Thứ Năm, 1 tháng 3, 2012

The convenience of Wood

Wood is a material offers good features.

Cross section of a European tree widget bar (Taxus baccata).

Wood is a form of physical existence is made up primarily of basic components such as cellulose (40-50%), hemicellulose (15-25%), lignin (15-30%) and some other substances. It is exploited mainly from woody species.
Table of Contents
• 1 The use of wood
• 2 Advantages and disadvantages of wood and how to fix
o 2.1 Advantages of Wood
o 2.2 Cons and remedial measures
• 3 wood section
• 4 Wood early, late wood
• 5 Wood sense, wood core
• 6-year cycle
• 7 coniferous wood
• 8 Wood broadleaf
• 9 References

The use of wood
§ Preliminary statistics in the world today has over 100 branches of wood used as raw materials with over 22,000 different jobs and produce more than 20,000 types of products.
§ Wood is the raw materials used by man long and wide, is one of the main materials of the national economy.
§ In the official document to date, the government of Vietnam still ranked third leading timber as electricity and coal.
§ Wood is widely used in industry, agriculture, transportation, architecture, construction and mining.
§ The wood is also used as stationery, musical instruments, sports equipment, play train, truck, boats, ferries, bridges, furniture and appliances student, household appliances, and specialized work such as hospitals, libraries ...
Advantages and disadvantages of wood and how to fix
Advantages of Wood
§ Insulation, insulation, prevent moisture, thermal expansion baby.
§ Applications should be able to use the machines and tools for sawing, cutting, planing, drilling, split split with high speed.
§ Easy reassembling by nails, dream, glue.
§ There is still grain is nice and colored, easy jewelry surface.
§ Easy to use chemical separation paper and rayon.
§ As a natural material, just planting, care and use simple machines to mining and processing is going to be.
Cons and remedial measures


Damage wood by wood pests
§ slow growth, the diameter is limited, there are many natural defects. Use technical measures to forestry - born in the work of reasonable care and planting forests.
§ Ease of entry, susceptible organisms (termites, ...) sabotage. Need spray impregnated with anti-termite chemicals.
§ low elasticity. Need modified wood by means of pressure or chemical dipping.
§ While drying are easily cracked, warped, transformed. Need plans for sawing, slicing appropriate.
§ In the body usually extracts, often making it difficult for jewelry work surfaces, or corrosion of the cutting tool.
§ The rate of high elasticity, the product most often affected by humidity, ambient temperature. Need to remove the factors causing this stretch:
§ impregnated chemicals to replace the original (-OH) in the wood
§ Dry wood to remove free water and seepage from the timber. Drying at 103 ± 2 ° C temperature
§ Easy to catch fire, flammable. Need impregnated or coated anti-ignited the
Wood section
In this study the texture of wood is often cut 3mat research on typical:
§ Cross: The cross section is perpendicular to the longitudinal axis trunk.
§ radial cross section: A cross-sectional study with longitudinal axis parallel to the trunk and through the center (core) trunk.
§ tangential section: section parallel to the wood along the trunk axis and one perpendicular to the radial line.
Early wood, late wood
§ Wood soon as the wood produced in a cycle of growth in favorable growth conditions (in Vietnam is usually lower spring). Wood often be lighter soon. The cells are usually thin-walled early wood, large intestine. Resistant to mechanical stresses are lower.
§ Wood Wood is a born late in the growth cycle of trees in growth conditions are not favorable (in Vietnam usually fall and winter). Usually dark-colored late wood. Thick-walled late wood cells, small intestine, resistant to mechanical impact possible.
Sensory Wood, wood core

Sensory Wood, wood core
Wood core is formed by the visual timber. This is a biotransformation process, physics and chemistry is very complex. First of all dead cells, can-bit form, the organic matter appears: resins, pigments, tannins, essential oils, ... In intestinal cells the cell wall stain on wood core makes dark, heavy, hard, hard waterproof, and resistant worms, fungi, termites than wood feeling.
On cross-wood core has a dark color sense than wood. In some species, typical of the phenomenon being hollow core wood. There is no relationship between growth and stem diameter sensory wood volume, wood core. Species do not form the core wood, wood species very early core formation, makes sense the thickness of very thin wood (eg wood them to, they Mulberry).
Year round
As the cambium rings distributed by birth usually is 1 year (depending on geographic location, for example in Vietnam, the growth cycle coincides with a year). The width of five reflects a growth rate of trees. Number five tells us that old tree. On cross section, are five concentric circles, on the section they are radial straight lines parallel to each other and can be parallel to the longitudinal axis trunk.Depending on the biology of the species and characteristics of weather conditions year round nutrient that can be easily seen or hard to recognize.
Coniferous wood

Wood is used as a high-end crafts Units in domestic market
Coniferous wood is natural wood products harvested from the conifers. Coniferous wood structure is simple, the composition consists mainly coquan cell cycle, cell vertical management, wood rays, soft tissue that lines the trunk, plastic pipes.
Chemical composition of coniferous wood consisting mainly of cellulose accounts for 43-52%, 15-20% hemixellulo, accounting for 23-34% lignhin, in addition to a number of other additives such as colorants, essential oils, .. . very small proportion.
A common characteristic of coniferous wood is five clear, late wood wood soon distinction. Small wood beams and less. Grain straight, rarely inclined fibers.
Broadleaf Timber
Broadleaf wood is natural wood products harvested from broadleaf plants.Broadleaf timber has a structure more complex coniferous wood, the major constituents: timber vessels, soft tissue that lines the trunk, wood beams, wood fibers, managing vertical cells, resin ducts, formed class .
Chemical composition of broad-leaved wood including cellulose accounts for 41-49%, 20-30% hemixellulo accounting, accounting for 16-25% lignhin, in addition to the presence of some extracts. Component elements is about to slag each other, coniferous wood similar regardless of the species: C 49-50%, 43-44% O; H ≈ 6%, N ≈ 1%.

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