Wood is a porous and fibrous structural network found in stems and roots of trees and other woody plants. It is an organic material, a natural composite of strong cellulosic fibers in tension and embedded in a compression-resistant lignin matrix. Wood is sometimes defined only as a secondary xylem in a tree trunk, or more broadly defined to include the same type of tissue elsewhere as in the roots of trees or bushes. In a live tree he performs a support function, allowing woody plants to grow large or stand alone. It also conveys water and nutrients between leaves, other growing tissues, and roots. Wood can also refer to other plant materials with comparable properties, and to wood-engineered material, or wood or fiber chips.
Wood has been used for thousands of years for fuel, as a construction material, for making tools and weapons, furniture and paper, and as a raw material for the production of pure cellulose and its derivatives, such as cellophane and cellulose acetate.
In 2005, the growth of forest stocks worldwide was around 434 billion cubic meters, 47% of which were commercial. As an abundant source of carbon-neutral renewable resources, wood materials have attracted attention as a source of renewable energy. In 1991 about 3.5 billion cubic meters of timber was harvested. Dominant use is for furniture and building construction.
Video Wood
History
The discovery of 2011 in the province of New Brunswick in Canada produced the earliest known crop to plant timber, about 395 to 400 million years ago.
Wood can be dated by carbon dating and in some species by dendrochronology to determine when a wooden object is made.
People have been using wood for thousands of years for various purposes, including as fuel or as construction materials to house, equipment, weapons, furniture, packaging, artwork, and paper. The construction is known to use wood dated ten thousand years. Buildings like Neolithic European long houses made of wood.
Recent wood usage has been enhanced with the addition of steel and bronze into the construction.
Year-to-year variations in the width of tree circles and the abundance of the isotopes provide clues to the prevailing climate at the time the tree is cut.
Maps Wood
Physical properties
Growth ring
Wood, in a narrow sense, is produced by trees, which increases the diameter by the formation, between the existing wood and the inner shell, the new wooden layer enveloping all the stems, branches, and roots. This process is known as secondary growth; it is the result of cell division in the vascular cambium, lateral meristem, and subsequent new cell expansion. These cells then proceed to form thickened secondary wall cells, mainly composed of cellulose, hemicellulose and lignin.
Where are the differences between the four different seasons, e.g. New Zealand, growth can occur in different annual or seasonal patterns, leading to growth rings; this can usually be seen most clearly at the end of the log, but also seen on other surfaces. If the uniqueness between seasons is annual (as in the equator, for example Singapore), this growth ring is referred to as the annual ring. Where there is little difference the growth of a seasonal ring may be unclear or absent. If the bark of a tree has been removed in a particular area, the rings will probably change shape as the plant grows too large.
If there is a difference in the growth ring, then the part of the growth ring that is closest to the center of the tree, and formed early in the growing season when growth is fast, usually composed of wider elements. They are usually lighter than those near the outside of the ring, and are known as earlywood or springwood. The exterior that formed later in this season became known as latewood or summerwood. However, there is a big difference, depending on the type of wood (see below).
Knots
As the trees grow, the lower branches often die, and their base can become too high and covered by the next log layer, forming a type of imperfection known as a knot. The dead branch may not be attached to the logs except at the base, and may break after the tree has been sawn as a board. Knots affect the technical nature of wood, typically reducing local forces and increasing the tendency to split along the wood grain, but can be exploited for visual effects. In a longitudinal sawing board, a knot will appear as a "regular" (usually darker) rough piece of wood in which the remaining grain of wood "flows" (part and rejoins). In one node, the direction of wood (grain direction) to 90 degrees differs from ordinary grain direction.
In the tree, the node is the base of the side branch or the inactive bud. A knot (at the base of the side branch) is conical (harsh coarse cross section) with the inner end at the point of the trunk diameter at which the vascular cambium of the plant is located when the branch is formed as a bud.
In assessing wood and structural wood, the knots are classified according to their shape, size, level of health, and constancy. This firmness is influenced by, among other factors, the length of time for the branch to die while the stick is attached to grow.
Knot material affects crack and warping, ease of work, and wood cleavability. They are defects that weaken the wood and lower its value for structural purposes where strength is an important consideration. The weakening effect is much more serious when the wood is subjected to a force perpendicular to the grain and/or voltage than when under load along the grain and/or compression. The extent to which the knots affect the strength of the light depends on position, size, amount, and condition. A node on the top is compressed, while the one on the underside is tense. If there is a season check on the node, as is often the case, it will offer little resistance to this tensile stress. Small knots, however, can be placed along the neutral plane of the beam and increase the power by preventing longitudinal shear. Knots on boards or boards are least harmful when they stretch their wings to the widest corner. Knots that occur near the end of the beam do not weaken it. The sound knot that occurs in the center of a quarter-high ray from both sides is not seriously flawed.
Nodes do not always affect the stiffness of structural wood, this will depend on the size and location. Stiffness and elastic strength are more dependent on sound wood than on local defects. Breaking strength is particularly vulnerable to defects. The knot sound does not weaken the wood when it is subject to compression parallel to the grain.
In some decorative applications, wood with knots may be desirable to add visual interest. In applications where wood is painted, such as skirting boards, fascia boards, door frames and furniture, the resin in wood can continue to 'bleed' up to the surface of the knot for months or even years after manufacture and displayed as yellow or brownish stains Paint or primer knots (knotting), properly applied during preparation, may reduce this problem but are difficult to control completely, especially when using mass-produced timber stocks.
Heartwood and sapwood
Heartwood (or duramen) are woods that as a result of natural chemical transformations have become more resistant to decay. The formation of tubes is a genetically programmed process that occurs spontaneously. Some uncertainty exists as to whether wood dies during pith formation, because it can still react chemically to decaying organisms, but only once.
Heartwoods are often visually different from life's pigs, and can be distinguished in transverse sections where the boundaries will tend to follow the growth ring. For example, sometimes darker. However, other processes such as spoilage or insect invasion can also blacken wood, even in woody plants that do not form pith, which can cause confusion.
Sapwood (or alburnum) is the younger, the outer wood; in the growing tree it is living wood, and its main function is to drain water from the roots to the leaves and store and reward according to the reserve season prepared in the leaves. However, by the time they become competent to do water, all tracheids and xylem vessels have lost their cytoplasm and the cells are functionally dead. All the wood in the tree was first formed as sapwood. The more tree leaves and the stronger the growth, the greater the volume of pig needed. Therefore, trees that grow rapidly in the open have thicker sapwood for their size than trees of the same species that grow in dense forest. Sometimes trees (from pig-shaped species) that grow in the open can be large enough, 30 cm (12 inches) or more in diameter, before any log begins to form, for example, on a second-growth hickory, or open-grow pine.
The term pith is derived only from its position and not of great importance to the tree. This is evidenced by the fact that trees can thrive with a truly decaying heart. Some species begin to form wooden cores early in life, so only have a thin layer of pigs life, while in others the changes take place slowly. Thin sapwood is characteristic of species such as chestnut, black locust, mulberry, osage-orange, and sassafras, while in maple, ash, hickory, hackberry, beech, and pine, thick sapwood is the rule. Other people never form the pith.
There is no definite relationship between the annual growth ring and the amount of pig. In the same species, the cross-sectional area of ​​the cork is very proportional to the crown size of the tree. If the ring is narrow, more than is needed than the width. As the tree grows larger, the sap should always be thinner or materially increase in volume. Sapwood is relatively thicker at the top of tree trunks than near the base, because the age and upper diameter are less.
When a very young tree is covered with limbs almost, if not completely, to the ground, but as it grows older some or all of them will eventually die and break or fall. The subsequent growth of the wood can completely conceal the stub which will anyway remain as a knot. No matter how smooth and clear a note is outside, it's closer in the middle. As a result, the sapwood of an old tree, and especially a forest tree, will be freer from the knot than the inner pith. Since most wood uses, knots are defects that weaken wood and interfere with the ease of work and other properties, the gaharu piece of wood given, because of its position in the tree, may be stronger than a piece of wood. pith of the same tree.
It is remarkable that the inner core of the old trees remains as healthy as ever, because in many cases it is hundreds, and in some instances, thousands of years. Any broken branches or roots, or deep wounds of fire, insects, or falling wood, can cause the entrance to decay, which, once started, can penetrate through the tree trunk. Larvae of many insects burying the trees and their tunnels remain unlimited as a source of weakness. Whatever the advantage, however, that sapwood may be in this connection is due to its age and relative position.
If a tree grows throughout its life in the open and the soil and location conditions remain unchanged, it will make its fastest growth in youth, and gradually decline. The annual growth rings for years are wide enough, but then they become narrower and narrower. Since each ring is successfully placed on the outside of the previously formed wood, if the tree materially increases wood production year by year, the ring should always be thinner because the trunk becomes wider. As the tree reaches maturity, its crown becomes more open and annual timber production diminishes, thereby reducing more wide-circle growth. In the case of trees that grow in the forest so much depends on the competition of the trees in their struggle to get light and food, the periods of rapid and slow growth can alternate. Some trees, like the southern oak tree, retain the same ring width for hundreds of years. However, overall, when a tree is larger in diameter, the width of the growth ring decreases.
Different pieces of wood from large trees may differ with certainty, especially if the tree is large and mature. In some trees, the wood that is placed at the end of the tree life is softer, lighter, weaker, and even more textured than previously produced, but in other trees, the opposite is true. This may or may not fit the pith and pig. In large logs, sapwood, because of time in the life of trees when planted, may be lower in hardness, strength, and toughness for woods that are equally heard from the same wood. In smaller trees, the opposite may be true.
Color
In species showing a clear distinction between the wooden terraces and the natural wood-colored sapwoods are usually darker than sapwood, and very often the contrast is striking (see section of yew log above). This is produced by deposits in the wood core from chemical substances, so dramatic color variations do not imply significant differences in the mechanical properties of wood and ironwood, although there may be significant biochemical differences between the two.
Some experiments on very longleaf pine resin specimens show an increase in strength, because the resin increases the strength when dry. This saturated pith of resin is called a "fat lighter". The structure built from fat lighter is almost resistant to decay and termites; But they are very flammable. Old longleaf pine stumps are often dug, broken into small pieces and sold as firewood for fires. Stubbed stumps may actually still be a century or more since they were cut. Firs infused with coarse and dry resins also greatly increase in strength.
Since the latewood growth rings are usually darker than the early wood, this fact can be used in assessing visually density, and therefore the hardness and strength of the material. This is particularly the case with conifer-type forests. In porous wood, early wooden vessels often appear on completed surfaces as darker than denser latewood, although on cross-sections of pith wood, the reverse is generally true. Otherwise, the color of wood is not an indication of strength.
Abnormal wood color changes often indicate a diseased condition, indicating an imbalance. Black checks in western hemlock are the result of insect attacks. The reddish-brown lines are so common in hickory wood and certain others are mostly due to injuries by birds. The color change is only an indication of injury, and most likely does not itself affect the properties of the wood. Certain fungus-producing fungi give the distinctive colors of wood which then become a symptom of weakness; However the interesting effect known as spalting produced by this process is often regarded as a desirable characteristic. The usual sap staining is due to the growth of the fungus, but it does not always produce a weakening effect.
Water content
Water occurs in wood live in three locations, namely:
- on the cell wall,
- in the cell's protoplasmic content
- as free water in the cavity and cell space, especially xylem
Inside the wooden core it occurs only in the first and last form. The dried wood thoroughly holds 8-16% of water in the cell wall, and is absent, or practically non-existent, in other forms. Even dried dried wood has a small percentage of moisture, but for all but the chemical purposes, it can be considered completely dry.
The general effect of the water content on the wood substance is to make it softer and more flexible. The same effect occurs in the softening action of water on raw skin, paper, or cloth. To some extent, the greater the water content, the greater the softening effect.
Drying produces a definite increase in the strength of wood, especially in small specimens. An extreme example is the case of a completely dry cypress block 5 cm in part, which will sustain a permanent load four times larger than a green (unplugged) block of the same size.
The greatest increase in strength due to drying is the final crushing force, and strength at the elastic limit in endwise compression; this is followed by a breaking modulus, and pressure on the elastic limit in cross-bending, while the modulus of elasticity is least affected.
Structure
Wood is a heterogeneous material, hygroscopic, cellular and anisotropic. It consists of cells, and the cell wall consists of micro-cellulose from cellulose (40% - 50%) and hemicellulose (15% - 25%) impregnated with lignin (15% - 30%).
In softwood or softwood species, wooden cells are mostly of one kind, tracheids, and as a result the material is much more uniform in structure than most hardwoods. There are no vessels ("pores") on coniferous woods as is evident in oak and ash, for example.
Hardwood structures are more complex. The ability to do water is mostly treated by the ship: in some cases (oak, chestnut, ash) is quite large and different, in others (buckeye, poplar, willow) too small to be seen without hand lenses. In discussing such forests it is customary to divide them into two large, ring-porous and
classes.In a ring-porous species, such as ash, black locust, catalpa, chestnut, elm, hickory, mulberry, and oak, larger vessels or pores (as called vessel sections) are localized in the part of the growth ring that is formed. in the spring, thus forming a more or less open and porous network. The rest of the rings, produced in summer, consist of smaller vessels and a much larger proportion of wood fibers. These fibers are the elements that give strength and resilience to the wood, while the vessels are the source of weakness.
In the diffused wood pores, the pores are of equal size so that the ability to drain the water is spread throughout the growth ring rather than collected in a band or line. Examples of this type of wood are alder, basswood, birch, buckeye, maple, willow, and species populus like aspen, cottonwood and poplar. Some species, such as walnuts and cherries, are on the border between two classes, forming a middle class.
Earlywood and latewood
In softwood
In mild climates, there are often striking differences between latewood and earlywood. Latewood will be denser than that formed at the start of the season. When examined under a microscope, the densely latewood cells look very thick walled and with very small cell cavities, while those formed first in the season have thin walls and large cell cavities. Power is on the wall, not in the cavity. Therefore the greater the latewood proportion, the greater the density and strength. In choosing a piece of pine where strength or stiffness is an important consideration, the main thing to note is the comparative amount of early wood and latewood. The width of the ring is hardly as important as the proportion and nature of the latewood in the ring.
If a heavy piece of pine is compared to a lightweight piece it will be seen at once that the heavier ones contain larger latewood proportions than others, and therefore show a clearer growth ring. In the white pine there is not much contrast between the different parts of the ring, and as a result the wood texture is very uniform and easy to work. In hard pine, on the other hand, the latewood is very dense and colorful, presenting a very clear contrast with softwood, colored straws.
Not only the latewood proportions, but also the quality, are taken into account. In specimens indicating a very large proportion of latewood may look more porous and weigh less than latewood in pieces that contain little latewood. One can judge comparative density, and therefore to some extent strength, by visual inspection.
No satisfactory explanation can be given for the proper mechanism in determining the formation of early wood and latewood. Several factors may be involved. In conifers, at least, the growth rate alone does not determine the proportion of the two halves of the ring, because in some cases the slow growth wood is very hard and heavy, while on the other hand the opposite is true. The quality of the site in which the tree grows undoubtedly affects the wooden character that is formed, although it is impossible to formulate the rules governing it. In general, however, it can be said that where strength or ease of work is essential, medium to slow growth wood should be chosen.
In a porous forest
In ring-porous woods, each season's growth is always well-defined, since large pores form at the beginning of the season bordered by densely packed networks the previous year.
In the case of porous hardwood, there seems to be a fairly clear relationship between the rate of growth of wood and its properties. This can be summarized briefly in a general statement that the faster the growth or the wider the circle of growth, the harder, harder, stronger, and harder the wood. This, it must be remembered, applies only to porous woods such as oak, ash, hickory, and others of the same group, and of course, subject to some exceptions and limitations.
In a good growth-porous growth forest, it is usually the latewood where the fiber is thick-walled, which gives the most power. Because of the reduced ring width, the latewood is reduced so that very slow growth produces relatively light, porous wood consisting of thin-walled vessels and parenchyma wood. In good oak trees these early wooden vessels occupy 6 to 10 percent of the volume of logs, while inferior materials they can reach 25% or more. The latent wood of a good oak is dark and hard, and consists mostly of thick-walled fibers that make up half or more of the wood. In the inferior tree, latewood is much reduced both quantity and quality. Such variations are largely the result of growth rates.
Wood with multiple rings is often called "second growth", because of the growth of young timber in the open after the old trees have been removed faster than in the trees in the closed forest, and in the manufacture of goods where the power of important considerations such as wood materials "second growth" is preferred. This is especially true in hickory options for the grip and the fingers. Here is not only strength, but toughness and resilience are also important.
The results of a series of tests on hickory by the U.S. Forest Service. show that:
- "The greatest shock-resistant work or shock ability in woods with a wide circle having 5 to 14 rings per inch (1.8-5 mm thick rings), is fairly constant from 14 to 38 rings per inch (ring 0 , 7-1.8 mm thick), and decreases rapidly from 38 to 47 rings per inch (0.5 to 0.7 mm rings). The weight at maximum load is not so great with the fastest growing timber, with maximum of 14 to 20 rings per inch (1.3-1.8 mm thick ring), and again becomes smaller as the wood gets closer to the ring.The natural reduction is wood from a first class mechanical value indicating from 5 to 20 rings per inch (1.3- 5 mm thick rings and slower growth produce worse stocks, so hickory inspectors or buyers should discriminate against woods that have more than 20 rings per inch (rings less than 1.3 mm thick), but exceptions exist , in the normal case of growth in a dry situation, where the material is t slow growth may be strong and tough. "
The effect of growth rate on quality of chestnut wood is summarized by the same authority as follows:
- "When the ring is wide, the transition from spring wood to summer wood gradually, while in the spring wooden spring rings enter the summer timber, the spring width changes but slightly width of the annual rings, so that the narrowing or expansion of the annual rings always sacrifices the summer wood.The narrow vessels of summer wood make them richer in wood than the wood of spring consisting of a wide vessel - Specimens grown with wide rings have more wood substance rather than slow-growing trees with narrow rings, because the more wood the greater the weight, and the greater the weight of the wood, the chestnut with a wide ring must have a wood that is stronger than the chestnut with a narrow ring, according to the accepted view that the sprouts (which always has a wide ring) produces better and stronger wood than chestnut seeds, which are tumb uh slower with diameter. "
In a porous forest
In a porous forest, the demarcation between rings is not always so clear and in some cases almost (if not completely) invisible to the naked eye. Conversely, when there is a clear demarcation there may be no striking difference in the structure within the growth cycle.
In porous wood, as already stated, the vessels or pores are small, so the ability of the water to flow is spread throughout the ring rather than collected in the early wood. Therefore, the effect of growth rate is not the same as in ring-porous forest, approaching closer to conifer condition. In general it can be argued that such medium-growth forests produce stronger material than when growth is very fast or very slow. In many uses of wood, total strength is not a primary consideration. If ease of work is rewarded, timber should be chosen in conjunction with the uniformity of texture and grain straightness, which in many cases will occur when there is little contrast between latewood growth of one season and the beginning of the next season.
Monocotty wood
Ordinary resembling structural materials, "dicot" or conifer woods in rough handling characteristics are produced by a number of monocot plants, and these are also called daily wood. Of these, bamboo, botanically a member of the grass family, has considerable economic importance, larger stems are widely used as building materials and construction and in the manufacture of engineered floors, panels and veneers. The other large plant groups that produce the material often called wood is the palm tree. Less important are plants like Pandanus, Dracaena and Cordyline. With all these materials, the structure and composition of the processed raw materials is very different from ordinary wood.
Specific gravity
The only obvious feature of wood as an indicator of wood quality is the specific gravity (Timel 1986), since both pulp yield and wood strength are determined by it. Specific gravity is the ratio of mass of a substance to a mass of water of the same volume; density is the ratio of the quantity mass of a substance to that volume of quantity and is expressed in terms of mass per unit of matter, for example, grams per milliliter (g/cm 3 or g/ml). This term is essentially equivalent as long as the metric system is used. After dry, the wood shrinks and the density increases. The minimum value is associated with green wood (saturated water) and is referred to as basic specific gravity (Timel 1986).
Wood density
The density of the wood is determined by some growth and the physiological factor is aggravated to be "a characteristic of wood that is fairly easy to measure" (Elliott 1970).
Age, diameter, height, radial growth (stem), geographic location, site and growth conditions, silviculture treatments, and seed sources all to some extent affect wood density. Variations are expected. In one tree, wood density variation is often as large or even greater than that between different trees (Timel 1986). Specific gravitational variations in tree trunks can occur either in the horizontal or vertical direction.
Hard and soft wood
It is common to classify wood as either softwood or hardwood. Wood from conifers (eg pine) is called softwood, and wood from dikotillon (usually broad-leaved trees, (eg oaks) are called hardwoods These names are somewhat misleading, because hardwood is not always hard, and softwood is not soft , the famous balsa (hardwood) is actually softer than commercial softwood.Instead, some softwoods (eg yew) are harder than many hardwoods.
There is a strong relationship between the properties of the wood and the properties of the particular tree that produces it. Wood density varies with species. Wood density is correlated with its strength (mechanical properties). For example, mahogany is an excellent medium solid hardwood for fine furniture handicrafts, while light balsa, making it useful for building models. One of the densest forests is black ironwood.
Chemical wood
The chemical composition of wood varies from species to species, but about 50% carbon, 42% oxygen, 6% hydrogen, 1% nitrogen, and 1% other elements (especially calcium, potassium, sodium, magnesium, iron, and manganese). Wood also contains sulfur, chlorine, silicon, phosphorus, and other elements in small quantities.
Besides water, wood has three main components. Cellulose, a crystalline polymer derived from glucose, accounts for about 41-43%. Furthermore in abundance is hemicellulose, which is about 20% in deciduous trees but close to 30% in conifers. This is especially the five-carbon sugar that is connected irregularly, in contrast to cellulose. Lignin is the third component of about 27% in coniferous woods vs. 23% in the tree that changes leaves. Lignin bestows a hydrophobic nature that reflects the fact that it is based on an aromatic ring. These three components are intertwined, and a direct covalent link exists between lignin and hemicellulose. The main focus of the paper industry is the separation of lignin from cellulose, from which paper is made.
In chemical terms, the difference between hardwood and softwood is reflected in the composition of lignin constituents. Lignin wood is mainly derived from cyclic alcohol and coniferyl alcohol. Softwood lignin is mainly derived from coniferyl alcohol.
Extraction
In addition to lignocellulose, the wood consists of various low molecular weight organic compounds, called extractive . Extractive wood is fatty acids, resin acids, waxes and terpenes. For example, rosin is emitted by conifers as protection from insects. The extraction of this organic material from wood produces high oil, turpentine, and resin.
Usage
Fuel
Wood has a long history of being used as fuel, which continues to this day, mostly in rural areas of the world. Hardwood is preferred over softwood because it creates less smoke and burns longer. Adding a woodstove or fireplace to the house often adds to the atmosphere and warmth.
Construction
Wood has been an important construction material since humans began to build shelters, homes and boats. Almost all ships were made of wood until the late 19th century, and wood remains commonly used today in ship construction. Elm is especially used for this purpose because it rejects decay as long as it stays wet (it also works for water pipes before the advent of more modern pipes).
The wood to be used for construction works is commonly known as wood in North America. Elsewhere, wood usually refers to the felled tree, and the word for the ready-to-use sawn timber is wood . In Medieval Europe oak wood is the wood of choice for all wooden constructions, including beams, walls, doors, and floors. Currently a wider variety of wood species is used: solid wood doors are often made of poplar wood, small pine tied, and Douglas fir.
New household housing in many parts of the world today is generally made of wood-framed construction. Engineered wood products become a larger part of the construction industry. They can be used in both residential and commercial buildings as structural and aesthetic materials.
In buildings made from other materials, wood will still be found as a support material, especially in roof construction, in interior doors and their frames, and as an exterior coating.
Wood is also commonly used as a shuttering material to form molds where concrete is poured during reinforced concrete construction.
Wooden floor
The solid wood floor is a floor laid with boards or battens made from a piece of wood, usually hardwood. Because wood is hydroscopic (it obtains and loses moisture from surrounding conditions) this potential instability effectively limits the length and width of the board.
Hardwood floors are usually cheaper than engineered wood and damaged areas can be sanded and refined repeatedly, whose numbers are limited only by the thickness of the wood over the tongue.
Hardwood floors were originally used for structural purposes, which are mounted perpendicular to the building support beams (beams or carriers) and solid construction timbers are still frequently used for sport flooring as well as the most traditional wood blocks, mosaics and parquet.
Engineered Wood
Engineered wood products, building products that are glued "engineered" to specific application performance requirements, often used in construction and industrial applications. Spun-engineered wood products are produced by uniting wood, veneer, wood or other wood fiber shapes with glue to form larger and more efficient composite structural units.
These products include laminated timber (glulam), wood structural panels (including plywood, oriented strand board and composite panels), laminated veneer lumber (LVL) and other structural composite lumber (SCL) products, parallel strand wood, and I -joists. About 100 million cubic meters of wood was consumed for this purpose in 1991. The trend indicates that particle board and fiberboard will take over the plywood.
Wood that is not suitable for construction in its original form can be broken down mechanically (into fibers or chips) or chemically (into cellulose) and used as raw materials for other building materials, such as engineering wood, as well as chipboard, hardboard, and media -density fiberboard (MDF). This kind of wood derivative is widely used: wood fiber is an important component of most papers, and cellulose is used as a component of some synthetic materials. Wood derivatives can be used for floor types, such as laminate flooring.
Furniture and equipment
Wood is always used extensively for furniture, such as chairs and beds. It is also used for tool handles and cutlery, such as chopsticks, toothpicks, and other tools, such as wooden spoons and pencils.
Next generation wood products
Further developments include new lignin glue applications, recyclable food packaging, rubber tire replacement applications, anti-bacterial medical agents, and high-strength fabrics or composites. As scientists and engineers increasingly learn and develop new techniques to extract various components of wood, or alternatively to modify wood, for example by adding components to wood, more advanced new products will appear on the market. Electronic monitoring of moisture content can also improve next generation log protection.
In the art field
Timber has long been used as artistic media. It has been used to make sculptures and carvings for thousands of years. Examples include a totem pole carved by Native North Americans from the conifer stem, often Western Red Cedar ( Thuja plicata ).
Other uses of wood in art include:
- Preparation and engraving of woodcarving
- Wood can be a surface for painting, as in panel painting
- Many musical instruments are made mostly or entirely of wood
Sport and recreation equipment
Many types of sports equipment are made of wood, or built from wood in the past. For example, cricket bats are usually made of white willow. Baseball bats that are legal to use in Major League Baseball are often made of ash or hickory wood, and in recent years have been built from maple although the wood is somewhat more fragile. The NBA court has traditionally been made of parquet.
Many other types of sports and recreational equipment, such as skiing, ice hockey sticks, lacrosse sticks and arch bows, are usually made of wood in the past, but have since been replaced with more modern materials such as aluminum, titanium or composite materials such as fiberglass and carbon fiber. One noteworthy example of this trend is the family of golf clubs commonly known as jungle , heads traditionally made of persimmon wood in the early days of the game of golf, but are now generally made of metal or (especially in the case of a carbon fiber composite driver.
Degradation bacteria
Little is known about the bacteria that decrease cellulose. Symbiotic bacteria in Xylophaga may play a role in drowning wood degradation; while bacteria such as Alphaproteobacteria, Flavobacteria, Actinobacteria, Clostridia, and Bacteroidetes have had detected in submerged wood for more than a year.
See also
References
- Hoadley, R. Bruce (2000). Understanding Wood: A Craftsman's Guide to Wood Technology . Taunton Press. ISBNÃ, 1-56158-358-8.
External links
- The Wood Culture Association
- The Wood Explorer: Comprehensive database of commercial wood species
- APAÃ, - Engineering Wood Association
Source of the article : Wikipedia
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