Nature has created many organisms and cells, but despite this, the structure and most of the functions of biological membranes are the same, which allows us to consider their structure and study their key properties without being tied to a particular type of cell.
What is a membrane?
Membranes are a protective element that is an integral part of the cell of any living organism.
The structural and functional unit of all living organisms on the planet is a cell. Its vital activity is inextricably linked with the environment with which it exchanges energy, information, matter. Thus, the nutritional energy necessary for the functioning of the cell comes from outside and is spent on the implementation of its various functions.
Structure of the simplest structural unit of a living organism: cell membrane, nucleus, organelles, various inclusions. It is surrounded by a membrane, inside which the nucleus and all organelles are located. These are mitochondria, lysosomes, ribosomes, Golgi apparatus, endoplasmic reticulum. Each structural element has its own membrane.
Role in cell life
The biological membrane plays a culminating role in the structure and functioning of an elementary living system. Only a cell surrounded by a protective shell can rightly be called an organism. A process such as metabolism is also carried out due to the presence of a membrane. If its structural integrity is broken, this leads to a change in the functional state of the organism as a whole.
Cell membrane and its functions
It separates the cytoplasm of the cell from the external environment or from the shell. The cell membrane ensures the proper performance of specific functions, the specifics of intercellular contacts and immune manifestations, and supports the transmembrane difference in electrical potential. It contains receptors that can perceive chemical signals - hormones, mediators and other biologically active components. These receptors give it another ability - to change the metabolic activity of the cell.
Membrane functions:
1. Active transport of substances.
2. Passive transfer of substances:
2.1. Diffusion is simple.
2.2. Transfer through the pores.
2.3. Transport carried out by diffusion of a carrier along with a membrane substance or by relaying a substance along the molecular chain of a carrier.
3. Transfer of non-electrolytes through simple and facilitated diffusion.
4. Active ion transport.
Structure of the cell membrane
The components of the cell membrane are lipids and proteins.
Lipids: phospholipids, phosphatidylethanolamine, sphingomyelin,phosphatidylinositol and phosphatidylserine, glycolipids. The proportion of lipids is 40-90%.
Proteins: peripheral, integral (glycoproteins), spectrin, actin, cytoskeleton.
The main structural element is a double layer of phospholipid molecules.
Roof membrane: definition and typology
Some statistics. On the territory of the Russian Federation, the membrane has been used as a roofing material not so long ago. The share of membrane roofs from the total number of soft roof slabs is only 1.5%. Bituminous and mastic roofs have become more widespread in Russia. But in Western Europe, membrane roofs account for 87%. The difference is palpable.
As a general rule, the membrane as the main material for roof covering is ideal for flat roofs. For those with a large bias, it is less suitable.
The volumes of production and sales of membrane roofs in the domestic market have a positive growth trend. Why? The reasons are more than clear:
- The service life is about 60 years. Imagine, only the warranty period of use, which is set by the manufacturer, reaches 20 years.
- Easy to install. For comparison: the installation of a bituminous roof takes 1.5 times more time than the installation of a membrane floor.
- Easy to maintain and repair.
The thickness of roofing membranes can be 0.8-2mm, and the average weight of one square meter is 1.3kg.
Properties of roofing membranes:
- elasticity;
- strength;
- resistance to UV rays and other aggressive environments;
- frost resistance;
- fire resistance.
Roofing membrane is of three types. The main classification feature is the type of polymeric material that makes up the base of the canvas. So, roofing membranes are:
- EPDM. Membranes belonging to the EPDM group are made on the basis of polymerized ethylene-propylene-diene monomer, or, more simply, synthetic rubber. Advantages: high strength, elasticity, water resistance, environmental friendliness, low cost. Disadvantages: adhesive technology for joining canvases using a special tape, low strength joints. Scope of application: used as a waterproofing material for tunnel ceilings, water sources, waste storage, artificial and natural reservoirs, etc.
- PVC membranes. These are shells, in the production of which polyvinyl chloride is used as the main material. Advantages: UV resistance, fire resistance, extensive color range of membrane sheets. Disadvantages: low resistance to bituminous materials, oils, solvents; emits harmful substances into the atmosphere; the color of the canvas fades over time.
- TPO. Made from thermoplastic olefins. They can be reinforced and non-reinforced. The first are equipped with a polyester mesh or fiberglass cloth. Advantages: environmental friendliness, durability, high elasticity, temperature resistance (asat high and at low temperatures), welded joints of the seams of the sheets. Disadvantages: high price category, lack of manufacturers in the domestic market.
Profiled membrane: features, functions and benefits
Profiled membranes are an innovation in the construction market. Such a membrane is used as a waterproofing material.
The substance used in the manufacture is polyethylene. The latter comes in two types: high pressure polyethylene (LDPE) and low pressure polyethylene (HDPE).
| Indicator | PVD | PND |
| Tear Strength (MPa) | 13 | 23 |
| Tensile elongation (%) | 400 | 100 |
| Density (kg/m3) | 917-930 | 948-952 |
| Compressive strength (MPa) | 12 | 20-36 |
| Notched impact strength (KJ/sqm) | - | 2-50 |
| Bending modulus (MPa) | 140-250 | 600-850 |
| Hardness (MPa) | 14-25 | 45-59 |
| Operating temperature (˚C) | from -60 to +80 | from -60 to +80 |
| Daily water absorption rate (%) | 0, 01 | 0, 01 |
Profiled high pressure polyethylene membrane has a special surface - hollow pimples. The height of these formations can vary from 7 to 20 mm. The inner surface of the membrane is smooth. This enables trouble-free bending of building materials.
Changing the shape of individual sections of the membrane is excluded, since the pressure over its entire area is distributed evenly due to the presence of all the same protrusions. Geomembrane can be used as ventilation insulation. In this case, free heat exchange is ensured inside the building.
Advantages of profiled membranes:
- increased strength;
- heat resistance;
- resistance of chemical and biological influences;
- long service life (over 50 years);
- easy to install and maintain;
- affordable price.
Profiled membranes come in three types:
- with a single layer;
- with two-layer canvas=geotextile + drainage membrane;
- with three-layer canvas=slippery surface + geotextile + drainage membrane.
Single-layer profiled membrane is used to protect the main waterproofing, installation and dismantling of concrete walls with high humidity. A two-layer protective one is used when equipping wall drainage. Consisting of three layers, it is used on soil that lends itself to frost heaving, and soil that is deep.
Uses of drainage membranes
The profiled membrane finds its application in the following areas:
- Basic foundation waterproofing. Provides reliable protection against the damaging effects of groundwater, plant root systems, soil subsidence, mechanical damage.
- Wall foundation drainage. Neutralizes the impact of groundwater, precipitation by transferring them to drainage systems.
- Horizontal Reservoir Type Drainage – Deformation Protection Due to Structural Features.
- Analogue of concrete preparation. It is used in the case of construction work on the construction of buildings in the zone of low groundwater, in cases where horizontal waterproofing is used to protect against capillary moisture. Also, the functions of the profiled membrane include the impermeability of cement laitance into the soil.
- Ventilation of high humidity wall surfaces. It can be installed both on the inside and on the outside of the room. In the first case, air circulation is activated, and in the second, optimal humidity and temperature are ensured.
- Used inverted roof.
Super diffusion membrane
Superdiffusion membrane is a new generation material, the main purpose of which is to protect elementsroof structure from wind, precipitation, steam.
The production of protective material is based on the use of non-woven materials, high quality dense fibers. In the domestic market, a three-layer and four-layer membrane is popular. Reviews from experts and consumers confirm that the more layers underlie the design, the stronger its protective functions, and therefore the higher the energy efficiency of the room as a whole.
Depending on the type of roof, its design features, climatic conditions, manufacturers recommend giving preference to one or another type of diffusion membranes. So, they exist for pitched roofs of complex and simple structures, for pitched roofs with a minimum slope, for folded roofs, etc.
Superdiffusion membrane is laid directly on the thermal insulation layer, plank flooring. There is no need for a ventilation gap. The material is fastened with special brackets or steel nails. The edges of the diffusion sheets are connected with mounting tape. Installation work can be carried out even under extreme conditions: on a frosty morning, with strong gusts of wind, etc.
In addition, the coating in question can be used as a temporary roof covering.
PVC membranes: essence and purpose
PFC membranes are a roofing material made from polyvinyl chloride with elastic properties. Such modern roofing material doesdisplaced bituminous roll analogues, which have a significant drawback - the need for systematic maintenance and repair. Today, the characteristic features of PVC membranes make it possible to use them when carrying out repair work on old flat roofs. They are also used when installing new roofs.
A roof made of this material is easy to use, and its installation is possible on any type of surface, at any time of the year and under any weather conditions. The PVC membrane has the following properties:
- strength;
- resistance to UV rays, various types of precipitation, point and surface loads.
It is thanks to its unique properties that PVC membranes will serve you faithfully for many years. The life of such a roof is equal to the life of the building itself, while rolled roofing materials need regular repairs, and in some cases even dismantling and installing a new floor.
Membrane sheets made of PVC are connected to each other by hot breath welding, the temperature of which is in the range of 400-600 degrees Celsius. This connection is completely sealed.
Advantages of PVC membranes
Their merits are obvious:
- flexibility of the roofing system, which is the most consistent with the construction project;
- durable, airtight connecting seam between membrane sheets;
- ideal change toleranceclimate, weather conditions, temperature, humidity;
- increased vapor permeability, which contributes to the evaporation of moisture accumulated in the under-roof space;
- many color options;
- fire-fighting properties;
- ability to maintain original properties and appearance for a long period;
- PVC membrane is an absolutely environmentally friendly material, which is confirmed by the relevant certificates;
- the installation process is mechanized, so it won't take long;
- operational rules allow the installation of various architectural additions directly on top of the PVC membrane roof itself;
- single layer styling saves you money;
- easy to maintain and repair.
Membrane fabric
The textile industry has long known membrane fabric. Shoes and clothes are made from this material: for adults and children. Membrane - the basis of membrane fabric, presented in the form of a thin polymer film and having such characteristics as water resistance and vapor permeability. For the production of this material, this film is covered with outer and inner protective layers. Their structure is determined by the membrane itself. This is done in order to preserve all useful properties even in case of damage. In other words, membrane clothing does not get wet when exposed to precipitation in the form of snow or rain, but at the same time it perfectly passes steam from the body into the external environment. This bandwidth allows the skin to breathe.
All things consideredThe foregoing, we can conclude that ideal winter clothes are made from such a fabric. The membrane at the base of the fabric, while it can be:
- with pores;
- no pores;
- combined.
Membranes with many micropores contain Teflon. The dimensions of such pores do not even reach the dimensions of a drop of water, but are larger than a water molecule, which indicates water resistance and the ability to remove sweat.
Membranes that do not have pores are usually made from polyurethane. Their inner layer concentrates all sweat-fat secretions of the human body and pushes them out.
The structure of the combined membrane implies the presence of two layers: porous and smooth. This fabric has high quality characteristics and will last for many years.
Thanks to these advantages, clothes and shoes made of membrane fabrics and designed to be worn in the winter season are durable, but light, and perfectly protect against frost, moisture, and dust. They are simply indispensable for many active types of winter recreation, mountaineering.
