Cork tree: description. Amazing properties of the bark. Cork is a tissue What is the stem made of

Fellems. First, a layer of phelloderm cells is formed, which forms a layer of phellogen cells. Phelogen cells are divided into two parts: upper and lower. The upper cell (fellema) immediately dies and is covered with a thick layer of suberin (a substance that does not allow water and gases to pass through). The lower cell continues to divide, forming a phellem. In some plants (for example, pine, tulip tree, euonymus), the cork consists of thin-walled corky cells and phalloids - cell layers with lignified, but not corked walls.

The cork performs the following functions:

protection against mechanical damage,
protection against the penetration of pathogens,
dry protection,
mechanical support due to the rigidity of the phellem cells.

Notes

Literature

Biological Encyclopedic Dictionary / Ch. ed. M. S. Gilyarov; Editorial: A. A. Baev, G. G. Vinberg, G. A. Zavarzin and others. - 2nd ed., corrected. - M .: Soviet Encyclopedia, 1989. - S. 506. - 864 With. - 150,600 copies. - ISBN 5-85270-002-9

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When it comes to natural sustainable building materials, one of the first materials that comes to mind is cork. Today it is used in various fields and for various purposes. Technical cork is used for heat and sound insulation of rooms, as well as a substrate for many floor coverings, such as laminate. What are the features of this material, why is it so popular - we will tell in this article, as well as dwell on the technical characteristics and methods of using technical cork.

Features of cork materials and their advantages

Why are cork materials considered environmentally friendly? The fact is that the raw material for their production is the bark of a tree - cork oak. And in the production of final materials no synthetic substances are used, the material is obtained exclusively natural.

Cork oaks grow in the Mediterranean countries, of which Portugal is considered the largest supplier of cork materials. When the age of the cork oak reaches 25 years, the bark is removed from it for the first time. Due to natural intensive regeneration, the bark grows again and the tree does not die. After 9 years, you can again remove the bark from the tree, and with each removal the quality of the bark becomes better and better.

After removal, the bark is dried in natural conditions, and then sent to a factory where various products are produced. For the production of technical cork, the bark is crushed, and then the crushed bark granules are pressed under pressure and treated with steam. At the same time, additional binders are not used, as is the case with artificial polymers, since the composition of the cork itself includes suberin, a natural glue, which is more than 45% in the material. The technology for the production of cork materials is called agglomeration, which is why the positions of technical cork are called black cork agglomerate and white cork agglomerate. They differ from each other only in that the bark of the tree branches is used for the white agglomerate, and the bark of the trunk is used for the black one.

The unique feature of cork is its honeycomb structure. For every 1 cm3 of cork, there are up to 40 million honeycomb cells. Each cell has the shape of a polyhedron with 14 faces, the internal space of the polyhedron is filled with a gaseous mixture. It is thanks to this peculiar structure that cork materials have excellent thermal insulation properties, and also do not allow water and gaseous substances to pass through. The cells are separated from each other by intercellular partitions.

Cork materials have both purely technical advantages over the rest, and have other advantages that can play a decisive role when choosing an insulating material.

Advantages of technical cork:

Full environmental friendliness and hypoallergenicity. No harmful substances are emitted from cork materials, either at rest, or when heated or burned.
Cork easily restores its shape after compression or torsion, bending. The material is exceptionally resilient. Even after years of use, it does not slip and does not get trampled, but continues to pleasantly spring underfoot.
Cork is a natural antiseptic, so building materials from it are not subject to decay and the appearance of mold fungi.
Cork is not eaten by rodents and insects.
Cork materials are not afraid of ultraviolet radiation and do not let it through.
Do not electrify, do not accumulate static electricity.
Cork materials do not emit phenols, chlorine and cyanides or other hazardous substances when burned. So that the cork does not burn, it is treated with a special substance, after which it can be attributed to class G1 (non-combustible substances).
Due to its natural unique structure, cork has a low thermal conductivity, which allows it to be used for insulation or thermal insulation of buildings.
Also, the cork has excellent soundproofing properties, reducing the noise coming from the street.
The material is comfortable to use, durable and versatile.
Safe for the environment, as it is disposed of naturally.
Technical cork retains all its properties at low temperatures, therefore it is used in the production of refrigerating chambers.
The water resistance of the cork allows you not to worry about the material even in case of flooding at home.
As exceptional features, the following can be distinguished: the cork reduces the level of radioactive radiation, and also isolates from the harmful effects of technopathogenic zones.

Also, cork materials are not afraid of alkalis and other substances.

Depending on the purpose for which it will be used, technical cork can be bought in two forms: in rolls or in sheets. They differ not only in the form of release, but also in the thickness of the material. Let us consider in more detail the characteristics and features of the use of rolled and sheet technical corks.

Technical roll cork is also called a cork substrate. It is usually produced in rolls with a width of 1000 and 1400 mm, but the thickness of the material is of greater importance. The thickness of cork in rolls can be 2 mm, 2.5 mm, 3 mm, 4 mm, 8 mm, 10 mm.

From the table above, you can get information about the technical characteristics of the rolled and sheet positions of the technical cork.

It can be added to the above that the service life of the roll substrate is equal to the service life of the building, this is one of the most durable natural materials.

Humidity material maximum 7%, which is extremely important during installation and further operation.

Permanent deformation 0.2%. Due to such low rates, the cork material does not wrinkle and returns to its original shape after prolonged loads. For example, already 1.5 minutes after the cessation of exposure, the residual deformation is only 0.35%, after 15 minutes - already 0.25%, and after 150 minutes - only 0.17%.

The roll stopper is inert in relation to various chemicals.

pay attention to sound insulation coefficient. With a cork thickness of 2 mm, it is 16 dB, and with a larger thickness (4 - 10 mm), the sound absorption coefficient can increase to 22 dB or more.

Also important sonic shock resistance- 12 dB.

Deformation modulus of elasticity 2000 - 2500 kgf/cm2. This suggests that the material is able to withstand enormous loads without significant deformation and is not subject to destruction. Thanks to these properties, it can be used on many construction sites where the pressure of heavy equipment, for example, is very high.

Rolled technical cork is used as a heat-insulating and sound-proofing material. Fits under laminate, linoleum, parquet board and panel parquet, acting as a substrate that reduces the transmission of popping sounds from movement on a wooden floor. Also, the substrate serves as a heater between the base under the floor covering and the floor covering itself.

When equipping underfloor heating, a roll cork is also used and performs all the same functions.

An important advantage of using rolled cork for arranging floors is that the material allows you to level out small irregularities in the base, and also has excellent shock-absorbing properties.

Also, a roll cork can be used for insulation and soundproofing walls and ceilings, but this is less convenient than using a sheet technical cork. The fact is that the roll cork must be straightened to fix it on the surface, and the sheets are already even. As a substrate on the floor, roll cork is ideal, as it is pressed down by the floor covering. When insulating walls and ceilings, this is inconvenient.

When laying a rolled technical cork on the floor, the temperature in the room should not be lower than +10 °C, the humidity should not be higher than 75%. Laying can begin a day after the roll is unpacked and the material is straightened. The floor screed must be level, clean and dry, the residual moisture must not exceed 2.5%. During installation, the roll is cut into the required segments, which are laid on the floor surface without gaps. The joints are carefully glued. By the way, you can not fix the roll underlay to the floor mechanically, only glue it.

Technical cork in the form of sheets differs from rolled cork only in the strength of the material and dimensions. Usually it is a plate 940x640 mm with a thickness of 2 to 10 mm. The most common positions are cork sheets with a thickness of 4, 6 and 10 mm. For sheet technical cork, the price depends on the thickness of the material, because it also affects the technical properties.

In the table of characteristics of cork sheet, it is clearly seen that the so-called white agglomerate has a large sound absorption, which means it is more suitable for soundproofing rooms.

In addition, I would like to note that the material is easily restored after pressure is applied. For example, when a load of 7 kg / cm2 is applied, the compression is 10%, and after an hour it is already 0.7%.

Sound absorption coefficient leaf cork, measured at a frequency of 2.1 kHz, is 0.85. This allows you to significantly reduce noise, as well as completely eliminate reverberation. This is especially important when soundproofing recording studios and cinemas. After all, reverberation is the propagation of the sound of a reflected sound - an echo.

Application of technical sheet cork

Sheet technical cork is used for thermal insulation and soundproofing of premises. It isolates the floor, walls, floors, ceiling. In the room, which is insulated with a technical cork, there is no echo and minimal noise from the street.

Technical cork can be found in any environment, so it can be used both for exterior facade finishing, for interior decoration of a room, and as a substrate for flooring and a “warm floor” system, like a rolled cork. As a heater, technical cork can be used in ceilings, and on the floor, and on walls, and on the roof, and on external walls.

Important! The only restriction on the use of technical cork is the production facilities where metal is processed. The fact is that metal shavings quickly clog the pores of the cork, and it ceases to perform its functions.

In combination with other materials, technical cork significantly reduces noise and reverberation. Cork is also used to reduce vibrations coming from machine tools and other mechanisms, no matter what load they put on the cork.

Cork provides the best sound absorption in the high frequency range above 1.5 kHz. This makes it possible to completely isolate the room from sharp loud sounds coming from the street, such as barking dogs or screaming. Also, when soundproofing partitions between rooms, you can isolate the room so that you will not hear the stereo system or TV.

But to reduce the vibration noise that is transmitted through the floors, or the vibration of mechanisms, the cork is not capable. Actually, like any soundproofing.

For the best sound insulation, the room is finished with cork in a complex: ceiling + walls + floor. To improve the acoustic properties of the cork, it is desirable not to cover it with another finishing material. It is possible, for example, to use cork decorative panels in addition to technical cork.

The technology of mounting a sheet technical plug is practically the same as mounting a rolled substrate. The only difference is that the sheet material can be laid immediately, as it is already even. Sheets are glued to the surface with special glue, always end-to-end. Sometimes sheets are fixed mechanically, but much less often.

And finally, the advantages of a sheet cork over a roll cork, which were noticed by professional installers:

The leaf cork is denser.
It is easier to install, since one person can handle it, unlike a rolled one, where an assistant is required.
The sheet cork does not need to be leveled.
Easier to cut to desired size.
The sheet cork does not break and crack, as it is not rolled up.

Technical cork is a versatile material that is used in almost all places where insulation is needed: both indoors and outdoors. An indisputable plus is water resistance and resistance to the influence of mold, rodents, insects. The only drawback of technical cork is the high price compared to synthetic insulating materials of the same class.

The following main functions of plant stems can be named:

movement of water and dissolved minerals from roots to leaves;

movement of organic matter from leaves to all other organs of the plant (roots, flowers, fruits, buds and shoots);

removal of leaves to sunlight and support function.

In connection with the functions performed, the stems of higher plants, especially angiosperms, acquired their characteristic internal structure.

As you know, plants stems are woody and herbaceous. According to the internal structure, they differ from each other in the stronger development of some tissues and the underdevelopment of others. The clearest picture of the internal structure of the stem can be seen on the cross section of the tree.

The stem of a woody plant usually consists of four layers: bark, cambium, wood and heartwood. Moreover, each layer can include cells of different tissues. So the composition of the bark includes peel, cork, bast fibers, sieve tubes and other tissues.

In young stems of woody plants, skin. Like the skin of leaves, it has stomata through which gas exchange occurs. Under the skin or, if it is not, on the surface is cork. In a number of trees, the cork forms a fairly thick layer. The gas exchange tube contains lentils, which are tubercles with holes. Cells of the peel and cork belong to the integumentary tissue. They protect the internal parts of the stem from damage, penetration of pathogens, and drying.

Under the cork there may be a so-called primary cortex, and already under it is bast, which consists mainly of sieve tubes And bast fibers. Sieve tubes are bundles of living cells. They move organic substances that were synthesized in the leaves during photosynthesis. Cells of bast fibers have thick walls. Bast fibers are strong enough, they perform a mechanical support function.

Under the bark is a thin layer cambium, which is an educational fabric. Its small cells actively divide during the growing season of the tree (from spring to autumn) and provide thickening of the stem. The resulting cambial cells, which are closer to the cortex, differentiate into bast cells. Those cambial cells that are closer to the wood become wood. More wood cells are formed over the summer than bast cells. On a tree saw cut, the wood cells of each year are separated from each other by darker small autumn wood cells. Thus, growth rings are visible.

Below the cambium is wood, which usually makes up the bulk of the stem of a woody plant. In the wood are vessels. An aqueous solution moves along them from the roots. The vascular cells are dead. In addition to vessels, there are other types of tissues in wood. So there are cells with thickened strong walls.

core usually consists of loose storage tissue, consisting of large cells with thin walls.

1What is the importance of peel and cork. 2Where is the bast located and what cells does it consist of. 3What is a cambium and where is it located? and got the best answer

Answer from Anastasia Popova[guru]
1) Peel and cork are integumentary tissues. The main function is to protect the plant from mechanical damage, the penetration of microorganisms, sudden temperature fluctuations, excessive evaporation, etc.
Epidermis (epidermis, skin) is the primary integumentary tissue located on the surface of leaves and young green shoots. It consists of a single layer of living, tightly closed cells that do not have chloroplasts. Cell membranes are usually sinuous, which leads to their strong closure. The outer surface of the cells of this tissue is often dressed with a cuticle or wax coating, which is an additional protective device. In the epidermis of leaves and green stems there are stomata that regulate transpiration and gas exchange of the plant.
Periderm - secondary integumentary tissue of stems and roots, replacing the epidermis in perennial (rarely annual) plants. Its formation is associated with the activity of the secondary meristem - phellogen (cork cambium), whose cells divide and differentiate in the centrifugal direction (outward) into a cork (phellem), and in the centripetal (inward) direction - into a layer of living parenchymal cells (phelloderm). Cork, phellogen and phelloderm make up the periderm.
Cork cells are impregnated with a fat-like substance - suberin - and do not allow water and air to pass through, so the contents of the cell die off and it is filled with air. The multilayer cork forms a kind of stem cover, which reliably protects the plant from adverse environmental influences. For gas exchange and transpiration of living tissues lying under the cork, the latter has special formations - lentils; these are gaps in the cork filled with loosely arranged cells.
2) Lub refers to conductive tissues. Another name is phloem. The phloem conducts organic substances synthesized in the leaves to all organs of the plant (descending current). It is a complex tissue and consists of sieve tubes with satellite cells, parenchyma, and mechanical tissue. Sieve tubes are formed by living cells located one above the other. Their transverse walls are pierced with small holes, forming, as it were, a sieve. Sieve tube cells lack nuclei, but contain cytoplasm in the central part, the strands of which pass through the through holes in the transverse septa into neighboring cells. Sieve tubes, like vessels, stretch along the entire length of the plant. Companion cells are connected to sieve tube segments by numerous plasmodesmata and, apparently, perform some of the functions lost by sieve tubes (enzyme synthesis, ATP formation).
3) Cambium is a secondary educational tissue. Located in the roots and stems of plants. It gives rise to secondary conductive tissues and ensures the growth of the plant in thickness. Cambium also plays an important role in wound healing in plants. If the outer tissues of the stem are damaged, then the cambium grows into the damaged area and differentiates into new xylem, phloem, and cambium, each of these tissues continuously continuing the corresponding type of tissue in the undamaged part of the plant.

Answer from 3 answers[guru]

Hello! Here is a selection of topics with answers to your question: 1What is the importance of peel and cork. 2Where is the bast located and what cells does it consist of. 3What is a cambium and where is it located?

Wood is one of those building materials that have been known to mankind since ancient times. The volume of its consumption is growing every year, and therefore many species are on the verge of extinction.

The latter also includes the cork tree, which has been used by man for thousands of years.

It belongs to the genus of oaks. The difference from relatives is that by about five years of age, its branches and trunk are covered with thick bark with unique properties. But you can only take it off by the age of 20. Note that you can do this up to the age (tree, of course) of 200 years!

After the first collection, at least 8-9 years are required, during which the bark is restored. A tree aged 170-200 years produces approximately 200 kg of high quality raw material.

The peculiarity of this oak is also that it belongs to the evergreen species. The leaves resemble those of Russian oaks, but are covered with a significant layer of down below. The cork tree itself is quite large: the height can reach 20 meters, and the diameter of the trunk is a meter.

Latin name - Quercus suber. It grows at an altitude of no higher than 500 meters above sea level. Most of the oaks of this species are found in Portugal, which is why the country's budget receives considerable cash injections from the export of cork, which annually increases its value.

Since ancient times, man has known that the cork tree provides this most valuable raw material, and therefore it has long been cultivated culturally. Note that there is a false representative of this genus, Q. crenata, which is quite widespread in southern Europe. Its cork layer is so small that the tree is bred exclusively for decorative purposes.

Only in Portugal more than 2 million hectares are occupied by Quercus suber oak plantations! In addition, approximately the same number of territories are used for this in all of Southern Europe.

During the year, all plantations produce more than 350 thousand tons of bark, but this amount has long been insufficient to meet demand. That is why the wild cork tree was almost completely destroyed.

By the way, what is the uniqueness of cork as a material? The fact is that it is the structure of which resembles a honeycomb in a beehive.

Each cubic centimeter of this material can contain up to 40 million of these honeycombs, which are separated from each other by partitions of the cellulose component.

Simply put, each capsule is filled with air, so that even a small piece of cork is very elastic. This property gives the material complete water resistance and the ability to restore its original state even after strong pressure.

That is why the cork tree (whose photo is in the article) has received such wide appreciation from furniture makers.

In addition, the bark contains suberin (a mixture of fatty acids, waxes and alcohols). It is unique in that it gives the tree refractory and anti-rotten qualities. There are cases when, during forest fires, cork oaks remained completely intact, with the exception of scorched bark and leaves dried from the heat.

Thus, the bark of the cork tree is a unique material given to man by nature.