Wood is produced from the plants of gymnosperms and angiosperms and is rich in biodiversity. Tree growth is a complex and co-scientific biochemical process that uses light energy to develop itself into a large organism using carbon dioxide, water and minerals. Wood is the main product of vegetative growth of trees. The formation of wood is a process of absorbing carbon dioxide, carbon sequestration and releasing oxygen, which is conducive to improving the ecological environment. Pet Toys,Pet Chew Toy,Custom Pet Dog Toy,Pet Dog Chew Toy Yangzhou Pet's Products CO.,LTD , https://www.yzpqpets.com
Wood, as a traditional material, has been used by humans. With the changes in natural resources and human needs and the advancement of science and technology, the use of wood from primitive logs to the use of sawn timber, veneer, shavings, fibers and chemical components has formed a large family of new wood materials. Such as cavity plywood, particle board, fiberboard, veneer lumber, laminated timber, reconstituted wood, oriented strand board, reconstituted decorative wood and other wooden reconstituted materials, as well as gypsum particle board, cement particle board, wood / plastic composite, wood / metal composite, Wood-based composite materials such as wood conductive materials and wood ceramics.
Wood materials play a huge role in the fields of construction, furniture, packaging, and railways. Today, as non-renewable resources are depleted and human society is moving towards sustainable development, wood is characterized by its unique carbon sequestration, renewable, natural degradation, aesthetics and degraded indoor environment, as well as high strength-to-weight ratio and processing. The processing and utilization characteristics such as low energy consumption will make a significant contribution to the sustainable development of society. Compared with other materials, wood has unique properties such as porosity, anisotropy, swelling and shrinkage, flammability and biodegradability. How to better utilize these characteristics and minimize its side effects is a timber scientist and The main problems that engineering and technical experts have worked hard to solve. In recent years, forest scientists have also actively participated in wood science research, understanding and improving the basic characteristics of wood from the genetic perspective of trees.
- Research status of wood materials
The research and development of wood materials is closely related to the development of resources, economy and environment. Wood science, wood chemical processing, advanced manufacturing technology of wood products, wood-based composite materials, wood composite materials, wood ecological environment materials and wood structure engineering The field is more active.
Wood science
Wood science is mainly to study the technical problems of tree growth by biological theory, focusing on the relationship between wood material, material properties and biological formation and processing. On the basis of improving the speed of wood formation, we focus on genetic modification techniques such as molecular genetic markers, lignin gene transfer, lignin forming gene isolation and cloning, gene localization of wood, and quantitative genetics of wood fiber molecules to improve the basic properties of wood. Genetic stability; study the effects of tree growth conditions, initial planting density, fertilization, thinning, pruning and other tree growth conditions on wood properties and quality; study the formation and release of wood growth stress; and research and development of standing timber staining and square trees Cultivation techniques.
As wood resources change from natural forests to plantations, bamboo, rattan and other grass and herb resources have become an important supplement to timber resources. Therefore, advanced scientific theories and methods must be used to study wood in depth. Microstructure, composition and its relationship to performance lay the scientific foundation for the development of new biological materials. The key research areas are: comparative biology, comparative anatomy, comparative physics, comparative chemistry and comparative mechanics of mature wood of plantation wood and natural forest wood; basic characteristics of plant materials and ultrastructure of cell rafts Relationship; distribution and regulation of various enzymes related to the formation and decomposition of algae, fungal cell walls; quantification of wood plant tissue characteristics; antibacterial, insect-resistant, anti-cancer, aroma of wood bioactive substances, for animals The physiological and pharmacological effects, the coagulation and retardation of inorganic mineral materials, and biodegradability. For example, the thermo-imaging method is used to study the relationship between stress-strain distribution, water-strain and wood material uniformity; the mechanism of wood fluid flow is studied by nonlinear theory; the soft wood is hardened by roll/water pressure and heat setting technology. Stereotype processing; classify wood with computer vision technology, detect wood surface quality and defects; develop non-destructive testing technology to improve the safety of wood with high variability; use x-ray imaging method to detect wood pest damage and insect control effect; The dynamic method is used to detect the elastic mechanical properties of wood; the infrared detection method is used to monitor the stability of urban ancient trees.
2. Wood chemical processing
The study of wood chemical treatment methods places special emphasis on safety and economy, taking into account toxicity, potency, solubility and suitability, extending from pre-treatment of wood to pre-treatment and post-use repair. The key research areas are: the fixation of non-toxic anti-borrowing boron preparations, the development of water-based insecticides and fungicides (pastes, emulsions, boron rods, steam, etc.) for the rapid penetration of low organic volatiles; Wood coatings; refining and synthesizing wood natural preservatives; introducing bio-protection technology to study the inhibition of wood symbiotic bacteria on wood rot fungi; wood fireproof materials expand from difficult to non-combustible.
Wood chemical utilization technology extends to gasification, liquefaction, plasticization, chemical modification, bleaching, dyeing, and the use of wood components and the use of non-wood plant materials. Focus on the relationship between the structure and physical properties of plant polymers; the role of enzymes in the conversion of plant materials; cellulose and lignin are carbohydrates, and the macromolecules are cleaved into small molecules that can be degraded by human enzymes. It is possible to develop new ones. Woody feed; after alkali extraction and acid neutralization of lignin, lignin carbon fiber can be obtained (Fig. 1); wood can be liquefied with strong acid, phenol or polyhydrocarbyl alcohol, and waste wood can be fully utilized. It can be used as a multi-mercapto compound to directly prepare new biodegradable foam materials and phenolic resins, partially replacing petroleum products, and has the advantage of being biodegradable.
3. Advanced manufacturing technology for wood products
Based on traditional wood machining, the advanced manufacturing technology of wood products continuously absorbs the achievements in the fields of machinery, electronics, information and modern management technology, and extends the discipline to the design, manufacture, production, testing, management and service of wood products. Throughout the process, advanced manufacturing technologies such as robotics, computer-aided design, computer-aided manufacturing, computer numerical control machining centers, agile manufacturing technologies, and flexible production technologies are widely used. Based on the computer-supported simulation technology, the whole process of designing, processing and assembling wood products is uniformly modeled. In the product design stage, real-time, parallel simulation of the entire manufacturing process and its impact on product design, predicting product performance, product production technology, product manufacturability, thus more effective, more economical, flexible and flexible Organize production to make the design and layout of the factory and workshop more reasonable and effective, in order to achieve product development cycle and cost minimization, product design quality optimization and production efficiency. The flexible production technology of wood products using computer numerical control technology, robot technology and logic process control technology can change the design style within 60 minutes, and can introduce new products within 6 days, satisfying the diversified market and personalized consumption for small batches and multi-variety products. The need to play is of great significance.
4. Wood-based composite materials
Wood is a natural material and its range of use is limited by its physical and mechanical properties. Wood components such as wood, wood, veneer, shavings or fiber are combined with organic polymers, inorganic non-metals or metal reinforcements or functional bodies to form wood-based composite materials, including wood/rubber laminated flooring and wood veneers. /Glass fiber/aluminum ternary composite material, gypsum particle board, cement particle board, wood fiber/synthetic fiber bird material, injection molding wood powder/plastic composite material (Fig. 2), wood conductive material and wood ceramics. These wood-based composites have new physical and mechanical properties not found in the original wood thorns (æ²gi.w..d). Current research focuses on the relationship between composition, structure, process, properties and behavior of wood-based composites and interface properties, and material design and manufacturing in accordance with the performance requirements of the end use of the product.
Research and development of wood-plastic composite materials, such as synthetic polymers/wood flour (wood fiber, wood shavings, wood veneers) and other composite materials, aims to reduce costs, increase flexibility and recyclability, processability, flexible design and improvement strength. The research fields include: the damping characteristics of wood/polymer composites and the influence of phase solvents and coupling agents on the secondary mechanical properties of composites; the use of supercritical fluid treatment technology and plasma treatment technology to improve the wood/plastic interface reaction performance; Reverse gas chromatography was used to study the basic physicochemical parameters controlling the interface structure and properties of wood fiber/polymer composites. The ultraviolet light, the 60-ray source, the x-ray and the y-ray were used to crosslink the polymer monomer with the wood. Reaction, study the composite manufacturing theory and performance evaluation of wood and other materials.
Another frontier in the research of wood-based composites is the functionalization of wood materials, which can be roughly divided into filling, mixing, compounding and surface covering methods, such as filling conductive wood into wood, conductive short fibers and wood fibers or Wood flour is mixed and compounded. The conductive fiber and the wood fiber can also be mixed into a functional paper so that the entire surface, the outer surface or the inner portion of the paper becomes a continuous selective conductive material. After the small wood piece is nickel-plated and molded, it can be made into a curved selective conductive material, and the electromagnetic wave shielding effect can reach 40~70dB (for example, the shielding efficiency of the electromagnetic wave is 20dB for the frequency of 1.5GH, and the electromagnetic wave interference or pollution intensity can be attenuated by 90%. ), the volume resistivity can reach 0.15-5.9Q.cm (solid wood is generally on the order of 108~1011). Research and development of wood-shielded functional composites to reduce indoor electromagnetic pollution in the range of 9 kHz to 1.5 GHz, which is conducive to achieving environmental certification (such as ISO14000) and safety certification (such as CE marking), adding added value of wood board products, indoors There are broad prospects for applications such as decoration, office furniture, and public soup.
Wood ceramics are porous carbon materials obtained by sintering a composite material made of a wood material and a thermosetting resin under high temperature and anaerobic conditions, and have a new function. The sintering temperature and temperature rise rate of wood ceramics are related to their mechanical properties. The static bending strength of wood ceramic materials reaches 27 MPa (wood is 29~183Mpa), and the elastic modulus reaches 7.5Gpa (wood 4~21GPa). Wood ceramic materials transition from insulator to conductor with the increase of alkylation temperature, the specific gravity is 0.7~1.0 (wood is 0.24~1.13), which can replace the traditional ferrite electromagnetic shielding material, and can also be used as far infrared heating material and absorption. The material (radiation energy of 4.0~22.0um is 80% of black body), can also be used as non-lubricating sliding parts (capacity coefficient is 0.1~0.15, Brinell hardness can reach 60MPa), and it is easy to process and manufacture, high strength and excellent Capacitance and wear characteristics, as well as self-contained lubricants, corrosion resistance and low density (1/9~1/13 for steel).