building material offers the possibility of improving its mechanical and physical properties, and so new wood-based composite materials or new joints of timber structures are being developed to ensure a better load capacity and stiffness of the structure. Therefore, this article deals with the improvement of the frame connection of the timber frame column and a diaphragm beam using mechanical fasteners. In common practice, bolts or a combination of bolts and pins are used for this type of connection. The subject of the research and its motivation was to replace these commonly used fasteners with more modern ones to shorten and simplify the assembly time and to improve the load capacity and rigidity of this type of frame connection.

Microstructure and Hydrophobic Properties of Nano-Cu-Coated Wood-Based Composites by Ultrasonic Pretreatment

The combination of nano-metal and wood to prepare copper-coated wood-based composite materials has important research value and practical significance for improving the function of wood, expanding the application field of wood, and adding added value. In this paper, 31-year-old wood (Pinus sylvestris L. var. mongholica Litv) veneer was taken as the research object. The wood veneer was pretreated by ultrasonic wave, and copper film was deposited on the surface of the wood veneer by magnetron sputtering to prepare “environmentally friendly” copper-plated wood-based composite materials. The microstructure and hydrophobic properties of Cu-coated wood-based composites were characterized and studied. With the increase in coating time, the diffraction peak intensity of wood cellulose gradually decreased, and the diffraction peaks of Cu (111), Cu (200), and Cu (220) of metallic copper appeared. Under the sputtering condition of a substrate temperature of 200 °C, the copper film deposit on the surface of the wood was uniform and densely arranged. The surface water contact angle reached 149.9°. Ultrasonic treatment increases the porous structure of wood, and the rough metal copper film interface was constructed on the surface of wood by magnetron sputtering to transform the surface wettability of the wood from hydrophilic to super-hydrophobic. The lotus leaf effect was realized on the wood surface.

Wood-based composite phase change materials with self-cleaning superhydrophobic surface for thermal energy storage

Form-stable composite phase change materials, as thermal energy storage technology, show great promise for reducing energy consumption and relieving current energy shortage problems. However, porous supporting materials and most phase change materials are hydrophilic and hygroscopic, which cause crack-formation at the interfaces between supporting materials and phase change materials and decrease in thermal energy storage capacity of composite phase change material in wet or humid environment. There are almost no reports concerning this topic. Herein, form-stable and superhydrophobic composite phase change materials are fabricated by spraying superhydrophobic coating on the surface of composite phase change materials, in which delignified wood acts as a supporting material to protect against liquid leakage of 1-tetradecanol. The superhydrophobic composite phase change materials possess large water contact angle of 155° and superhydrophobic stability at 20–100 °C and pH 3–12, which prevents supporting materials and phase change materials from contacting with moisture in wet environment. In addition, the superhydrophobic composite phase change materials exhibit large latent heat of fusion (125.40 J/g), 29.58 J/g higher than that of composite phase change materials without superhydrophobic coating in wet environment. Moreover, the superhydrophobic composite phase change materials possess excellent thermal reliability and stability, efficient solar-to-thermal energy conversion and self-cleaning property, which are potential in the application of advanced energy-related devices and systems for thermal energy storage in wet or humid environment.

Evaluation of Physical, Mechanical Properties and Pollutant Emissions of Wood-Magnesium Laminated Board (WML Board) for Interior Finishing Materials

This study serves as basic research for the development of a new wood-based building finishing material that improved the weakness of inorganic materials such as gypsum board and magnesium board widely used as interior finishing materials and brought out the strength of the wood. The results of evaluating the physical and mechanical properties and the environmental effect related to hazardous substance discharge having manufactured a wood-magnesium laminated composite are as follows. The thermal conductivity and thermal resistance of WML board was improved by about 28~109 percent over magnesium board due to the low thermal conductivity of wood. The adhesive strength of WML board showed a similar result to that of plywood as it exceeds 0.7N/mm2, the adhesive standard of wood veneer which is presented by KS F 3101. Bending strength and screw holding strength were more improved by manufacturing WML board than magnesium board. The WML board manufactured in this study satisfied the criteria for emissions of hazardous substances prescribed in the Indoor Air Quality Control Act, and confirmed the possibility of development as a new wood-based composite material that can replace existing inorganic materials.

Formalizing shape-change: Three-dimensional printed shapes and hygroscopic material transformations

Shape-changing materials have become increasingly popular among architects in designing responsive systems. One of the greatest challenges of designing with these materials is their dynamic nature, which requires architects to design with the fourth dimension, time. This article presents a study that formalizes the shape-changing behavior of three-dimensional printed wood-based composite materials and the rules that serve to compute their shape-change in response to variations in relative humidity. In this research, we first developed custom three-dimensional printing protocols and analyzed the effects of three-dimensional printing parameters on shape-change. We thereafter three-dimensional printed kirigami geometries to amplify hygroscopic material transformation of wood-based composites.

Multifunctional wood based composite phase change materials for magnetic-thermal and solar-thermal energy conversion and storage

In recent years, multifunctional form-stable composite phase change materials have been the research focus in the field of thermal energy storage. In this work, magnetic wood-based composite phase change materials are prepared via the impregnation of a compound of 1-tetradecanol and Fe3O4 nanoparticles into delignified balsa wood. Delignified balsa wood, which has porous structure with low density and high loading content of over 80%, was used as a supporting material. The addition of Fe3O4 nanoparticles provides an excellent magnetic property and improves the solar-to-thermal conversion efficiency of the composite. Benefiting from the magnetothermal effect, the magnetic wood-based composite phase change materials can be heated under an alternating magnetic field. Also, the magnetic wood-based composite phase change materials exhibit large latent heat (179 J/g), excellent thermal reliability after 100 heating-cooling cycles, and outstanding shape stability. And they have good thermal stability below 112 ℃. Considering the easy processing and excellent property, the magnetic wood-based composite phase change materials have great prospect in multifunctional thermal energy storage in practical applications.

Исследование физико-механичес- ких и рентгенозащитных свойств деревокомпозиционного слоистого материала «Фанотрен Б»

Physical and mechanical and x-ray protection properties of new wood-based composite material “Fanotren B”, which consist of alternating layers of peeled birch veneer and reinforcing x-ray protective layers, are studied. The x-ray protective layer is nonwoven fabric – sintepon impregnated with x-ray protective composition; consist of barium sulfate, adhesive based on polyvinyl acetate dispersion and water. The material is recommended to be used in construction and decoration of premises in the areas with high radiation background. A distinctive feature of the developed material is the absence of lead and materials based on it. We had the following research objectives: to study the stress strain behavior of the material; to determine the balanced formulation of saturating composition for the x-ray protective layer; to evaluate its physical and mechanical properties. The stress – strain ratio of the ma-terial was simulated by the finite element method, the physical and mechanical properties were evaluated by the standard methods, the protective properties of the x-ray protective layer were measured by the lead equivalent of the image transparency on the radiograph with the use of lux meter. Theoretical studies have shown that the behavior of metal faced plywood under external load is described by the Sophie Germain’s equation with acceptable accuracy. The modeling was carried out on a solid model, which took into account mechani-cal properties of the materials included in the design and scheme of laying out the veneer layers. The developed model of the stress strain behavior has showed that the decrease of the protective layer thickness leads to the increase of deflections and stresses in it. Computer simulation revealed the stress increase in the areas of bonding the material protective layer and outer side of veneer. The impregnating composition was determined experimentally: mineral filler content is 51 %, binder content is 26 %, and water content is 23 %. The technological modes of composite laminated material formation were determined: binder consumption is 176 g/m2; pressing temperature is 50 oС; gluing time is 8 min. The material with the thickness of 9.5 mm has density of 1600 kg/m3; a lead equivalent is 0.54 mm Pb/mm; cross-breaking strength along the outer layers is 39 MPa; shear strength along the adhesive layer is 1.34 MPa; tensile strength along the fibers is 53 MPa.For citation: Yatsun I.V., Gorokhovskiy A.G., Odintseva S.A. Study of Physical and Mechani-cal and X-Ray Protection Properties of Wood-Based Composite Laminated Material “Fanotren B”. Lesnoy Zhurnal [Forestry Journal], 2019, no. 3, pp. 110–120. DOI: 10.17238/ issn0536-1036.2019.3.110

Various polymeric monomers derived from renewable rosin for the modification of fast-growing poplar wood

The incorporation of polymers derived from renewable resources is more desirable in the preparation of wood composites due to its sustainability. As biomass feedstock, rosin has been used for the preparation of wood-based composite material. However, the high leachability and non-reactive with wood limit its application. Three kinds of rosin derivatives synthesized with reactive groups in the current study were confirmed by 13C NMR and Fourier transform infrared spectroscopy. The polymerization process and polymer properties of the derivatives were studied by the differential scanning calorimetry and gel permeation chromatography. The poplar wood was impregnated by rosin derivatives solution and then oven heated to induce in situ polymerization. The results indicated that the derivatives could penetrate into wood structures, polymerize in both wood cell walls and lumina, and efficiently improve the physical properties and surface hardness of wood. Moreover, the extraction indicated that rosin derivatives could permanently bulk wood structure through the formation of polymers. Our studies provide a new approach to modify fast-growing wood using renewable resources.

Low-cost, three-dimension, high thermal conductivity, carbonized wood-based composite phase change materials for thermal energy storage

Thermal energy storage is important for energy saving and social developing. Low-cost, high thermal conductivity, form-stable composite phase change materials are urgent in energy storage and management. In this work, a novel carbonized wood-based composite phase change materials (TDCW) are fabricated by impregnating of 1-tetradecanol (TD) into carbonized wood (CW). CW as supporting material exhibits porous three-dimensional (3D) structure, high specific surface area and high thermal conductivity. In addition, compared with conventional graphene, carbon nanotubes and other one-dimensional (1D) or two-dimensional (2D) carbon materials, CW is inexpensive and has higher loading content of 73.4 wt%. What's more, CW as supporting material is firstly used in composite phase change materials. According to differential scanning calorimetry measurement and thermogravimetric analysis, TDCW possesses high latent heat, good thermal reliability and favorable thermal stability. In addition, thermal conductivities of PW, CW, TDCW measured at axial direction are all higher than that at radial direction and the thermal conductivity of TDCW is 0.669 Wm−1K−1 at axial direction at 50 °C, which is 114% higher than that of pure TD. The results of thermal conductivity and surface temperature variation collected by infrared thermal camera under heating and cooling process demonstrate that TDCW is beneficial for thermal management application. This work not only provides a novel and superior supporting material, but also prepares a suitable phase change temperature, high latent heat and high thermal conductivity composite phase change material for thermal energy storage and management civil applications.

In-Plane Shear Properties of Laminated Wood from Tension and Compression Tests of Angle-Ply Laminates

AbstractExperimental methods for the characterization of shear strength and stiffness of both wood-based and glass-based or carbon-based composite materials are highly contested because shear prope...

Development of Veneer-based Corrugated Composites, Part 1: Manufacture and Basic Material Properties

Typically, wood-based composite materials have been developed through empirical studies. In these products, the constituent wood elements have broad spectrums regarding species, size, and anatomical orientation relative to their own dimensions. To define special strength and stiffness properties during a long-term study, two types of corrugated wood composite panels were developed for possible structural utilization. The constitutional elements of the newly developed products included Appalachian hardwood veneer residues (side clippings) and/or rejected low quality, sliced veneer sheets. The proposed primary usage of these veneer-based panels is in applications where the edgewise loading may cause buckling (e.g., web elements of I-joists, shear-wall and composite beam core materials). This paper describes the development of flat and corrugated panels, including furnish preparations and laboratory-scale manufacturing processes as well as the determination of key mechanical properties. According to the results in parallel to grain direction bending, tension and compression strengths exceeded other structural panels’ similar characteristics, while the rigidities were comparable. Based on the research findings, sliced veneer clipping waste can be transformed into structural panels or used as reinforcement elements in beams and sandwich-type products.

Creation of density distribution charts in the cross and axial section of a tree trunk- Short Communication

The purpose of this paper is to develop a method of constructing density distribution charts in roundwood log based on the density values obtained with a resistograph. The problem of improving the performance properties of structures made of wood and wood-based composite materials and laminated products is particularly relevant for construction in the northern regions. The experience of building in Yakutia shows sufficient reliability and durability of structures made of larch wood, despite the fact that their use is associated with technological challenges: larch planks warp and crack during the drying process; rigidity of wood increases. These disadvantages are caused by the structural features of the wood material; the degree of their intensity is proportional to the index of wood density. This paper presents the methods and results of qualitative research on wood indices obtained in laboratory and field conditions, as well as the authors' methods of graphical representation of density distribution in the cross and axial sections of a tree trunk, which are based on measurements taken via the method of oriented drilling. In the experimental studies, we performed a comparative analysis of the two-dimensional charts of density distribution with the charts of velocity distribution of acoustic pulses produced by a sonic tomograph "Arbotom". The elaborated method of evaluating the quality indicators of forest resources contributes to the expansion of the boundaries of wood-based material utilization, reduces their cost and improves the quality of construction of wooden structures and buildings.

Production and mechanical performance of scrimber composite manufactured from poplar wood for structural applications

The use of wood-based composite material for structural purposes is of increasing interest. A scrimber composite, which is manufactured from thermally modified fast-growing wood, is introduced in this paper. The production of such scrimber is able to reduce the inherent variability in mechanical properties of natural wood material, and also allows the effective utilization of fast-growing wood, which is widely available with a low price in China. Experimental tests were conducted to determine the mechanical properties of the scrimber composite. A comparison of mechanical properties of the proposed scrimber composite with other timber/bamboo-based materials is then reported. It is shown that the scrimber composite has desirable mechanical performance as a construction material, which is comparable or superior to those of engineered timber/bamboo products. This study contributes to a potential utilization of fast-growing tree species, and the presented mechanical tests can serve as a fundamental basis for more applications of such composite material in practical engineering.

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.

Comparison of Wood Composite Properties Using Cantilever-Beam Bending

Wood-based composite panels generally are first tested out-of-plane in the primary panel direction followed by the cross panel direction, but rarely edgewise. While most applications use wood-based composites in the flat-wise orientation and only need the out-of-plane properties, there are construction configurations where edgewise properties are needed for improved design configurations. A square cantilever beam was used to determine the apparent stiffness (EI) and modulus of elasticity (E) differences for 3 wood-based composite panel materials. Specimens were cut along the primary panel direction or machine direction (MD) and perpendicular to the primary direction or cross-machine direction (CD). The square specimens were first non-destructively tested oriented in the normal or out-of-plane position, then rotated 90 degrees to measure edgewise properties. The results for a 20 mm thick medium density fiberboard (MDF) showed that the MD properties were 56% higher than the CD properties. The other two composite materials, 12 mm thick particleboard (PB) and 12 mm thick MDF, were essentially the same in the MD or CD directions. For all the materials, the differences between the out-of-plane and the edgewise loading directions showed higher EI and E between 17 to 61%, respectively. The largest difference was found in the PB composite material properties that were between 42 to 61% higher for the out-of-plane properties. For the 12 and 20 mm thick MDF material, in-plane properties were 27 to 33% and 17 to 23% higher, respectively. The cantilever bending method was able to quickly assess the difference using the same specimen.

Effect of loading ratio, conditioning time and air exchange rate on the formaldehyde emission from wood-based board using large chamber and desiccator method

The emission of formaldehyde is critical factor in the evaluation of environment and health effects of wood-based composite materials. Different test methods are used in different countries. The comparison study was done between commonly used American test methods, large chamber ASTM E1333-10, and Japanese desiccator method JIS A 1460-2001 for testing Formaldehyde emission form 16mm uncoated particleboard and medium density fiberboard (MDF) under the different conditioning days, air exchange rates, and loading ratios.In case of reduction of the loading ratios, the good correlation between the large chamber method and the desiccator test could be obtained for particleboard tested. With the reduction of the loading ratios, the correlation between the large chamber method and the desiccator test was improved. At the loading ratio of 0.04ft2/ft3, the coefficients of determination (R2) showed 0.995 for 0.5 AC/HR, and 0.989 for 1.0 AC/HR. Large chamber emission rate at 1.0 AC/HR was 0.727 time Large chamber emission rate at 0.5 AC/HR.

Composite films from spruce galactoglucomannans with microfibrillated spruce wood cellulose

Two future wood biorefinery products, spruce galactoglucomannans (GGM) and microfibrillated spruce wood cellulose (MFC), were mixed to form composite films. The films were plasticized with different amounts of glycerol, and the preparation of films was successful even with low glycerol contents. The film properties were studied using optical microscopy and scanning electron microscopy, x-ray diffraction, water sorption, dielectric analysis, moisture scanning dynamic mechanical analysis, and tensile testing. The addition of MFC clearly affected the properties of the films by decreasing the moisture uptake and increasing the relative humidity of softening of the films and by increasing the glass transition temperature, tensile strength, and Young’s modulus of the films. The effect of MFC addition on the tensile properties of films was emphasized at low glycerol contents. The addition of MFC did not affect the degree of crystallinity of GGM in the films, which was between 20 and 25%. MFC can be efficiently used as reinforcement of GGM films to form wood-based composite materials and to prepare GGM-based films and coatings with low plasticizer content.

Optimization of a Pressing Diagram in OSB Pressing

This paper summarizes the results of a pressing diagram optimization based on changes in pres- sure, temperature and distance between frames of a continuous during Oriented Strand Boards (OSB) press- ing. Tests of selected mechanical properties were carried out on OSB/3 boards with a nominal thickness of 18 mm - a basic type with urea-formaldehyd (UF) glue in surface layers and isocyanate glue (PMDI) in the central layer and further an ECO type with PMDI glue in all layers produced by a prominent manufacturer of OSB boards in the Czech Republic. OSB/3 boards are intended for structural purposes for use in wet environments. Changes in the pressing diagram were carried out at the stage of press opening, which signifi cantly affects mechanical and physical properties of OSB boards. In order to be able to compare the effects of changes in the pressing curve, the same setting of production parameters was used with all tested boards. The results of laboratory tests were compared with the values given in the CSN EN 300 Standard. Optimization of the pressing process ranks among the most effective measures to increase the quality of particle boards at zero or minimum costs. The control of pro- duction processes is increasingly perfect thanks to the development of electronics, control and computer technol- ogy. At present, not only in our country but also worldwide, marked development of wooden constructions occurs thanks to the development of new types of wood-based composite materials and to the development of technologies in building industry. OSB boards are an important representative of wood-based composite materials for wooden constructions. As compared to natural material, OSB boards show a homogenous structure not including natural defects typical of solid wood. From the point of view of physical and mechanical properties, OSB boards are of orthotropic character.