Membrane fabric is an innovative material with selective permeability. Possesses the increased protective properties. It is used for the production of children's, sportswear, equipment for fans of active winter recreation, representatives of extreme professions.

Why are membranes needed?

Membrane fabrics: samples

The word "membrane" is of ancient origin and means "membrane". In ancient times, it was used in the ordinary and biological sense. As science developed, the term acquired a physical, chemical, technical meaning. Now membrane technologies are used in the light industry for the production of clothing.

One of the main functions of clothing is protective. Previously, rubber shoes, polyethylene raincoats, capes from others were used to protect against rain. From rain, snow, wind, these materials protected well for some period of time. It is impossible to stay in waterproof products made according to old technologies for a long time.

The human body, on average, releases more than half a liter of moisture per day, which accumulates on clothes from the inside if there is no way out. With active movements, the amount of sweat released can reach one and a half liters.

The introduction of membranes into the composition of protective fabrics allows you to remove water vapor, while preventing moisture, wind, rain, snow from getting inside.

The structure and mechanism of action of membranes

The simplest example of a membrane product is a plastic bag (not to be confused with polyethylene). If, for example, a salted protein solution is poured into a plastic bag and suspended in a container of clean water, then after a while the salt will penetrate through the pores of the cellophane into the water. Cellophane selectively lets small molecules out, retains large ones inside, water molecules from the outside do not seep into the bag.

The principle of action of membrane tissue

The membrane layer in tissues works in a similar way. It lets small molecules out without letting anything in.

Membranes used in light industry are usually divided into porous (containing pores) and non-porous (supposedly not containing pores). The division is conditional, but widespread. It is advisable to use it.

• Membranes with pores are thin polymer layers with very small holes through which gaseous water (steam) molecules can seep from the inside, but drops do not fit there. Recall the course of the school: in a drop, water molecules “stick together” - they are in the form of associated groups. In the vapor state, water molecules are alone, the distance between them does not allow them to unite. The American company Gore-TeX makes membrane fabrics from Teflon, for 1 cm 2 of which there are about one and a half billion micro-holes - pores.
• Membranes without pores act differently. They also contain many microcells with a complex, sinuous shape, reminiscent of the structure of a sponge. The steam from the skin is absorbed into the cells, saturates the membrane, turns into condensed moisture and, due to the difference in partial pressure (this concept is also from school courses), is released to the outside. This principle of separation is possible because there are more vapors inside than outside. If, hypothetically, the wearer of the clothing enters a sauna or other room with very high humidity, the moisture will enter in the same way.

In some materials, different membranes are combined, a layer without pores is laid on the outside, and with pores on the inside. The fabric is effective but expensive.

Comparison of terms of use

• All membrane tissues carry vapors from an area of ​​high pressure to an area of ​​low pressure (according to gradient experts).
• At high humidity, membranes with pores are better able to remove vapors to the outside, especially if there is ventilation on clothing. Non-porous membranes are effective in relatively dry air environments. If humidity is high or ventilation is open, such a membrane will not work well.
• At low temperatures, a membrane with pores works better. At negative temperatures of the material, pore-free membranes simply freeze.
• A porous membrane may become clogged if not properly cared for or worn. Poreless membrane fabrics are durable and last a long time.

Main characteristics

Membrane fabrics are designed to protect against the weather and create a sense of comfort for wearers. Functions justify the importance of key indicators.

• Waterproof. At high pressures of the water column, any tissue will begin to leak. For successful operation, the values ​​of the maximum tolerable impacts are important. Clothing designed for harsh conditions must withstand pressures of 20,000 mm of water column and above. A value of 10000 mm is acceptable for normal rainy conditions.
• Vapor permeability characterizes the mass of steam in grams, which can be removed by 1 m 2 of material in a given unit of time (usually 24 hours). The most common minimum vapor permeability is 3000 g/m2, the maximum is from 10000 g/m2. Sometimes this property is measured by the ability to resist steam transport (RET). If this indicator is equal to 0, the fabric completely passes all the steam, with a value of 30, the passage of steam is practically excluded.

The membrane does not perform insulating functions. It saves from rain, wind, snow, provides "breathing" to the body, helps to provide thermal comfort.

Fabric structure

Structurally, membrane fabrics differ in execution.

• In two-layer fabrics, the membrane is fixed on the inside of the fabric. Additionally, it is closed with a lining that protects against damage and clogging.
• In three-layer fabrics, the following are glued together: the outer layer, the membrane, the inner mesh. The need for a lining layer is eliminated. The material is very comfortable, it is more expensive.
• In some modifications, a special protective coating is sprayed on the inner surface of the two-layer fabric.
• There are types of membrane fabrics with a water-repellent layer (DWR) applied on top. The coating may wash off over time. It is easily restored by special means.

Leading manufacturers

Membrane fabric in clothes

The most authoritative, historically the first manufacturer of membrane fabrics is Gore-TeX. She made clothes for astronauts. Then several types of products were offered to skiers, climbers, mountain tourists.

Clothing with Triple-Point, Sympatex, ULTREX membranes is comparable in quality. The material is solid, available in several versions. The price is high, corresponds to the properties of the products.

Products with Ceplex, Fine-Tex membranes have an affordable price. It is designed for a maximum of 2 seasons of active wear, after which the material may begin to let water through a little.

When buying clothes made of membrane fabrics, pay attention to the information about gluing the seams. In some varieties, absolutely all seams are glued, in others - only the main ones. For wearing in the city, gluing the main seams is enough. For active sports, it may be better to choose products with all reinforced seams. The choice is up to the potential wearer.

Rules for the care of membrane tissues

The material is specific in composition and structure. Normal washing methods should not be applied to this group of products.

• You can wash the fabric with a membrane layer in the machine using a gentle mode and soft special products.
• You can't push in the car.
• You can't take it to the dry cleaners.
• Ironing is not necessary, it is not necessary to do this.
• Can be washed by hand if desired.
• You can leave the thing in an arbitrary straightened state so that water flows from it.
• The fabric is very slightly soiled. After wearing, drying, it can be lightly brushed with a regular brush.

Fabrics with membrane materials allow you to feel protected in any bad weather with the most active activities.

(from lat. membrana - skin, membrane) in acoustics, a flexible thin film, given external. forces into a state of tension and, as a result, elasticity. It is necessary to distinguish a plate from M., a cut depends on its material and thickness. Examples of M. - skin stretched on a drum, thin metallic. foil, which plays the role of a movable lining of a condenser microphone. Own M. are represented by systems of standing waves with one or another picture of nodal lines, to-rye separate parts of M., oscillating with opposite phases (Fig.); ext. the contour, along which the M. is clamped, is always a nodal line, if the fixation is such that there is no displacement perpendicular to the M. plane. systems of standing waves correspond to dec. oscillation frequencies, the totality of which determines the discr. own frequencies M. Forced oscillations M. under the action of concentrated or distributed periodic. ext. forces occur with a frequency of ext. impact; when it coincides with one of the properties. frequencies M. takes place.

The form of some properties. vibrations of the membrane: a - rectangular; b - round. The arrows indicate the nodal lines; i, k - numbers of harmonics.

Physical Encyclopedic Dictionary. - M.: Soviet Encyclopedia. Editor-in-Chief A. M. Prokhorov. 1983 .

(from lat. membrana - skin, membrane) - a flexible thin film, given externally. forces into a state of tension and, as a result, elasticity. M. refers to two-dimensional fluctuations. systems with distributed parameters. The elasticity of M. depends only on its material and tension, in contrast to plate, the elasticity of a cut is determined by its material and thickness. Distinguish, a feature of M. is the need to secure it on the outside. contour. Examples of M. are skin stretched over a drum, thin metallic. foil, which plays the role of a movable lining of a condenser microphone, etc.

Neglecting the dissipation of energy, oscillations of a homogeneous, uniformly stretched M. can be described by the equation

where - the displacement of the surface element M. from the equilibrium position in the direction of the normal to the plane of tension, - surface M., T- tension, - Laplace operator. Boundary conditions for M.on ext. contour; as the beginning conditions is given by the displacements and velocities of the points of the surface M. in the beginning. moment of time t= 0. Natural (free) oscillations of M. are represented by systems of standing waves. M.'s sections, oscillating with opposite phases, are separated by nodal lines. The totality of own vibration frequencies M. is a discrete spectrum. For a rectangle M. (Fig. 1) with sides a and 6 own. frequencies are expressed f-loy

The frequency w is fundamental (lowest); overtones, etc. are the harmonics of the main. frequencies. Case (square M.) called. degenerate, in square M. a simple harmonic is possible. in the form of traveling waves, while the nodal lines during the period consistently take dec. configuration.

Rice. 1. The shape of the first four natural oscillations of a rectangular membrane; arrows indicate nodal lines.

Rice. 2. The shape of a round membrane for some natural oscillations; arrows indicate nodal lines.

Own oscillation frequency of round M. (Fig. 2) radius but can be found from the equation

where J k - Bessel function of the 1st kind k th order, a k And l are the numbers of nodal diameters and nodal circles, respectively. In the case of a round M., none of the overtones is a harmonic of the main. frequency w 01 .

Forced vibrations M. occur with a frequency of ext. impact, when coinciding with a swarm with one of their own. frequency takes place resonance. M. is a sound emitter with an uneven distribution of vibrations. surface speed. Radiation M., excited on the main. frequency, has less directivity than at the same frequency of a piston diaphragm of the same configuration.

Lit.: Strett D JK. V. (Lord Rayleigh), Theory of sound, trans. from English, 2nd ed., vol. 1, M., 1955; Morse F., Fluctuations and, trans. from English, M.-L., 1949; Skuchik E., Fundamentals of acoustics, trans. from German, vol. 1, M., 1958. S. V. Egerev.

Physical encyclopedia. In 5 volumes. - M.: Soviet Encyclopedia. Editor-in-Chief A. M. Prokhorov. 1988 .

Synonyms:

See what "MEMBRANE" is in other dictionaries:

Membrane- a thin flexible plate, fixed along the perimeter, designed to separate two cavities with different pressures or separate a closed cavity from the total volume, as well as to convert pressure changes into linear movements and ... ... Dictionary-reference book of terms of normative and technical documentation

- (Membrane, diaphragm) thin, flexible, stretched plate. Round membranes, clamped around the circumference, are used in all sound transmitting and sound receiving devices (telephone, microphone, gramophone). Such a membrane easily responds to vibrations ... ... Marine Dictionary

Diaphragm, pendulum, resonator, damper; membrane, diffuser, pneumomembrane Dictionary of Russian synonyms. membrane noun, number of synonyms: 9 axolemma (1) … Synonym dictionary

membrane- Ndp. diaphragm A flexible, contoured partition separating two cavities with different pressures or separating a cavity from space and converting pressure changes into movement or vice versa [GOST 21905 76] membrane Thin flexible ... ... Technical Translator's Handbook

Membrane- * membrane * membrane is a thin boundary structure located on the surface of cells and intracellular particles, as well as tubules and vesicles in the cellular contents. Performs various biological functions provides cell permeability ... ... Genetics. encyclopedic Dictionary

- (from Latin membrana membrane) 1) in the theory of elasticity, an infinitely thin film fixed along the contour, the elastic modulus of which in the direction perpendicular to the surface is zero. 2) In technology, a thin film or plate (usually fixed along ... ... Big Encyclopedic Dictionary

MEMBRANE, in biology, the boundary layer inside or around a living CELL or TISSUE. Cell membranes include the plasma membrane surrounding the cell, the system of membranes within the cell (ENDOPLASMATIC NET) and the double membrane around the cell ... ... Scientific and technical encyclopedic dictionary

MEMBRANE, membranes, for women (lat. membrana membrane) (physical, technical). A membrane fixed along the edges or a thin plate of elastic material, capable of making the vibrations necessary to capture and reproduce sound waves. Dictionary… … Explanatory Dictionary of Ushakov

MEMBRANE, s, female. An elastic membrane, a thin film or plate capable of vibrating. M. phone. | adj. membrane, oh, oh. Membrane musical instruments. Explanatory dictionary of Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov

MEMBRANE, or membrane, a thin plate of any substance. It is used in acoustics to reproduce sound vibrations. The presence of natural vibrations in acoustic M. distorts the nature of the sound. In colloidal chemistry, M. is used for ... ... Big Medical Encyclopedia

Skiers, climbers and many other amateurs are very careful when choosing clothes for hiking. After all, during a hike it is very important that, on the one hand, it is light and not bulky clothing, and on the other hand, it provides them with dryness and warmth during the campaign. Keeping the body warm and dry helps not to get sick, because moisture or cold quite often provoke the development of various types of colds.

With the development of new technologies, membrane clothing is becoming increasingly popular among outdoor enthusiasts. It, with a sufficiently high strength and lightness, allows the body to remain warm and dry. What is a membrane, how does it differ from other types of tissue?

What is a membrane, its features and varieties?

At its core, a membrane is a multilayer fabric that consists of 2 or even more layers. External - resistant to wear, internal - soft. Between them there is still a membrane and protective layers directly. Thanks to this structure, these fabrics perfectly perform the function of protecting against wind and water.

There are several types of membrane tissues:

1. Non-porous. Such membranes do not contain micropores. As a result of this, sweat and moisture that is released by the body accumulates first on the inside and only then, through diffusion, is brought out. Under such a fabric, a person feels constantly wet, since diffusion is much slower than sweating during active movement. However, non-porous ones have many advantages, they, while retaining all the positive properties of the membrane tissue, are the most durable and unpretentious in care.
2. Pore. The tissue contains very small pores. This allows the fabric to "breathe". The fabric perfectly retains moisture that gets on it from the outside, at the same time it passes sweat and moisture from the human body to the outside. Under clothing, the body remains completely dry. With all the abundance of the above advantages, such a fabric has several disadvantages. Let's see which ones. First, the micropores become clogged over time and the benefit of a breathable and waterproof fabric is negated. Secondly, it is more demanding in care.
3. Combined. Of the above, this is the best option. In fact, it contains two layers of membrane instead of one. Closer to the body - porous, and then also non-porous on top. Thus, while retaining all the advantages of the porous membrane, it, due to the additional layer, becomes more durable and easier to operate and maintain.

In addition to varieties in structure, various fabrics are distinguished by design and texture.

By design, two-, two-and-a-half and three-layer membranes can be distinguished.

The first option is a regular fabric, from which, for example, any other item of clothing is made. Only this fabric has a membrane applied from the inside. In addition, they must have a protective lining so that the fabric does not get dirty, rub less, does not tear or clog.

In the second version, knitted pimples act as a protective layer. This allows you to reduce the weight of clothing.

Well, the last option is a three-layer one. Here comes the usual fabric, then the membrane and the mesh. All of them are bonded together with the help of lamination and look like an ordinary single-layer fabric in appearance. The inner layer also protects the suit from damage, but at the same time the weight of the clothes becomes even less.

There are also differences in the texture of the fabric. It all depends on the method of weaving the threads and their thickness. The texture, in addition to external differences, significantly affects the weight of the finished product, its water resistance and strength.

Ski suits, jackets and other warm clothes are insulated with a fabric called Twill. It is a warm and dense fabric with thick fibers, smooth and heavy-duty.

Ripstop is a lighter type of membrane and at the same time very durable. Both thin and thick fibers are used here. Such a fabric does not diverge even if it is damaged. Outwardly, it looks a bit like a honeycomb. Most often, this type of fabric is used for expensive products.

What should you pay attention to when choosing clothes from the membrane?

If you are going to buy such clothes, you should pay attention to the manufacturer, reviews about things, properties, performance characteristics, etc.

1. Manufacturer. It is difficult to talk about which manufacturer is better. There are top manufacturers who are known all over the world. For example, Toray, Event, Unitika. However, the cost of things will be significant. There are also less well-known companies - Milo, Salewa or the Chinese brand Wakarda. Here, of course, it is up to the buyer to decide, although, as practice shows, even relatively inexpensive suits from Wakarda, according to reviews, are very good in operation. The main thing is to choose the right size and parameters, study the description and characteristics of the product, take care of things.
2. Waterproof. In addition to the brand, it is worth paying attention to the waterproof parameters. In the most budget options, water resistance indicators are at the level of 3 thousand mm. Such a fabric can withstand a light drizzle, but it will no longer be able to withstand a downpour. In expensive products, this figure is about 20 thousand mm. They don't get wet even in a storm.
3. Breathability. This figure varies from 3 thousand g / m 2 per day for budget products and up to 8000 g / m 2 for expensive ones. The ability to remove accumulated sweat from under the fabric depends on it, which accordingly affects thermoregulation.
4. Seam gluing. No less important parameter. The water resistance parameter partially depends on it. Budget or urban clothing, as a rule, has sizing only at the main seams. In this case, the leakage of the seams may be. But if all the seams are glued, then leakage at the junction of the fabric is completely excluded. Such sizing is inherent in expensive models, as well as in the case of three-layer membranes.
5. Material of other layers. This setting is more relevant to . This refers to the insulation of winter clothes, because the membrane is just a thin fabric that does not heat. That is why there is a heater in winter suits. In the autumn-spring versions, it can be fleece. In winter clothing, down or its substitutes are most often used.

However, recently, especially on expensive things, another, completely new material is being used. This is Outlast phase transition insulation. It consists of microcapsules, which are capable of turning into liquid during the active movement of a person and accumulate heat. But when a person stops moving, the body cools down, these microparticles turn into a solid state and give off heat. Such things are lighter than analogues on fleece or down, however, the cost of the product is significantly increased due to insulation.

How to wear membrane clothes?

For those who use membrane clothing, it is very important to dress correctly under it. It is important to dress in layers so that.

The first layer should consist of socks and underwear with long sleeves and legs. It is better to take thermal underwear.

The next layer is insulating. If it is not very cold outside and, for example, the suit already has good insulation, then this layer can be skipped. If not, then it is better to use fleece items here, they are light, warm and breathable.

Well, the third layer is directly a membrane jacket and pants. Do not forget about the hat, because very often with the wrong choice of hats, the top of the head remains open. It is important not to forget that a person loses a lot of heat through the crown, up to 90%.

Operation features

If you have purchased or are just going to buy a ski suit or any other membrane, it is important not to forget that such things are very demanding to care for. After all, no one wants a high-quality and rather expensive thing to soon turn into an unusable rag. Such things are important to properly store, wash, iron. In addition, they also require additional care products, such as special impregnations.

1. Storage. These items are very important to store properly. Manufacturers do not recommend folding them. After all, in places of kinks, the fabric is damaged over time and loses its properties. The best storage option is hanging on a coat hanger. For safety, it is better to wear a cover on top.
2. How to wash? If we talk about washing, it is important to remember that it is worth washing such things only according to the manufacturer's instructions, which are often indicated on the label. It also indicates the temperature at which you can wash, and the mode of ironing, drying, etc. But there are also general requirements. You can not wash things in very hot water, the optimum temperature is 40 ° C, and if there are special marks on the label, then it may be less. It is necessary to wash membrane things only using special detergents, otherwise the fabric is damaged and the pores become clogged. It is also important not to forget that it is better to wash by hand, without pre-soaking, as the membrane may peel off. After washing, things are not twisted, but simply allowed to drain.
3. Drying, ironing. Drying should be unfolded, you can put it on a horizontal surface. But ironing is not recommended.
4. Impregnation. Another important step is impregnation. Impregnation allows you to save the product, significantly increases the service life. Impregnation is applied to clean things. It is worth using only the product that is intended for the specified type of fabric and type of things. For example, a suit, a hat, boots and a camping tent cannot be treated with the same impregnation. Most often these are four different types of impregnation.

Optional, but DWR coating can also be used. Such a coating has water-repellent properties, and droplets of water, falling on the surface, are not absorbed, but simply roll into balls. It extends the life of membrane things.

cell membrane also called plasma (or cytoplasmic) membrane and plasmalemma. This structure not only separates the internal contents of the cell from the external environment, but also enters into the composition of most cell organelles and the nucleus, in turn separating them from the hyaloplasm (cytosol) - the viscous-liquid part of the cytoplasm. Let's agree to call cytoplasmic membrane one that separates the contents of the cell from the external environment. The remaining terms refer to all membranes.

The structure of the cell membrane

The basis of the structure of the cell (biological) membrane is a double layer of lipids (fats). The formation of such a layer is associated with the features of their molecules. Lipids do not dissolve in water, but condense in it in their own way. One part of a single lipid molecule is a polar head (it is attracted by water, i.e., hydrophilic), and the other is a pair of long non-polar tails (this part of the molecule is repelled by water, i.e., hydrophobic). This structure of the molecules makes them "hide" their tails from the water and turn their polar heads towards the water.

As a result, a lipid bilayer is formed, in which the non-polar tails are inside (facing each other), and the polar heads are facing out (to the external environment and cytoplasm). The surface of such a membrane is hydrophilic, but inside it is hydrophobic.

In cell membranes, phospholipids predominate among lipids (they are complex lipids). Their heads contain a residue of phosphoric acid. In addition to phospholipids, there are glycolipids (lipids + carbohydrates) and cholesterol (belongs to sterols). The latter gives the membrane rigidity, being located in its thickness between the tails of the remaining lipids (cholesterol is completely hydrophobic).

Due to electrostatic interaction, certain protein molecules are attached to the charged heads of lipids, which become surface membrane proteins. Other proteins interact with non-polar tails, partially sink into the bilayer, or penetrate it through and through.

Thus, the cell membrane consists of a bilayer of lipids, surface (peripheral), immersed (semi-integral), and penetrating (integral) proteins. In addition, some proteins and lipids on the outside of the membrane are associated with carbohydrate chains.

This fluid mosaic model of the membrane structure was put forward in the 70s of the XX century. Prior to this, a sandwich model of the structure was assumed, according to which the lipid bilayer is located inside, and on the inside and outside the membrane is covered with continuous layers of surface proteins. However, the accumulation of experimental data disproved this hypothesis.

The thickness of membranes in different cells is about 8 nm. Membranes (even different sides of one) differ from each other in the percentage of different types of lipids, proteins, enzymatic activity, etc. Some membranes are more liquid and more permeable, others are more dense.

Breaks in the cell membrane easily merge due to the physicochemical characteristics of the lipid bilayer. In the plane of the membrane, lipids and proteins (unless they are fixed by the cytoskeleton) move.

Functions of the cell membrane

Most of the proteins immersed in the cell membrane perform an enzymatic function (they are enzymes). Often (especially in the membranes of cell organelles) enzymes are arranged in a certain sequence so that the reaction products catalyzed by one enzyme pass to the second, then the third, etc. A conveyor is formed that stabilizes surface proteins, because they do not allow enzymes to swim along the lipid bilayer.

The cell membrane performs a delimiting (barrier) function from the environment and at the same time a transport function. It can be said that this is its most important purpose. The cytoplasmic membrane, having strength and selective permeability, maintains the constancy of the internal composition of the cell (its homeostasis and integrity).

In this case, the transport of substances occurs in various ways. Transport along a concentration gradient involves the movement of substances from an area with a higher concentration to an area with a lower one (diffusion). So, for example, gases diffuse (CO 2, O 2).

There is also transport against the concentration gradient, but with the expenditure of energy.

Transport is passive and lightweight (when some carrier helps him). Passive diffusion across the cell membrane is possible for fat-soluble substances.

There are special proteins that make membranes permeable to sugars and other water-soluble substances. These carriers bind to transported molecules and drag them across the membrane. This is how glucose is transported into the red blood cells.

Spanning proteins, when combined, can form a pore for the movement of certain substances through the membrane. Such carriers do not move, but form a channel in the membrane and work similarly to enzymes, binding a specific substance. The transfer is carried out due to a change in the conformation of the protein, due to which channels are formed in the membrane. An example is the sodium-potassium pump.

The transport function of the eukaryotic cell membrane is also realized through endocytosis (and exocytosis). Through these mechanisms, large molecules of biopolymers, even whole cells, enter the cell (and out of it). Endo- and exocytosis are not characteristic of all eukaryotic cells (prokaryotes do not have it at all). So endocytosis is observed in protozoa and lower invertebrates; in mammals, leukocytes and macrophages absorb harmful substances and bacteria, i.e., endocytosis performs a protective function for the body.

Endocytosis is divided into phagocytosis(cytoplasm envelops large particles) and pinocytosis(capture of liquid droplets with substances dissolved in it). The mechanism of these processes is approximately the same. Absorbed substances on the cell surface are surrounded by a membrane. A vesicle (phagocytic or pinocytic) is formed, which then moves into the cell.

Exocytosis is the removal of substances from the cell by the cytoplasmic membrane (hormones, polysaccharides, proteins, fats, etc.). These substances are enclosed in membrane vesicles that fit the cell membrane. Both membranes merge and the contents are outside the cell.

The cytoplasmic membrane performs a receptor function. To do this, on its outer side there are structures that can recognize a chemical or physical stimulus. Some of the proteins penetrating the plasmalemma are connected from the outside to polysaccharide chains (forming glycoproteins). These are peculiar molecular receptors that capture hormones. When a particular hormone binds to its receptor, it changes its structure. This, in turn, triggers the cellular response mechanism. At the same time, channels can open, and certain substances can begin to enter the cell or be removed from it.

The receptor function of cell membranes has been well studied based on the action of the hormone insulin. When insulin binds to its glycoprotein receptor, the catalytic intracellular part of this protein (the enzyme adenylate cyclase) is activated. The enzyme synthesizes cyclic AMP from ATP. Already it activates or inhibits various enzymes of cellular metabolism.

The receptor function of the cytoplasmic membrane also includes the recognition of neighboring cells of the same type. Such cells are attached to each other by various intercellular contacts.

In tissues, with the help of intercellular contacts, cells can exchange information with each other using specially synthesized low molecular weight substances. One example of such an interaction is contact inhibition, when cells stop growing after receiving information that the free space is occupied.

Intercellular contacts are simple (membranes of different cells are adjacent to each other), locking (invagination of the membrane of one cell into another), desmosomes (when the membranes are connected by bundles of transverse fibers penetrating into the cytoplasm). In addition, there is a variant of intercellular contacts due to mediators (intermediaries) - synapses. In them, the signal is transmitted not only chemically, but also electrically. Synapses transmit signals between nerve cells, as well as from nerve to muscle.

Membrane- this is perhaps the main material in tourism, which causes heated debate more than others. Most likely this happens because this word is used in many other areas: from astronautics to medicine, and there is a little confusion. But in our case, the membrane is a material that is designed to protect tourists and travelers from external weather conditions and at the same time remove fumes from the inside of the product to the outside, or simply “Breathe”. We will try to use the word “breathe” less often, because it is precisely because of its misinterpretation that the membrane has become overgrown with many misconceptions.

The easiest way to imagine what a membrane is is as follows: take the most ordinary piece of polyethylene and make a thin needle with a dozen holes in it - that's all! We have a simple membrane in our hands. Like any membrane, ours has two main characteristics: water resistance and vapor permeability, and it’s pretty easy to understand what’s what. Let's put a leaky polyethylene on a flask with water. By inverting the flask and observing whether water flows through, we will find out the water resistance of our membrane. And if we boil the water in the flask and observe how much steam comes out through the holes, we will measure the vapor permeability.

Such a simple example allows us to understand the following: Membrane is the same material as base tissues, only with a different structure and chemical composition. That is, it does not have any mechanical valves that open for sweat and close from the outside from the rain (many will find this ridiculous, but after working for many years in the store, I assure you, this is not the most exotic version yet). And the second, important thing: the real membrane, like our piece of polyethylene, does not have a side - it works in both directions in the same way! This means that a drop of sweat from the inside will also not pass through the jacket, just as a drop of rain will not pass from the outside. At the same time, water vapor from the surrounding atmosphere can pass through the membrane storm in the same way as evaporation from the body goes through it.

I think I've written enough to understand that the membrane is not a magical substance that magically protects you from bad weather and instantly removes excess moisture to the outside. And now, quite naturally, the question arises: “Does the membrane work at all, and do we need it?” The answer is unequivocal - it works, and yes, it is much more comfortable with it! You don't think that the millions of dollars spent on developing hundreds of types of membranes went into needles and polyethylene, do you? I am sure not, so we will continue to talk only about modern technologies.

Membrane characteristics

As I wrote above, membranes are characterized by two main indicators: water resistance and vapor permeability. Let's analyze them in more detail.

Water resistance is the height of the water column that the membrane can withstand without getting wet. It is measured in millimeters, or another unit of measurement is used - PSI (Pounds per Square Inch - pounds of weight per square inch). All materials with a PSI value over 25 are considered to be waterproof, and a value from 1 to 24 PSI indicates water resistance of materials. We already got acquainted with this characteristic in the first article on basic materials.

And most importantly for us: the higher this indicator, the better. Only if you are not engaged in extreme tourism, it is unlikely that you should overpay for a tent with a membrane fabric of 20,000 mm.

Vapor permeability. If the meaning of this characteristic is well understood, then you can get confused in numbers and measurements, and unscrupulous manufacturers are happy to use this, indicating a huge number, indicating sometimes sad test results.

The general essence of all tests is to measure the following indicator: the amount of water in grams that will evaporate from a square meter of fabric in 24 hours (g / m2 / 24h). The indicator is abbreviated as MVTR (moisture vapor transmission rate - moisture vapor transmission rate). But how this indicator is obtained is a topic for a separate article, which we will not delve into (for those who want to do this, I recommend an article published on the website of the clothing manufacturer - Sivera). In short, the whole set of tests, one way or another, is carried out in laboratories, under certain conditions that are very different from real operation. And the most unpleasant thing for the end user is that the result of one of the tests can be an impressive number that does not reflect the essence. This value will be written on the label, and you and I will only have to trust the manufacturer. However, it is worth saying that the test labeled MVTR B2 is considered the most universal method.

Summarizing the above, I would like to say that the vapor permeability indicators on product labels should not be taken too critically. It is better to learn more about the purpose of the purchased equipment and try to choose only products from well-established manufacturers. Beware of fakes, there are a lot of them, especially the most famous brands like The North Face or Marmot. The membrane is a technologically complex thing and it physically cannot be cheap, if it is not polyethylene with holes, of course.

Membrane layers

The membrane itself is a very fragile and thin sheet of material, which in the final product must necessarily be applied to another material. It happens that the membrane in liquid form is applied to the base, in which case they speak of a membrane coating. The way in which a sheet of the finished membrane is attached to the material gives a new name - laminate.

Allocate three main types membrane designs:

Double layer, in which the membrane is protected only from the outside - marked as 2L. This method is good for saving weight and high vapor permeability, however, the inside is still protected by a lining, most often from a mesh. It is also used in clothes with an inner insulating layer.

Two and a half layers– 2.5L. As in the first case, the material has two layers, but a protective layer of non-woven material is additionally applied to the inside. Products made from such membranes are very light and compact.

3 layer construction or 3L, which means that the membrane is protected with cloth on both sides. The main advantage of such a sandwich is the maximum wear resistance of the membrane.

Almost always, the top layer of any of the structures is covered with water-repellent coatings or DWR.

Types of membranes

Hydrophobic or porous membranes. If we take our piece of polyethylene again, then it just can be classified as a “pore membrane”. That is, the material has millions of microscopic pores through which vapor molecules pass, but water drops do not pass. Only a real hydrophobic membrane is made not like us, from polyethylene, but from Teflon or polyurethane. However, these very pores become clogged over time and the material significantly loses its breathable properties. In addition, most pore membranes are not very elastic, that is, it is problematic to find “stretch” suits from it.

Hydrophilic or non-porous membranes. This type of material no longer has open pores through which steam would pass; instead, the fabric absorbs moisture and transports it to the opposite side. And here it is worth remembering that the membrane as such does not have an inner and outer side - it is the same, and there are no arrows in it that indicate the direction in which moisture needs to move. The transport of water molecules occurs due to the so-called moisture gradient. That is, moisture from the body, falling on the inner layer of clothing, begins to be absorbed into the fabric, passes from layer to layer to the opposite side and, falling on the outer part of the product, evaporates. If the humidity outside is very high, then the efficiency of moisture removal of such a membrane is significantly reduced. The chemical composition is most often polyurethane or polyester.

Combined membranes. Probably, trying to get rid of the shortcomings of porous and non-porous membranes, the manufacturers came up with the idea of ​​combining them: that is, a continuous layer of polyurethane is applied to the layer of the hydrophobic membrane. This layer is much thinner than classic non-porous fabrics and is designed to protect the more fragile structure of the pore top layer.

Which membrane to choose?

As always, there is no single answer. Each type of membrane is suitable for certain conditions, so let's highlight the main pros and cons of the three types of membranes.

Pore

+

• high efficiency of steam removal in conditions of high humidity and at low temperatures.
• good breathability
• excellent water resistance performance

-

• low elasticity
• easy to get dirty
• requires special care

Non-porous

+

• excellent breathability
• unpretentiousness
• elasticity
• good water resistance performance

-

• do not perform well in high humidity and low temperatures.

Combined

They have the same advantages as the previous ones, but there are also disadvantages of the non-porous layer, although to a much lesser extent due to the thinner layer of polyurethane.

About firms

At first glance, it seems that the number of manufacturers is simply unrealistic, since the list of names is huge. But in reality, it turns out that not so many companies produce high-quality membranes. The fact is that many brands that make clothes order membranes that are essentially the same and come up with their own names for them. For example, the widely advertised Teaxapore membrane of the German company JackWolfskin is nothing more than the long-known Entrant fabric of the Japanese company Toray, they also work closely with the American company Marmot and produce the Marmot MemBrain membrane.

Speaking of membrane companies, it is impossible not to say about Gore-tex, but rather “W. L. Gore & Associates because Gor-tex is just one of the fabrics they make. Yes, and Gor-tex has a dozen more articles with different characteristics. By the way, Gore-tex was the first to use the combined membrane technology, thereby establishing itself as an industry leader for many years.

Another interesting membrane is eVent. Its peculiarity is that although it is a porous membrane, its fibers are covered with polyurethane; while at the same Gore-tex polyurethane is applied in a continuous layer on the main film. This greatly increases the breathability of the fabric. eVent is a rather expensive material and, moreover, there are difficulties with gluing seams on products made from this membrane, as a result, the price of the final product is quite high.

You can delve into the names and technologies used for a long time, but, as it seems to me, the real qualities of products made from membrane fabric can only be learned from personal experience. A lot of factors affect the behavior of the membrane in different conditions, and what is ideal for one person will not be at all like another. With experience, you yourself will understand what points to pay more attention to, and what you can close your eyes to. For the very first purchases, as always, I advise you to listen to the descriptions and advice of the clothing and equipment manufacturers themselves. Believe me, they do a very great job of designing and building models and all this for you and me. Of course, their goal is to make money, but self-respecting brands are primarily aimed at long-term friendship with us, so do not be afraid to trust those whose profession is to create comfortable conditions in the toughest and most unpredictable situations.

In custody

The membrane is a great thing with which your hobbies will become much more comfortable! Just do not forget that this is not a magical shell. In any case, a person sweats - this is a natural process - the membrane only helps to evaporate this moisture to the outside. And, at the same time, not every membrane windbreaker can withstand many hours under a torrential downpour. But it will be a much more comfortable watch than if you were climbing uphill in a rubber, absolutely waterproof raincoat. Many skeptics will dissuade you with shouts, there is nothing cooler than a tarpaulin, but I persuade you to try and not be skeptical, but try to understand your feelings and form your own opinion about the membrane.

I hope this article will be useful to you, but in the next one, we will talk about heaters. More travels and see you soon!