Wood Template Research Articles

Hierarchical porosity inherited by natural sources affects the mechanical and biological behaviour of bone scaffolds

A 3-D porous apatite scaffold (B-HA), recently obtained through biomorphic transformation of a natural wood, is investigated on its multi-scale porous structure determining superior biological and mechanical behaviour. B-HA shows a hierarchically organized architecture with wide aligned channels interconnected with smaller tubules, thus recapitulating in detail the lymphatic network of the original wood template. As induced by its biomimetic architecture, B-HA displays values of tensile/compressive strengths and stiffness, higher than values usually measured in sintered ceramics with isotropic porosity. Furthermore, B-HA shows uncommon toughness for a pure ceramic body, plus a tensile/compressive-strength ratio higher than one, so that the material occupies a zone in the Ashby map where ceramics are normally absent. From biological viewpoint, cell co-culture tests in bioreactor are shown to report encouraging results in enhancing the complex tissue regeneration process, thus making B-HA promising as a scaffold able to promote bone regeneration, particularly for large bone defects.

Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects.

Transparent wood (TW) is an emerging optical material combining high optical transmittance and haze for structural applications. Unlike nonscattering absorbing media, the thickness dependence of light transmittance for TW is complicated because optical losses are also related to increased photon path length from multiple scattering. In the present study, starting from photon diffusion equation, it is found that the angle-integrated total light transmittance of TW has an exponentially decaying dependence on sample thickness. The expression reveals an attenuation coefficient which depends not only on the absorption coefficient but also on the diffusion coefficient. The total transmittance and thickness were measured for a range of TW samples, from both acetylated and nonacetylated balsa wood templates, and were fitted according to the derived relationship. The fitting gives a lower attenuation coefficient for the acetylated TW compared to the nonacetylated one. The lower attenuation coefficient for the acetylated TW is attributed to its lower scattering coefficient or correspondingly lower haze. The attenuation constant resulted from our model hence can serve as a singular material parameter that facilitates cross-comparison of different sample types, at even different thicknesses, when total optical transmittance is concerned. The model was verified with two other TWs (ash and birch) and is in general applicable to other scattering media.

Optical Properties and Mechanical Modeling of Acetylated Transparent Wood Composite Laminates.

Transparent wood composites (TWCs) are a new class of light-transmitting wood-based materials composed of a delignified wood template that is infiltrated with a refractive- index-matched polymer resin. Recent research has focused primarily on the fabrication and characterization of single-ply TWCs. However, multi-ply composite laminates are of interest due to the mechanical advantages they impart compared to the single ply. In this work, 1- and 2-ply [0°/90°] TWC laminates were fabricated using a delignified wood template (C) and an acetylated delignified wood template (AC). The optical and mechanical properties of resultant C and AC TWC laminates were determined using ultraviolet-visible spectroscopy (UV-Vis) and tensile testing (5× replicates), respectively. In addition, the ability of classical lamination plate theory and simple rule of mixtures to predict multi-ply tensile modulus and strength, respectively, from ply-level mechanical properties were investigated and are reported herein. Experimental results highlight tradeoffs that exist between the mechanical and optical responses of both unmodified and chemically modified TWCs. Template acetylation reduced the stiffness and strength in the 0° fiber direction by 2.4 GPa and 58.9 MPa, respectively, compared to the unmodified samples. At high wavelengths of light (>515 nm), AC samples exhibited higher transmittance than the C samples. Above 687 nm, the 2-ply AC sample exhibited a higher transmittance than the 1-ply C sample, indicating that thickness-dependent optical constraints can be overcome with improved interfacial interactions. Finally, both predictive models were successful in predicting the elastic modulus and tensile strength response for the 2-ply C and AC samples.

Energy saving wood composite with temperature regulatory ability and thermoresponsive performance

Energy saving materials are economically and environmentally beneficial as they effectively reduce energy consumption and greenhouse gas emissions. In this study, energy saving wood composite was prepared by injecting a methyl methacrylate dispersion containing a mixture of VO2(M)@SiO2 core-shell nanocomposites and thermochromic microcapsules into wood templates. APTS was added to stabilize the suspension. The good compatibility between the injected substances and the wood template benefited from the PMMA and APTS that filled the cell lumen and bonded the substances, leading to energy saving wood composite with excellent dimensional stability, optical properties, and mechanical performance. More importantly, the energy saving wood composite exhibited outstanding temperature regulatory ability by shielding needless infrared radiation, resulting in thermal comfort. The unique properties of the energy saving wood composite could potentially be applied in building, furniture, thermal insulation, energy conversion, energy storage, and conservation.

Effect of H2O2 Bleaching Treatment on the Properties of Finished Transparent Wood.

Transparent wood samples were fabricated from an environmentally-friendly hydrogen peroxide (H2O2) bleached basswood (Tilia) template using polymer impregnation. The wood samples were bleached separately for 30, 60, 90, 120 and 150 min to evaluate the effects on the changes of the chemical composition and properties of finished transparent wood. Experimental results showed decreases in cellulose, hemicellulose, and lignin content with an increasing bleaching time and while decreasing each component to a unique extent. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) analysis indicated that the wood cell micro-structures were maintained during H2O2 bleaching treatment. This allowed for successful impregnation of polymer into the bleached wood template and strong transparent wood products. The transparent wood possessed a maximum optical transmittance up to 44% at 800 nm with 150 min bleaching time. Moreover, the transparent wood displayed a maximum tensile strength up to 165.1 ± 1.5 MPa with 90 min bleaching time. The elastic modulus (Er) and hardness (H) of the transparent wood samples were lowered along with the increase of H2O2 bleaching treatment time. In addition, the transparent wood with 30 min bleaching time exhibited the highest Er and H values of 20.4 GPa and 0.45 GPa, respectively. This findings may provide one way to choose optimum degrees of H2O2 bleaching treatment for transparent wood fabrication, to fit the physicochemical properties of finished transparent wood.

A TiO2/C catalyst having biomimetic channels and extremely low Pt loading for formaldehyde oxidation.

This study presents a TiO2/C hybrid material with biomimetic channels fabricated using a wood template. Repeated impregnations of pretreated wood chips in a Ti precursor were conducted, followed by calcination at 400–600 °C for 4 hours under a nitrogen atmosphere. The generated TiO2 nanocrystals were homogenously distributed inside a porous carbon framework. With an extremely low Pt catalyst loading (0.04–0.1 wt%), the obtained porous catalyst could effectively oxidize formaldehyde to CO2 and H2O even under room temperature (conv. ∼100%). Wood acted as both a structural template and reduction agent for Pt catalyst generation in sintering. Therefore, no post H2 reduction treatment for catalyst activation was required. The hierarchal channel structures, including 2–10 nm mesopores and 20 μm diameter channels, could be controlled by calcination temperature and atmosphere, which was confirmed by SEM and BET characterizations. Based on the abundant availability of wood templates and reduced cost for low Pt loading, this preparation method shows great potential for large-scale applications.

Inventory of Organic Carbon in a Pterogyne nitens Tul. Plantation in Southwest Bahia, Brazil

ABSTRACT Carbon binding capacity varies between forest plantations, mainly in terms of species and climate and soil conditions. The objective of this study was to estimate the amount of organic carbon stored in aerial tree biomass in the litter and soil of a homogeneous planting of Pterogyne nitens Tul. located in the Southwest Bahia region of Brazil. The woody biomass was obtained by destructive method. Litter collection was carried out using a wooden template (0.25 m2). Soil samples were collected at four depths (0-5, 5-10, 10-20 and 20-40 cm). The carbon stored in all studied compartments totaled 47.1 Mg ha-1 with a greater contribution from the ground (31.4 t ha-1). The accumulated litter was the lowest carbon compartment, storing about 1.4% of the total. Among the different fractions of the biomass, the stem is the largest carbon reservoir, representing about 46% of fixed C biomass.

Obtaining of biomorphic composites based on carbon materials

Abstract Aim of this paper is to present the properties of carbon preforms for the production of biomorphic composites. Carbon samples were obtained through pyrolysis of paulownia wood, replicating the microstructure of the cellulosic precursor. Many characterization methods such as Raman Spectroscopy, light microscopy, hardness tests and pore size analyzer detection were used to investigate the microstructure of the product as well as the pore size of carbon samples. Obtained results showed that the parts of early or late wood template play an important role in the pore size, specific surface area and pore volume of the product. This review aims to be a comprehensive description of the development of carbon chars: from wood templates and their microstructure to potential applications of biomorphic materials.

Development of Curvature Gap Estimation System for Deciding Thermal Forming Instructions of Ship Curved Shell Plates Using Laser Scanner

A thick steel plate with a unique curvature was employed to make the outer shell of a ship. This curved shell plate is shaped one at a time by craftsmen carrying out plastic deformation using gas heating. The process includes evaluation of forming accuracy and selection of thermal forming instructions. Both are done using fitting molds called “wooden templates” in a manner that is qualitative but dependent on individual skills. Thus, there is a problem of variation in quality. To solve the problem, research and development have been promoted on a manufacturing process assisted by a laser scanner that is a highly accurate three-dimensional measuring device. An evaluation method for forming accuracy has been established and has reached a satisfactory level for operation on site. However, the method of automatic selection of thermal forming instructions is still immature. Focusing on the curvature of frame lines on the outer plate that acts as an index when instructions for thermal forming are decided upon, a curvature gap estimation system was developed for outer plate frame lines using a laser scanner. Here, a frame line refers to the standard to be compared with a design shape to evaluate the forming accuracy of the members. The system extracts from measured data a point cloud that makes up each frame line, calculates curvature at a given point on the frame line, and visualizes it with a graph and a color map. This system uses an evaluation method whose curvature calculation has sufficiently appropriate accuracy and that is feasible and useful on site. First, the sufficiently appropriate accuracy of the curvature calculation was confirmed using a measurement form of a cylindrical model that simulated a gap between the distance direction generated by measurement with the laser scanner and the direction of laser irradiation. Next, the feasibility and usefulness on site were confirmed by applying the measurement method to the processing data of the ship shell outer plate shape that was obtained through the curving process in the shipyard, and then by comparing the record of regions thermally formed by the worker with index calculation results made by the system.

FUNGOS MICORRÍZICOS ARBUSCULARES E SERAPILHEIRA COMO INDICADORES DO EFEITO DE BORDA EM FRAGMENTO DE FLORESTA ESTACIONAL

As atividades humanas causadoras de desmatamentos favorecem a fragmentação e a formação de bordas na floresta, modificando as características bióticas e abióticas do ecossistema, o que pode ser avaliado através de indicadores do solo. Com isso, o objetivo deste estudo foi avaliar o estoque de serapilheira e a comunidade de fungos micorrízicos arbusculares (FMA) como indicadores do efeito de borda em um fragmento de Floresta Estacional em Vitória da Conquista, Bahia. Foram realizadas amostragens ao final de cada estação do ano. Para isso, foram delimitadas quatro faixas na direção borda-matriz (borda – 0-10 m, faixa 1 – 40-50 m, faixa 2 – 80-90 m e interior – 400 m). A serapilheira acumulada (quatro repetições por faixa) foi coletada com o auxílio de um gabarito de madeira (área 0,25 m2). Nos mesmos pontos em que se coletou a serapilheira foram coletadas amostras de solo (camada 0-5 cm) para extração dos esporos de fungos micorrízicos. O efeito de borda em fragmentos de Floresta Estacional Semidecidual pode alterar o estoque de serapilheira com redução de massa nos locais mais próximos da borda. A comunidade de fungos micorrízicos arbusculares apresentou a ocorrência de espécies exclusivas em determinadas faixas no gradiente borda-interior do fragmento.

Wood Nanotechnology for Strong, Mesoporous, and Hydrophobic Biocomposites for Selective Separation of Oil/Water Mixtures.

Tremendous efforts have been dedicated to developing effective and eco-friendly approaches for separation of oil-water mixtures. Challenges remain in terms of complex processing, high material cost, low efficiency, and scale-up problems. Inspired by the tubular porosity and hierarchical organization of wood, a strong, mesoporous, and hydrophobic three-dimensional wood structure is created for selective oil/water separation. A delignified wood template with hydrophilic characteristics is obtained by removal of lignin. The delignified wood template is further functionalized by a reactive epoxy-amine system. This wood/epoxy biocomposite reveals hydrophobic/oleophilic functionality and shows oil absorption as high as 15 g/g. The wood/epoxy biocomposite has a compression yield strength and modulus up to 18 and 263 MPa, respectively, at a solid volume fraction of only 12%. This is more than 20 times that of cellulose-based foams/aerogels reconstructed from cellulose nanofibrils. The favorable performance is ascribed to the natural hierarchical honeycomb structure of wood. Oil can be selectively absorbed not only from below but also from above the water surface. High oil/water absorption capacity of both types of wood structures (delignified template and polymer-modified biocomposite) allows for applications in oil/water separation.

Lignin-Retaining Transparent Wood.

Optically transparent wood, combining optical and mechanical performance, is an emerging new material for light‐transmitting structures in buildings with the aim of reducing energy consumption. One of the main obstacles for transparent wood fabrication is delignification, where around 30 wt % of wood tissue is removed to reduce light absorption and refractive index mismatch. This step is time consuming and not environmentally benign. Moreover, lignin removal weakens the wood structure, limiting the fabrication of large structures. A green and industrially feasible method has now been developed to prepare transparent wood. Up to 80 wt % of lignin is preserved, leading to a stronger wood template compared to the delignified alternative. After polymer infiltration, a high‐lignin‐content transparent wood with transmittance of 83 %, haze of 75 %, thermal conductivity of 0.23 W mK−1, and work‐tofracture of 1.2 MJ m−3 (a magnitude higher than glass) was obtained. This transparent wood preparation method is efficient and applicable to various wood species. The transparent wood obtained shows potential for application in energy‐saving buildings.

Biomorphic ceramics from wood-derived precursors

ABSTRACTMaterials development is driven by microstructural complexity and, in many cases, inspired by biological systems such as bones, shells and wood. In one approach, one selects the main microstructural features responsible for improved properties and design processes to obtain materials with such microstructures (continuous-fibre-reinforced ceramics, porous ceramics, fibrous ceramic monoliths, etc.). In a different approach, it is possible to use natural materials directly as microstructural templates. Biomorphic ceramics are produced from natural and renewable resources (wood or wood-derived products). A wide variety of SiC-based ceramics can be fabricated by infiltration of silicon or silicon alloys into cellulose-derived carbonaceous templates, providing a low-cost route to advanced ceramic materials with near-net shape potential and amenable to rapid prototyping. These materials have tailorable microstructure and properties, and behave like ceramic materials manufactured by advanced ceramic processing approaches. This review aims to be a comprehensive description of the development of bioSiC ceramics: from wood templates and their microstructure to potential applications of bioSiC materials.

Luminescent and Transparent Wood Composites Fabricated by Poly(methyl methacrylate) and γ-Fe2O3@YVO4:Eu3+ Nanoparticle Impregnation

Natural wood is functionalized using the index matching poly(methyl methacrylate) (PMMA) and luminescent γ-Fe2O3@YVO4:Eu3+ nanoparticles to form a novel type of luminescent and transparent wood composite. First, the delignified wood template was obtained from natural wood through a lignin removal process, which can be used as a support for transparent polymer and phosphor nanoparticles. Then, the functionalization occurs in the lumen of wood, which benefits from PMMA that fills the cell lumen and enhances cellulose nanofiber interaction, leading to wood composites with excellent thermal properties, dimensional stability, and mechanical properties. More importantly, this wood composite displays a high optical transmittance in a broad wavelength range between 350 and 800 nm, magnetic responsiveness, and brightly colored photoluminescence under UV excitation at 254 nm. The unique properties and green nature of the luminescent wood composite have great potential in applications including green LED lighting eq...

Adsorption Characteristics of Copper in Water by the Porous Biomorph-Genetic Composite of HAP/C with Eucalyptus Wood Template

The specific characteristics and mechanism of adsorption of Cu(Ⅱ) were studied by using HAP/C composite (PBGC-HAP/C) as adsorbent, and using pH value of the solution system, initial concentration of Cu(Ⅱ) and particle size of the material as influential factors. The results showed that when the solution was weak acid (pH=5), the adsorption effect was the best; the increase of the initial concentration of the reaction system was not conducive to the enhancement of the adsorption effect; and the decrease of the particle size of the adsorbent facilitated the adsorption process. The pseudo-second-order kinetic model could accurately describe the adsorption process, and the calculated adsorption capacity(0.99, 1.93, 4.03 mg·g-1)was close to the experimental measured values(0.99, 1.93, 4.05mg·g-1); Langmuir model could fit the adsorption process very well, which indicated that adsorption was monolayer adsorption and the increase of temperature was conducive to adsorption. The thermodynamics test results of ΔGθ<0, ΔSθ>0 and ΔHθ>0 showed that the adsorption process was endothermic and spontaneous. Through comparative analysis of the SEM, EDS, XRD and FTIR of materials before and after adsorption, the results indicated that the chemical complexation reaction of Cu(Ⅱ) with the oxygen functional groups on the surface of PBGC-HAP/C was the main purification mechanism, which was accompanied with physical adsorption, electrostatic adsorption and ion exchange.

Forming Information Calculation Algorithm of 3-D Template for Evaluation of Curved Hull Plates

Curved hull plates are essential to the construction of a ship. Moreover, curved hull evaluation is significant during the curved hull plate forming process. Most shipyards use 2D- and 3D-type wooden template to estimate curvature of plates by placing the template on specific positions of curved hull plates. Only the 3-D template can be utilized to evaluate plates that are relatively thick with large radius of curvature. In general, forming plans of the 3-D template, based on the given information, are drawn manually by workers, and the information is only given for plates that may require 3-D templates. These plates are predicted empirically by the designers in the detailed design phase, resulting in the presence of unpredicted plates. For unpredicted plates, workers used to request additional information for manufacturing, and during the process, there exists a complex information exchange between related departments, which is a time-consuming process. To solve the above-mentioned problems, in this paper, a 3-D template forming information calculation algorithm, based on the surface geometric information, was proposed. Moreover, the proposed algorithm was implemented as a computer program in which forming information of 3-D template can be calculated automatically.

Transparent magnetic wood composites based on immobilizing Fe3O4 nanoparticles into a delignified wood template

Wood is one of the key renewable resources due to its excellent structure and physical properties. Functionalized wood and wood-based materials not only possess important engineering applications but also great potential in some new technology fields, such as electronics, optics, and energy. Endowing these functional wood-based materials with magnetic properties has an important significance for exploring lightweight building materials or electronic devices. In this study, we report the fabrication of a transparent magnetic wood (TMW) based on filling the index-matching methyl methacrylate and magnetic Fe3O4 nanoparticles into the delignified wood template. The presence of the polymer and Fe3O4 nanoparticles within the wood structure is monitored by scanning electron microscopy, energy-dispersive X-ray analysis, and Fourier transformation infrared spectroscopy. The resulting TMW possesses moderate transparency and magnetic properties combining with outstanding mechanical performance. Moreover, the influence of the concentration of Fe3O4 nanoparticles on the final optical, magnetic, and mechanical properties of TMW is also discussed. This work provides a potential strategy to develop wood-based materials for magneto-optical application.

Preparation of biomorphic porous zinc oxide by wood template method

This paper presents an effective method to fabricate highly porous zinc oxide (ZnO) derived from different wood templates, where the microstructure features of wood template were well reproduced in the final product. Biomorphic ZnO was fabricated via the sol–gel method by the infiltration of the precursor sol into the wood template and the sintering of wood template at high temperature under air atmosphere. Many characterization methods such as x-ray diffraction (XRD), scanning electron microscopy (SEM) and pore size analyzer detection were used to investigate the crystalline phase and microstructure of the product as well as the pore size of biomorphic ZnO. In our work, highly porous ZnO derived from different wood templates had been prepared. The relevant results revealed that the specie of wood template and sintering temperature played vital roles in the pore size, specific surface area and pore volume of the product.

Optically Transparent Wood from a Nanoporous Cellulosic Template: Combining Functional and Structural Performance.

Optically transparent wood (TW) with transmittance as high as 85% and haze of 71% was obtained using a delignified nanoporous wood template. The template was prepared by removing the light-absorbing lignin component, creating nanoporosity in the wood cell wall. Transparent wood was prepared by successful impregnation of lumen and the nanoscale cellulose fiber network in the cell wall with refractive-index-matched prepolymerized methyl methacrylate (MMA). During the process, the hierarchical wood structure was preserved. Optical properties of TW are tunable by changing the cellulose volume fraction. The synergy between wood and PMMA was observed for mechanical properties. Lightweight and strong transparent wood is a potential candidate for lightweight low-cost, light-transmitting buildings and transparent solar cell windows.

Preparation of mechanical abrasion and corrosion resistant bulk highly hydrophobic material based on 3-D wood template

BH-wood had low free energy microstructures extending throughout the whole volume, and possessed excellent mechanical abrasion and corrosion resistance.