Which expanded polystyrene is better. Expanded polystyrene - characteristics and selection criteria. About biological resistance

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Expanded polystyrene makes up one third of all thermal insulation materials used in the world. It is made by sintering polystyrene granules obtained through foaming with vapors of low-boiling liquids from a special suspension. At the same time, foaming components are added. In Russia, it is often called polystyrene foam. But still, there is some difference between the concepts of expanded polystyrene and polystyrene, it is not always possible to interchange them.

Answering the question, what is expanded polystyrene, it should be noted that it is a rigid gas-filled material with a cellular structure. However, there are species that do not contain gases.

Varieties of expanded polystyrene

non-pressed expanded polystyrene (PSB, PSB-S, EPS);
extruded polystyrene foam (Penoplex, Technoplex, Styreks);
press expanded polystyrene (PS-1, PS-4, as well as imported materials);
autoclave and autoclave-extrusion (exclusively imported materials).

Scope of application

It is the non-pressed polystyrene foam that is called polystyrene. The main direction of application of this material is thermal insulation, sound insulation. They insulate walls, floors, windows, balconies, etc. The popularity of this method of insulation is economically justified. If you need to access a closed area, you can simply delete the fragment and then reinstall it in its original place. Its low cost allows it to be massively used in other areas. It is often used to protect sports grounds and other objects from freezing. The specific scope of application depends on the brand.

The extrusion type is needed for thermal insulation and sound insulation of walls, facades, roofs, partitions, foundations. This type is more durable than the pressless version. This is due to the production technology. The extrusion method involves melting the original granules and then pouring the resulting mass into a mold.

Pressed polystyrene foam is taken in the manufacture of refrigerators, thermoses, vehicle bodies. It is irreplaceable in shipbuilding. Its electrical insulating properties make it popular in the electrical industry.

Packaging for products (disposable dishes, containers for fruits and meat products) and technical packaging are made of expanded polystyrene. The photo shows an example of numerous options for similar products. It has become an indispensable material for creating decorative elements.

Basic properties

Expanded polystyrene should be taken only for arranging the middle layer of structures. It perfectly tolerates temperature fluctuations from -40 ° C to 80 ° C. It is not used for warming saunas, steam rooms, heating mains. However, the properties of the material do not limit its use as insulation for buildings. Even with prolonged exposure to direct rays, it will not begin to melt or lose its structure.

There is no need to worry about the safety of the material. Styrene foam contains styrene, a substance found in many products. Its safety has been officially confirmed, styrene is recognized as non-carcinogenic, non-mutagenic, therefore it is allowed to make food packaging from this material. Donor organs and medications are even transported in polystyrene foam containers. Since it does not come into contact with the interior of the house as a heater, oxidation is impossible, therefore styrene is not released from the heat-insulating layer.

Polystyrene granules from which this material is obtained is a refined product. Therefore, it is a flammable material. It belongs to the G3 group ("normally combustible"). Often, special fire retardants are added to the plates, the action of which is based on reducing the ability to spread fire. So some modern types of material can burn on their own for no longer than 2 seconds.

Technical characteristics of expanded polystyrene

Among the technical characteristics of the material, its low thermal conductivity is of particular importance - 0.032 - 0.050 W / m * C, these indicators are significantly lower than that of brick or concrete.

The second most important characteristic is good moisture resistance. For the absorbency to be 3%, it takes about a day of water contact with the material. The vapor permeability is also very low - 0.06 mg / m * h * Pa. The extrusion variety is even lower - 0.013 mg / (m * h * Pa).

The advantages of expanded polystyrene include its inability to become an acceptable medium for biological environments. He is not afraid of fungi and mold.

In this Article: The History of the Discovery of PolystyreneCommunity Q&A production technology; spheres of application of expanded polystyrene; use in construction, GOSTs; properties and characteristics; environmental friendliness, durability and fire safety - is this insulation so safe; what the term "self-extinguishing polystyrene foam" really means; how to choose polystyrene foam

The costs of heating our houses during the cold season are very significant, and the ever-increasing cost of energy supplies increases these costs from year to year. Did you know that in cold weather, heat literally evaporates from your home, and heat losses are not just great - they are colossal! Today, most of the buildings in Russia, not protected by insulating materials, lose about 600 gigacalories of heat from each square meter, while only 40 gigacalories are spent from a square meter of housing in Germany or the United States. It turns out that homeowners actually pay for heating the street, and not their homes at all ... Insulating the walls of the building from the outside with expanded polystyrene plates can solve the problem of heat loss - but is everything so simple with this heat insulator?

History of styrofoam

It all started in 1839, when the German pharmacist Eduard Simon, experimenting with styrax (Liquidambar orientalis resin), accidentally got styrene. Having experimented a little with his discovery, the pharmacist found that the oily substance he received condenses on its own, turning into a kind of jelly. Simon did not see a practical purpose in the discovery of styrene - he called the jelly-like styrene styrene oxide and stopped further research.

In 1845, styrene interested chemists Blyth and von Hoffmann - an Englishman and a German conducted their own research, finding that this substance becomes jelly-like without oxygen. Chemists named the jelly-like styrene they obtained metastirol. 21 years later, French chemist Marceline Berthelot gave the exact name to the styrene densification process - polymerization.

Hermann Staudinger, 1935

In the 1920s, the German chemist Hermann Staudinger made an epoch-making discovery - heating styrene causes a chain reaction, during which long chains of macromolecules are formed. It was Staudinger's discovery that led to the production of polymers and plastics, for which he received the Nobel Prize in 1953.

The first styrene synthesis was carried out by researchers of the American company "The Dow Chemical Company", the commercial production of polystyrene was one of the first launched by the company "BASF" - in 1930, its engineers developed a technology for the production of polymerized styrene. In 1949, the company received a patent for the production of polystyrene balls, foamed with pentane - the very idea of this invention belongs to the chemical engineer Fritz Stäsny. On the basis of this patent, in 1951, BASF began industrial production of a heat insulator under the Styropor trademark, which is still being produced today.

The raw material for the production of all types of polystyrene insulation is granular polystyrene; a foaming agent is used to form cells. There are several stages in the technological process of obtaining expanded polystyrene:

polystyrene granules are poured into the pre-frother hopper, where they swell and acquire a spherical shape. To obtain a heat insulator of lower density, the foaming operation is repeated several times, each time reaching an ever larger ball size in order to reduce the actual weight of the expanded polystyrene;
Each foaming operation is accompanied by placing the foamed granules in a special hopper, where the inflated polystyrene balls are kept for 12 to 24 hours. During this period, the pressure inside them is stabilized, and during production by the method of suspension polymerization, they are also dried;
upon completion of a predetermined number of foaming operations and having maintained the aging period, the polystyrene balls are placed in a molding unit, where a polystyrene foam block is formed under the action of hot steam. Clamped in a narrow mold, expanded under the influence of steam, the foamed granules stick to each other, retaining their shape after cooling and removing from the mold;
at the last stage, blocks of expanded polystyrene, often having impressive dimensions, are to be cut to specified dimensions. But first, the block from the molding unit is placed in interim storage, where it is kept for about 24 hours. The fact is that under the influence of steam, the expanded polystyrene block gains excess moisture, and it will not work to perform even cutting in the wet state of expanded polystyrene, because breakages cannot be avoided. After drying, the polystyrene foam block is cut vertically or horizontally with a machine saw.

There are two main methods for the production of expanded polystyrene - suspension polymerization and polarization in bulk. Suspension polymerization technology is based on the inability of water to dissolve vinyl polymers. At the stage of foaming, styrene granules are poured into autoclave reactors with a volume of up to 50 m 3 filled with demineralized water with a polymerization initiator and an emulsion stabilizer dissolved in it. Polymerization takes place under constant pressure, with a uniform rise in temperature from the initial 40 to a maximum of 130 ° C - the whole process takes about 14 hours. The foamed polymer is removed from the reactor together with the aqueous suspension, separated from it in a centrifuge, then washed with water and undergoes a drying step. The main advantages of this technology are the constant stirring of the polymer granules inside the reactor during polymerization, efficient distribution and removal of heat, which results in a significant shelf life of the foamed polymer.

The mass polymerization technology is carried out differently - there is no water, the polymerization process is continuous and takes place at higher temperatures. In a series of mixers-reactors connected in series with each other, at a temperature from the initial 80 to the final 220 ° C, polystyrene granules are foamed. The polymerization is considered to have taken place and completed if from 80 to 90% of the original styrene is melted. When a vacuum is created in the last column-type reactor, unreacted styrene is removed, then fire retardants, dyes, stabilizers and other additives are introduced into the melt, as a result of which the polymer is granulated. The unreacted and recovered styrene is used for the next filling. It is extremely difficult to bring the process of polymerization of raw materials to obtain more than 90% of expanded polystyrene with this technology, because the reaction rate is quite high, and the possibility of heat removal is absent here.

The production of expanded polystyrene by the method of suspension polymerization is more widespread in Russia and the CIS; in the countries of the West and America, bulk polymerization technology prevails, which makes it possible to obtain a heat insulator with higher characteristics in terms of density, flexibility, clarity of borders and color, not to mention a lower percentage of waste.

The technology for producing extruded (extruded) polystyrene foam is generally similar to the polymerization technology. The difference lies in forcing the melt with added foaming agents through a press extruder, resulting in a heat insulator with cells up to 0.2 mm in diameter. It is the small size of the cells that provides extruded polystyrene foam with high performance properties and popularity in the construction industry.

Areas of use

The combination of strength and thermal insulation properties, ease of handling and processing, low cost - thanks to these characteristics, expanded polystyrene is widespread in various spheres of our life. Most often this material is used for: packaging of various goods and equipment; isothermal packaging of food products; production of disposable tableware; energy absorbers in the automotive industry; life-saving floating equipment; volumetric outdoor advertising, etc.

The absence of the threat of dusting - the main positive difference between expanded polystyrene and mineral wool, allows the use of this material for thermal insulation of refrigeration equipment in the food industry.

Expanded polystyrene is used for thermal insulation of the roadway, preventing the base from freezing. For this purpose, grades of high density expanded polystyrene are used - from 35 kg / m 3 and above. This material is also used for thermal insulation of railway tracks, effectively preventing rail distortions and their subsidence on unstable soils.

One of the first to use foam for insulating buildings was the American Hoot Heddock. According to him, the idea of thermal insulation of houses came about by accident - Huth ordered a cup of hot coffee in a cafe and suddenly noticed that the hot liquid in a disposable polystyrene glass does not burn his fingers at all. Having carried out an experiment in 1984 - having built a house in Alaska and insulated it with foam plastic - he became convinced of the effectiveness of a polystyrene heat insulator.

According to GOST 15588-86, it is permissible to use expanded polystyrene as an insulating intermediate layer of building structures. In the countries of the European Union, expanded polystyrene has been successfully used in facade insulation for more than 40 years - expanded polystyrene plates are glued to the main structural material, be it concrete or brick, from the outside (outside) side, and they are covered with a layer of plaster on top.

As noted by European architects, the use of expanded polystyrene in facade insulation cuts energy costs for heating threefold.

Plates and blocks made of extruded polystyrene foam are used as a permanent formwork and a simultaneous heat insulator. The technology used is as follows: polystyrene foam plates are installed at a given distance from each other, interconnected by a special tie system, reinforcement reinforcement is placed in the gap between the plates and concrete is poured. A variety of ready-made blocks of expanded polystyrene allows you to build facades of complex architecture. On the walls assembled from extruded polystyrene blocks and filled with concrete, a protective coating must be applied - from the outside it can be facing brick or cement-sand plaster, from the inside two layers of gypsum plasterboard jointed "at a distance" or a layer of plaster. An important condition for expanded polystyrene formwork: the density of this material in formwork blocks must be at least 35 kg / m 3.

Adhesive for expanded polystyrene should not contain organic solvents that destroy polystyrene. It is safest to use cement-based adhesives packed in 25 kg kraft bags and mixed with water - inorganic components of such mixtures will not have any negative effect on polystyrene. An important point: it is necessary to achieve the largest contact area of the expanded polystyrene plate with the insulated surface (ideally, 100% contact area) in order to exclude air sinuses that act as cold bridges and accumulate condensate.

Thermal conductivity

The high heat-insulating properties of expanded polystyrene are explained by its structure, formed by many balls welded together, which in turn consist of many cells with air enclosed in them. And since the air inside the cells is not able to move, then it is he who acts as a heat insulator - a stationary air environment has excellent insulating properties. At its core, expanded polystyrene consists of air - 98% air and only 2% of the original polystyrene.

The thermal conductivity coefficient of this material is lower than that of any other heat insulator, incl. mineral wool, and is in the range of 0.028-0.034 W / m · K. The thermal conductivity of expanded polystyrene increases with an increase in its density, for example, for extruded expanded polystyrene with a density of 45 kg / m 3, the thermal conductivity coefficient is 0.030 W / m · K. Operating temperatures at which polystyrene foam retains its properties is from -50 to +75 o C.

Water absorption and vapor permeability

If we compare extruded polystyrene foam with foam made from the same styrene, but using a slightly different technology, then the vapor permeability of the foam is zero, and the extruded polystyrene foam has a vapor permeability of 0.019-0.015 Mg / (m · h · Pa). The question arises: how is this possible, because the structure of any material made of expanded polystyrene cannot pass steam? The reason for the vapor permeability of extruded polystyrene foam, which is more dense than foam, is that steam penetrates into the balls and their constituent cells on its sides, cut during molding, while the molding of foam products is performed without cutting. With water absorption, the situation is the opposite: the foam is able to absorb up to 4% of water when immersed or in contact with it, and extruded polystyrene foam - only 0.4%, which is explained by its higher density.

Closed-cell structure of extruded polystyrene foam

Strength

In terms of strength, the undisputed leader is extruded polystyrene foam - its static bending strength is 0.4 - 1.0 kgf / m 2, foam is 0.07-0.20 kgf / m 2. The bonds between the molecules of extruded polystyrene foam are many times stronger than in the structure of foam. Therefore, the production and use of the latter is increasingly reduced - foam plastic is replaced by a more durable and modern heat insulator, which is expanded polystyrene obtained by forcing through a press extruder.

Interaction with chemical and organic products

Polystyrene foam is not affected by: mortars based on gypsum, cement, anhydrite or lime; bitumen resins, caustic soda, soap and salt solutions, mineral fertilizers, ground water and emulsions used for asphalt paving. Damage, destroy the structure and completely dissolve polystyrene foam in some cases: drying oils, some types of varnishes, organic solvents (turpentine, acetone, etc.), alcohol-containing compounds and oil products.

In addition, ultraviolet rays of the sun's rays have a destructive effect on the open surfaces of expanded polystyrene - the surface regularly irradiated by them loses its elasticity and strength, followed by the destruction of the structure of expanded polystyrene by atmospheric phenomena.

Sound conductivity

The use of expanded polystyrene for sound insulation is only partially effective - with sufficient thickness, this material is excellent for protection against impact noise, but is not able to fight airborne noise, the sound waves of which travel through the air. The inability of expanded polystyrene to extinguish airborne noise is associated with the complete isolation of its constituent cells and the significant rigidity of the outer surfaces.

Biological resistance

The vital activity of mold on the surfaces of expanded polystyrene boards is impossible - these are the results of laboratory tests in 2004, carried out in the United States by order of American producers of expanded polystyrene.

Characteristics for fire safety, environmental friendliness and durability of expanded polystyrene

Manufacturers of this heat-insulating material call it exceptionally environmentally friendly, non-combustible and retaining its operational properties for many years. Outwardly, this is how it looks - the exclusion of freon from the technological process does not harm the ozone layer, the introduction of fire retardants makes the expanded polystyrene non-combustible, and laboratory tests with dozens of freeze and thaw cycles characterize durability. However, a closer study of expanded polystyrene shows a slightly different picture ...

Air oxidation of styrene-based materials cannot be completely avoided, and the oxidation rate of foams is higher than that of extruded polystyrene foam - there are larger balls and less strong bonds in the foam structure. The higher the temperature, the higher the oxidation rate, while the foam polystyrene does not need to burn, the release of toluene, benzene, ethylbenzene, formaldehyde, acetophenone and methyl alcohol occurs during air oxidation at room temperature more than +30 ° C. In addition, freshly laid polystyrene foam releases styrene not polymerized during production. I repeat - 100% polymerization of all the feedstock in the reactor is impossible.

All types of polystyrene are combustible - from the point of view of the official classification system of building materials, those that lose their original volume when heated in air are combustible. The statements of manufacturers of polystyrene of any type about its self-attenuation do not fully reflect the fire characteristics of polystyrene, i.e. information is deliberately distorted.

Most manufacturers of this heat insulator claim that when heated, expanded polystyrene emits no more toxic substances than wood. If during the burning of a tree, chemical warfare agents are released, then this statement is true - after all, melting under the influence of heat above 80 ° C, expanded polystyrene emits a large amount of smoke and soot into the air, including small amounts of hydrobromide (hydrogen bromide), hydrocyanide (hydrocyanic acid) and carbonyldichloride (phosgene).

So what gives polystyrene foam manufacturers a claim that their product is less flammable than wood? According to Russian GOST 30244-94, such a statement would be simply impossible, because this standard classifies materials based on expanded polystyrene, as the most flammable, to groups G3 and G4. But in Europe there is a different method for assessing flammability, or rather, there are three of them - biological, chemical and complex. According to the biological method for assessing toxicity, wood materials are the most dangerous material - they quickly burn with the release of a large amount of CO2 at spontaneous combustion temperatures. But the assessment of toxicity by the biological method is given only by several final parameters that are incomparable, for example, when comparing the toxicity of combustion products of wood and polystyrene. The same is the case with the calculation of toxicity by the chemical method ...

The real picture is given only by a complex method that is unconditionally applied in Europe to all polymeric materials.

However, in Russia, suppliers of European expanded polystyrene and local manufacturers show buyers expert opinions only on biological and chemical methods, actively making these data widely public.

Another classic move, supposedly demonstrating the incombustibility of polystyrene: the stove is suspended in the air, the burner flame is directed at it - so the part of the stove, where the open flame enters, burns out, but the fire does not spread further. What conclusion can be given to polystyrene after watching this video? And no - if the same polystyrene plate is laid on a hard, non-combustible surface, then the melt drops formed during the combustion of the material will spread the high temperature and open flame throughout the entire area of the plate, which will burn completely!

The smoke production coefficient for expanded polystyrene that does not contain fire retardants is equal to 1,048 m 2 / kg, but for self-extinguishing expanded polystyrene with fire retardants introduced into its composition, this figure is higher - 1 219 m 2 / kg! For comparison: the smoke production coefficient of rubber is 850 m 2 / kg, and wood, with which manufacturers constantly compare polystyrene products, is only 23 m 2 / kg. Since for a non-specialist in matters of fire safety, the given values of smoke production do not explain anything, I will give such data - if the smoke in the room is more than 500 m 2 / kg, then absolutely nothing will be visible at arm's length.

The consequences of the burning of polystyrene are known from the tragedy of 2009 in Perm, in the Lame Horse nightclub - most of those killed in this fire suffocated by the products of the combustion of insulation, which was openly sheathed in the internal partitions. It should be noted that the owners of the club saved on insulation by using not extruded polystyrene foam, but packaging foam of a lower density, which burns excellently and is not prone to self-extinguishing.

Durability of expanded polystyrene

When buying a really high-quality thermal insulation material, observing all installation requirements, fully covering the outer area of expanded polystyrene with a layer of high-quality plaster or decorative panels, its service life will be over 30 years. But these conditions are never really met 100% - unprofessional installers, attempts by customers to reduce costs, errors in calculations and hope "at random."

A classic miscalculation is the rate on the thickness of expanded polystyrene - they say, if you mount plates of 30 cm thick, then the thermal insulation effect will increase significantly with a simultaneous increase in the service life of the material. In fact, as the thickness increases, the service life of the polystyrene thermal insulation will decrease, because significant temperature drops will cause deformation and shrinkage, forming cracks and reducing the area of direct contact of expanded polystyrene plates with the insulated surface, forming extensive air pockets. In the countries of the European Union, the thickness of polystyrene foam used for facade insulation cannot exceed 3.5 cm - this requirement, in addition to the durability of thermal insulation, is associated with fire safety, because the thinner the layer of polystyrene foam, the less combustion products it will release during a fire.

In order to reduce the threat of fire, manufacturers introduce fire retardants into polystyrene, usually hexabromocyclododexane. In Russia, expanded polystyrene with fire retardants in its composition is marked with the letter "C", meaning "self-extinguishing".

By and large, self-extinguishing polystyrene foam burns no worse than materials that do not contain a flame retardant.

The question arises - so what does the letter "C" mean? And it means that this polystyrene foam will not self-ignite when the temperature rises, nothing more. According to the degree of flammability, self-extinguishing polystyrene foam is assigned a class G2, but it should be taken into account that during the life of the fire retardant will gradually lose its properties, i.e. in a few years, the actual flammability class of such expanded polystyrene will not be higher than G3-G4.

Criteria for choosing expanded polystyrene

Cheapness, high thermal insulation qualities made polystyrene-based materials extremely popular in the construction market. And the growth in demand has led to the emergence of many enterprises, vying with each other to offer products of their own production, claiming their exceptional quality.

Be careful when choosing a brand of expanded polystyrene - as a facade insulation, it will be correct to choose PSB-S (self-extinguishing expanded polystyrene) not lower than the 40th grade. At the same time, it is worth considering a nuance - the manufacturer, within the framework of the TU developed by him, produces PSB-S-40 with a density in the range from 28 to 40 kg / m 3, and not 40 kg / m 3, as an ignorant buyer suggests, focusing on the figure in the brand ... It is quite natural that it is more profitable for the manufacturer to produce grade 40 with the lowest density, because in this way he earns more, spending less on raw materials. It makes no sense to use expanded polystyrene brands below 25 in construction - the density of such expanded polystyrene will actually correspond to packaging foam, unsuitable for facade insulation due to the rapid loss of performance.

It would be nice to find out what technological process for obtaining expanded polystyrene is used at the enterprise of this manufacturer. If an enterprise produces expanded polystyrene with a density of more than 35 kg / m 3, then this should be an extrusion method, because without compression during production, the highest density of polystyrene will not exceed 17 kg / m 3.

You can find out the quality of polystyrene by breaking it - the low-density material (used only for packaging) will break between the balls, their shape at the break point will be round, the size will be different. A break of high-quality extruded polystyrene foam will show the polyhedrons of the same size forming it, the break line will partially pass through them.

The right decision would be to purchase expanded polystyrene from well-known European manufacturers BASF, Nova Chemicals, Styrochem, Polimeri Europa or domestic Technonikol, Penoplex. The production capacity of these manufacturers of expanded polystyrene is sufficient to produce a really high-quality product.

At the end

In the presence of negative characteristics in terms of flammability and combustion products, expanded polystyrene is one of the best and, at the same time, inexpensive heat insulators. By enclosing a slab of polystyrene between two layers of cement plaster, you can get high-quality thermal insulation of buildings and premises - it is pointless to deny this fact. In Europe, about 80% of public and residential buildings are insulated along the facade with expanded polystyrene.

Expanded polystyrene as a building insulation has not yet passed the full test of time - no more than 40 years have passed since the first application.

The information widely disseminated by manufacturers about consistent quality over 80 years of operation is based on laboratory tests that can be influenced - say, by providing a special batch of samples for analysis.

When insulating facades with expanded polystyrene, it is extremely important to completely protect the outer surface of this heat insulator with a sufficient layer of plaster on a cement binder - the smallest area of contact of expanded polystyrene with the atmosphere and solar ultraviolet light will lead to its rapid destruction.

Whether it is worth insulating the interior with this material is not worth it, despite all the assurances of the manufacturers. They will give guarantees, but what good will it do in the event of a fire ...

Abdyuzhanov Rustam, rmnt.ru

There is no insulation in the world that would be argued hotter than expanded polystyrene. Flammable, toxic, unreliable - whatever claims are made to him.

But what is the real situation? How dangerous is he not from the point of view of the layman, but from the point of view of officially acting norms and standards?

Types of expanded polystyrene. Chemical composition

Depending on the manufacturing technology, expanded polystyrene (PPS) is divided into several types:

Pressless. It is designated by the abbreviations EPS (foreign production) or PSB (domestic). This is "ordinary" expanded polystyrene, most often used for wall insulation. The modified PPS is designated PSB-S, it has a lower fire hazard.
Extrusion (extruded). Designated with the abbreviation XPS, it has high compressive strength. It is used to insulate the soles of the "Swedish" foundation slab, it is laid under concrete floors or cement-sand screeds, etc.
Press (for example, PS-1 or PS-4).
Autoclave (including autoclave extrusion).

The last two types are not widely used. From the point of view of chemistry, PPS consists of expanded polystyrene. In turn, polystyrene is obtained from styrene (chemical formula С8Н8), which according to GOST 12.1.007-76 belongs to the 3rd hazard class (moderately hazardous). It is characteristic that, depending on the processing technology of the feedstock (styrene), the polystyrenes produced can be safe - they are used for making yoghurt cups, food utensils, etc.

The main characteristics of expanded polystyrene.

The main characteristics of expanded polystyrene include high thermal insulation performance, very low vapor permeability and close to zero water absorption.

As with any other material, the thermal insulation properties of PPP depend on its density. Culverting capacity depends on it. The much denser EPPS is superior to its "softer" counterpart in this respect.

Due to its strength and "hydrophobicity", it is the EPSS that is best used to insulate the basement of the building (foundations, unwinding, underground part of the walls).

Low vapor permeability forms a number of nuances of using this insulation in rooms with high humidity conditions. In industrial premises, this issue is solved by enhanced air exchange (ventilation), in residential premises - by installing windows with the function of slot ventilation.

One of the most common myths is the use of PPP as sound insulation. This myth is based on the relatively high sound insulation properties of mineral wool. Since cotton wool and PPP are the main competitors for the consumer wallet, the layman often considers them almost like equivalent materials, with the only difference that mineral wool does not burn and therefore is more expensive. In fact, mineral wool heaters, in addition to higher soundproofing properties and incombustibility, are also hygroscopic (absorb moisture) and high vapor permeability.

Biological stability and safety. Destruction. Durability

PPS and EPS do not contain substances that are attractive to microorganisms, insects and rodents. However, mold and mildew may form on the surface of these materials. In the body, PPS and EPS can also arrange holes-passages for mice and other rodents, but in general, these materials are much less attractive to them than natural ones. Thus, the "inedibility" of expanded polystyrene, as well as its "attractiveness" are myths.

The destruction of PPS is a process of chemical transformation of its structure due to oxidative processes. The reason for the latter is the high temperature (80 degrees and above), as well as the direct effect of oxygen. Therefore, expanded polystyrene is not used for thermal insulation of hot objects (for example, heating pipes) and must be protected from the effects of the external environment (most often - with a reinforcing layer over the mesh). As an example - "Two ways of reinforcing plaster when installing a wet facade on expanded polystyrene".

The average durability of the PPP is usually taken equal to 10 - 15 years. After this period, expanded polystyrene becomes brittle, the process of self-shedding begins. This does not mean that its thermal insulation properties for the 16th year of operation will be zero. This means that the warranty period of suitability is 10-15 years (different manufacturers have different ways).

It is noteworthy that for mineral wool, many manufacturers indicate an identical warranty period. Protective measures (for example, the above-mentioned reinforcement layer) increase the shelf life of this material. Thus, the unreliability of PPP in terms of shelf life is another myth.

Fire hazard

Particular attention should be paid to the fact that PPS refers to combustible materials. The use of combustible and especially combustible materials is strictly regulated by current regulatory documents. First of all, these are Federal Law No. 123 “Technical Regulations on Fire Safety Requirements”, SNiP 31-01-2003 “Residential Multi-Apartment Buildings” and SP 4.13130.2009 “Fire Protection Systems. Limiting the spread of fire. " The concept of "expanded polystyrene" does not exist for these standards. The rules for the use of combustible and combustible materials are based on such technical characteristics as flammability group, toxicity, smoke generation, etc.

Let's study the certificate for PSB-S expanded polystyrene:

Flammability group G3 (normally flammable), flammability group B2 (moderately flammable), smoke generating ability D3 (high), toxicity T2 (moderately hazardous).

The use of materials with such characteristics for decoration and / or insulation according to the standards depends on another indicator - the functional fire hazard class. The most stringent requirements among residential premises are put forward for apartment buildings. In accordance with section 5.2 of SP 4.13130.2009, apartment buildings belong to class F1.3. For him, in this document there is no prohibition on the use of materials with indicators G3, B2, D3 and T2. Section 7.3 of the fire safety requirements of SNiP 31-01-2003 also does not prohibit the use of such material.

The main requirements in terms of the use of combustible and combustible materials are given in tables 3, 27 and 28 of the Federal Law of 22.07.2008 N 123-FZ (as amended on 13.07.2015) "Technical Regulations on Fire Safety Requirements". The most stringent requirements are imposed on floors. Let's look at how a reinforced concrete fireproof floor, insulated with expanded polystyrene, will change its performance in terms of fire safety.

Table 3. Classes of fire hazard of building materials.

Table 27. List of indicators required to assess the fire hazard of building materials.

Table 28. Scope of decorative finishing, facing materials and floor coverings on the escape routes.

According to Table 3, in the case of using the material G3, B2, D3, T3 (in terms of toxicity, we have a "stock" - T2 is less toxic), we obtain the fire hazard class of building structures (insulated floors) KM4. In accordance with table 28 of the same document, classes KM1-KM3 are required for floors and ceilings (that is, safer than KM4) only for lobbies, staircases, elevator halls, common corridors and foyers.

Thus, in relation to apartment buildings (and not only), the use of combustible materials on escape routes and in crowded places is prohibited. The use of expanded polystyrene, for example, for insulation from the side of the common staircase of the adjoining kitchen wall is strictly prohibited. The norms do not prohibit at all the use of materials of the G3 flammability group in private construction facilities, there are only a number of restrictions for apartment buildings, as well as public and industrial buildings.

Additionally, you should pay attention to the fact that many laminated materials (furniture chipboard, floor coverings) often have more dangerous indicators: G4 (highly flammable), B2, D3, T3 (highly hazardous in terms of toxicity).

When calculating the fire load, such furniture, in view of its significantly greater weight than PPS (if we compare the total weight of polystyrene foam on the walls with the average filling of furniture in an ordinary room), forms a significantly greater fire hazard for humans. At the same time, there is a widespread myth in society about the extremely high danger of PPP against the background of the massive exploitation of furniture made from an even more dangerous laminated chipboard. We emphasize once again - the fire hazard is formed not only by the characteristics of the material, but also by its quantity in kilograms. The more the substance is burned, the more hazardous substances are formed. The total weight of polystyrene foam boards required for warming a room is an order of magnitude lower than the mass of the average amount of furniture in a room.

Separately, it should be noted that the modified PPS of the PSB-S brand has a self-extinguishing duration of only 4 s. That is, ignited polystyrene foam, in the absence of direct exposure to flame or spontaneous combustion temperature (more than 400 degrees), goes out on its own after 4 seconds. Furniture made of laminated chipboard cannot boast of such a characteristic.
When buying expanded polystyrene boards, require the presentation of a certificate and make sure that they have a flammability group not worse than G3 (G1 or G2 are even better, they are achieved by introducing fire retardants into the composition of the EPS during its production).

So what's the bottom line?

In our country, the attitude to "foam" is reminiscent of "sectarian religion." Someone believes in the safety of this material, while others do not, despite all the certificates, norms and GOSTs.

Evaluation of the feasibility of using PPP (EPS) in your home, especially if we talk about internal insulation, apparently, should be based not only on the characteristics of this material, but also on your attitude to your own health and environmental friendliness of the home. It is difficult to understand a person who has a long smoking experience (for example), who categorically objects to the teaching staff in view of its “non-ecological” and “fire hazard”. Of course, a bad habit does not make it right to use potentially hazardous materials in the house. But such risks of using PPP in a house (apartment), such as toxicity and fire hazard, have an incomparably lower level in relation to the conscious exposure to the body of tobacco smoke, junk food on a regular basis, a large amount of alcohol, etc.

Refusal from PPS from the point of view of possible toxicity looks advisable only with full care of one's own health - from not having bad habits, to healthy eating and not using laminated chipboard / MDF, many types of plastics, office equipment, etc. in living quarters. Perhaps this is precisely what “religion” consists in - if a person does not believe in the safety of the teaching staff, it is unlikely that he should use other, no less harmful (and often even more dangerous) substances in the room.

To the question "what is expanded polystyrene?" there is a short and concise answer. Polystyrene foam (insulation) is a modern, environmentally friendly material made of substances that are not capable of harming humans.

1 Material features

Foil polystyrene foam, like its other analogs, can be used in places where other types of heat-insulating materials cannot be used due to the fact that capillary rise of groundwater can occur there.

Thus, the use of expanded polystyrene is due to the protection of waterproofing from environmental factors that can cause irreparable harm to it.

The presented material has its own GOST. GOST 15588-86 (it is done) regulates the composition, properties and use of expanded polystyrene.

If we compare the presented insulation with a material such as mineral wool, then it is better to prefer the former.

Expanded polystyrene - insulation material for walls

The fact is that mineral wool does not have such a range of useful characteristics, although in some respects it is still better than expanded polystyrene.

In addition, mineral wool is a non-combustible material and it is incapable of harming human health. All this is indicated in the corresponding GOST.

It is best to first of all pay attention to the moisture-resistant characteristics of polystyrene foam, which are combined with its ease, reliability and durability.

When choosing a heater, it is best to give preference to expanded polystyrene, since these products are not as heavy as mineral wool and are distinguished by a high degree of ease of installation.

Externally, this insulation is presented in the form of small granules, which are sintered together under the influence of high temperatures. GOST 15588-86 strictly regulates the size of the granules of the substance.

Their size ranges from 1 to 10 mm and may depend on the intended purpose and the desired density of the product.

The GOST also states that polystyrene foam granules can be heterogeneous in structure.

Each of the granules contains a huge number of thin-walled microscopic cells. This greatly increases the parameter of the contact area of the substance with air.

The presented foam insulation is 98% air, which explains its unique properties. Reviews about this material are mostly positive, in addition to excellent heat-insulating properties, it is often mentioned that it cannot harm the human body as.

1.1 Applications of expanded polystyrene

The presented material, due to its outstanding technical and operational characteristics in the construction industry, is used almost everywhere.

Expanded polystyrene can be used as an insulating material. In addition, the product can successfully fulfill the function of a filler.

In some cases, foam can even help solve problems associated with poor soil quality.

It can be used to form embankments during roadway or bridge construction.

Expanded polystyrene PSB-S-35 2000 × 1000x180

2 Properties of expanded polystyrene

The presented material has a fairly low thermal conductivity. Thus, expanded polystyrene is an almost ideal insulation material that can provide a high heat saving capacity.

This feature is due to the structure of the material, which consists almost entirely of air.

The thermal conductivity of a substance can fluctuate between 0.032 and 0.043 W / (m ∙ K).

This indicator is many times lower than that of wood, brick, expanded clay and other insulation building materials.

The low level of thermal conductivity affects the possibility of a high level of energy supply.

The use of expanded polystyrene as a heat insulator in the construction of buildings allows, during its further operation, to significantly reduce the costs associated with heating.

High energy-saving properties make it possible to actively use the product in order to protect pipelines from excessive freezing.

The presented substance provides reliable soundproofing protection against impact noise. This effect is directly related to the ability of a substance to convert sound energy into heat energy.

Proceeding from this, due to the cellular structure of polystyrene foam, the presented material has effective sound-absorbing qualities.

It should be noted that the material has a high degree of structural stability, fluctuating over a wide temperature range.

At the same time, low temperatures are not able to affect the mechanical, chemical and physical parameters of the substance.

With an increase in temperature to + 90 ° C, even during prolonged exposure, expanded polystyrene will not radically change its properties.

Due to the fact that expanded polystyrene is completely synthetic, it is not perceived as food by insects and microorganisms, which does not contribute to their reproduction.

This material is completely unsuitable for bacteria or harmful fungus to survive in it.

The presented product is distinguished by high resistance to diffusion of water vapor and an increased coefficient of moisture resistance.

Products cannot be dissolved in water and cannot absorb it. Thus, the insulation is not subject to deformation and swelling.

This high degree of resistance to moisture contributes to the fact that foam products can be used in order to. This is especially true in situations where the insulation material is in close contact with the ground.

It should be noted that the density index of expanded polystyrene products is quite low and equals 15-50 kg / m³, however, along with this, the substance has high compressive, tensile and bending strength.

This contributes to the use of the product as a durable building material, which for a long time is able to withstand mechanical stress and at the same time not undergo deformation. Thus, due to the relatively small mass of the rearranged material, you can:

Do not use special equipment when moving products;
Reduce construction costs;
Significantly reduce the time for assembling structures.

In fact, expanded polystyrene elements are plastic, and therefore, with proper operation, the material is able to maintain its physical properties unchanged for a long time.

It is worth noting that the foam granules are composed of carbon and hydrogen molecules. This is due to the high degree of environmental friendliness of the material.

Polystyrene foam is non-toxic, dust-free and odorless.

Toxic substances are also not released from it. This insulation allows air to pass through quite easily, and therefore all structures in which it is included "breathe".

Foam blocks are easy to pre-process and do not irritate the skin and mucous membranes

As mentioned above, reviews of expanded polystyrene are mostly positive.

Vitaly, 38 years old, Kaluga:

I decided to do the insulation of the apartment and start with the loggia. I used polystyrene as an insulating material. Perfectly cut and assembled. I advise you to use it.

Sergey, 54 years old, Vologda:

I have an outbuilding in the courtyard of a private house. I decided to insulate its walls in order to live in it until late autumn. Used polystyrene foam plates. Now the warmth is kept inside very well. I recommend this material to everyone.

Vasily, 35 years old, Voronezh

I am engaged in the sale of insulation and building materials. Clients disassemble expanded polystyrene from the counter almost immediately. Everyone is very happy with it.

2.1 Which is better to choose: foam or mineral wool?

Minvata is unambiguously inferior to polystyrene in terms of thermal insulation properties. The thermal conductivity of expanded polystyrene is much better.

However, mineral wool has excellent fire safety indicators. This product is highly resistant to fire.

Foam has no such stability. The level of thermal conductivity of the foam is at a height and mineral wool loses significantly to it.

Mineral wool is highly resistant to spontaneous combustion. The vapor permeability characteristic of mineral wool is significantly superior to that of its competitor.

Along with this, the foam has a very high degree of hygroscopicity, therefore, the foam can be used in an environment with a high degree of humidity and has a low cost.

The convenience of foam lies in the fact that its weight is several times less than the weight of mineral wool, in addition, this material can be processed with ease that is not available during processing of mineral wool.

There is one drawback - polystyrene foam plates are docked with each other with some difficulties. On the other hand, mineral wool has a high degree of resistance to almost all types of organic matter and fungi.

Along with this, expanded polystyrene is largely exposed to all kinds of organic solvents, but fungi and mold do not take root on it.

It is obvious that the process of making the choice of insulation is a complex and multifaceted task. In order to solve it with a high degree of efficiency, it is necessary to carefully consider the prevailing conditions and their own priorities as well.

It is important to give preference to only well-proven heating systems. We must also remember about the correct selection of the most optimal thickness of the thermal insulation material.

Mineral wool is capable of passing moisture through itself with sufficient ease. This indicates that this material is indispensable when insulating a house built of wood or beams.

It is important to remember that wood rot quickly underneath the foam. In this case, you should first take care of the installation of the so-called parabarrier, and then fix the crate.

Mineral slabs, in most cases, are laid in two layers. This is done so that so-called "cold bridges" are not created.

From above, the material is covered with a film that provides waterproofing. When insulating a balcony, preference is almost always given to expanded polystyrene, since during installation it is not necessary to use a crate, which has a positive effect on saving the balcony area.

You should immediately pay attention to the fact that the selected insulation must necessarily correspond to the climatic conditions in which it is used.