Wood key chemical propertiesWood is composed mainly of organic substances (99% of the complete mass). Elemental chemical composition of wood of different breeds is nearly the same. Certain dry wood on average has 49% the carbon, 44% of oxygen, 6% the hydrogen, 0.1-0.3% that nitrogen. When burning wood remains its inorganic part - ash. The ingredient of the ash contains calcium, potassium, sodium, magnesium and other elements. The detailed chemical elements form the basic organic substances: cellulose, lignin and hemicelluloses. Cellulose is a herbal polymer, a polysaccharide with a lengthy chain molecule. The cellulose formula (C6H10O5) n, wherein n is the degree of polymerization, is 6000-14000. This is a very persistent substance, insoluble in water and also ordinary essential solvents (alcohol, ether, etc.), white. Beams of macromolecules of cellulose - the best fibers are referred to as microfibrils. They form the cell wall of the cabinet wall. Microfibrils are oriented mostly along the lengthy axis the the cell, between them is lignin, hemocelluloses, and also water. Lignin is a polymer of an fragrant nature (polyphenol) of complex structure; contains much more carbon and less oxygen 보다 cellulose. It is v this substance the the process of lignification that the young cell wall is associated. Lignin is chemically unstable, quickly oxidized, reacts v chlorine, dissolves as soon as heated in alkalis, aqueous remedies of sulfuric acid and also its mountain salts. Hemicellulose is a team of polysaccharides, which consists of pentosans (C5H8O4) n and hexosans (C6H10O5) n. At very first glance, the hexo-form formula is similar to the cellulose formula. However, the degree of polymerization in every hemicelluloses is much smaller and amounts to 60-200. This suggests a shorter chain the molecules and a lower resistance of this substances compared to cellulose.
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In addition to simple organic substances, wood has a reasonably small lot of extractive building material (tannins, resins, gums, pectins, fats, etc.) soluble in water, alcohol or ether. Together raw materials, hardwood is spend by three branches of the chemical industry: pulp and paper, hydrolysis and wood chemical industry. The pulp and document industry produces pulp for paper, cardboard and a variety of cellulose materials (cellulose derivatives), and wood fiber boards. Based upon the high chemical security of cellulose, by the action of miscellaneous agents, less stable building materials accompanying it are transferred to the solution. There are three teams of methods for the industrial production of cellulose: acidic, alkali and also neutral. The choice of this or that technique depends largely on the rock composition of the processed hardwood raw materials. The team of acidic methods incorporate sulfite and bisulphite. In the sulphite process, the wood of tiny spruce conifers (spruce, fir) and also a number of hardwoods is offered as a life material. The bisulphite technique makes it possible to use timber of almost any kind for the production of cellulose. To the team of alkali methods are sulphate and neutral. The many widely used sulfate method. Chopping is lugged out in a systems of sodium hydroxide and sodium sulphide. The sulphate technique makes it feasible to acquire stronger fibers. Advantages of this an approach include a much shorter duration of cooking, as well as the capacity to bring out the procedure in a closed circuit (by regenerating the liquor), i beg your pardon reduces the threat of contamination of water bodies. In this way, more than half of the pulp created in the world is produced, because it enables the use of timber of any kind.
Neutral - a technique of obtaining cellulose indigenous hardwood, in i m sorry the cooking liquor contains substances (monosulfites) having actually a reaction close come neutral. Derivatives the cellulose room widely used. In the communication of cellulose with services of caustic soda, nitric and also sulfuric mountain or acetic anhydride, man-made fabrics (staple, viscose and acetate silk), cord fiber because that the manufacture of automobile and also aircraft tires, cellophane, celluloid, film and also photographic film, nitrocellulose, nitrocellulose and also other products. The communication of aqueous remedies of acids with wood leads to the hydrolysis that cellulose and hemicelluloses, which turn into basic sugars (glucose, xylose, etc.). These sugars can be based on chemical processing, obtaining xylitol, sorbitol and also other products. However, the hydrolysis industry is greatly oriented towards the subsequent biochemical handling of sugars. The hydrolysis reaction occurs at a rather high temperature (150-190 ° C). When the hydrolyzate (an aqueous systems of straightforward sugars) is cooled, vapors room formed, indigenous the condensate of which furfural is produced. It is offered in the production of plastics, synthetic fibers (nylon), resins, the produce of drugs (furatsilina, etc.), dyes and also other products. With further processing of the hydrolyzate, fodder yeast, ethyl alcohol (ethanol), carbon dioxide space obtained. Ethanol is produced only native coniferous wood, supplied as a solvent and, increasingly, together fuel. As soon as heating hardwood without accessibility to air, pyrolysis take away place. Together a an outcome of pyrolysis, coal, zizka (liquid) and gases space formed. Charcoal, characterized by high sorption capacity, is used for cleaning industrial solutions, wastewater, in the manufacturing of sugar, in the smelting that non-ferrous metals, in the produce of clinical preparations, semiconductors, electrodes and for many other purposes. Zizka is a systems of decomposition commodities used in the manufacturing of antiseptics, phenols, acetic acids. The gases formed throughout pyrolysis of timber are supplied as fuel. In enhancement to low-quality wood, raw materials for the wood-chemical market are extractive substances. The extraction of resin (gum) native conifers is accomplished by way of a tap. To perform this, on the surface ar of the trunks of pine or cedar, a special wound (carra) is used in the fall, indigenous which the gum flows into the conical receiver. Gum processing is brought out in wood-chemical plants, where steam distillation of the volatile part - turpentine and also roast rosin take away place. Turpentine is widely supplied as a solvent in the paint and varnish industry for the production of man-made camphor. Camphor is provided in the manufacturing of cellulose, lacquers and film. Rosin is provided in the manufacturing of rubber, paper, nitrocellulose, electrical insulating materials, etc. Tannins are offered for do leathers are obtained from bark of willow, spruce, larch, fir, and additionally from oak and also chestnut wood.
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