Expanded polystyrene properties. Advantages of using expanded polystyrene as a heater. Extruded polystyrene foam boards

What is extruded polystyrene foam? Extruded (extruded) expanded polystyrene is a synthetic material for thermal insulation developed by an American construction company in the 1950s. It is made using foaming technology, polymer compositions are used in the composition. The material is pressed through a special mold and combined into a single piece.

Produced in the form of plates, substrates. It is found on the market as a decorative element. The standard plate size is 600x1200 or 600x2400 mm. Standard dimensions are set by GOSTs, but many companies change the dimensions by making plates of a different width. A common size is 580 mm. The thickness of the elements varies from 20 mm to 10 cm, depending on the manufacturer.

The material is delivered to retail outlets in packages of several elements. The number of units in one package depends on the thickness of the products. For example, if the thickness of the boards is 5 cm, the package usually contains 8 items. With a thickness of 10 cm, 4 plates are packed.

Additional Information: production of expanded polystyrene as a floor covering is possible. The modern market offers materials for laminate, parquet, linoleum. Production on the basis of material of decorative elements is possible. They look exactly like plaster.

Like any other material, extruded polystyrene foam has advantages and some disadvantages. Before purchasing and using it is worth familiarizing yourself with them.

Advantages of extruded polystyrene foam:

• Moisture absorption within 0.2%. This indicator means almost complete water resistance.
• Minimum thermal conductivity. At a standard temperature of 25 ° C, it is about 0.032 W / m * K. If we compare the conductivity of heat, the following results in terms of indicators: 55 cm of brick is equal to 3 cm of polystyrene foam.
• Good resistance to deformation. It can be used for laying under the blind area, laying after the foundation.
• Does not react with inorganic chemicals.
• Withstands significant temperature fluctuations, the performance does not change at air temperatures from -50 to +75 ° C.
• According to the documentation, the material can be used for at least half a century. During this time, the characteristics will not change.
• Environmentally friendly substance. It is used not only as a heater, but, for example, for the production of light disposable plates or other types of cheap dishes. Children's toys are made from it.
• Has a minimum weight. A small thickness is enough for good insulation.

In addition to numerous positive characteristics, there are some disadvantages:

• comparison with other types of heaters shows that the price of the material is high;
• strong flammability. In the process of combustion, harmful substances, black smoke are released;
• under the influence of infrared rays is destroyed. To maintain performance, it must be hidden from direct sunlight;
• manufacturers assure that rodents do not start inside the insulation. Indeed, they do not live inside, but often make channels for movement;
• solvents destroy the structure.

In addition to the above disadvantages, low vapor permeability can be added to them. Sometimes that's a plus, but if it's possible mold. As a result, an unpleasant smell appears in the dwelling, dampness is constantly felt.

Application area

Extruded gray polystyrene foam has a wide range of applications. Mainly used for insulation work. The scope of use is limited only by temperature indicators (not higher than 75 ° C). The material can be laid in damp places, in the ground.

Usually the scope of use is limited only by financial possibilities. The high cost makes it impractical to use in many places. In places where there is no need for high technical characteristics, instead of PPS, reviews about which are also positive are used to save money.

Used for insulation:

• concrete or wooden;
• indoors or outside the building. Compatible with any material;
• . It is not uncommon for concrete rings to be coated with a material for additional protection;
• the surface of the earth. To prevent destruction of the structure, paint is applied. Even a thin layer will not allow damage to the composition.

In addition to these areas, the material is used in road construction. Included in many refrigeration units as an extrusion heater. Used in agriculture. Expanded polystyrene insulates roofs, underground floors. One of the promising areas is the production of sandwich panels.

Specifications of extruded polystyrene foam

The material has one of the highest technical characteristics on the market for insulation products. Any gas has a much lower thermal conductivity than solids. For air, the indicator is 0.026 W / m * o C. Extruded polystyrene foam is an air mixture of about 90%. It has a thermal conductivity of 0.03 W / m * o C. Almost like air, which means that heat is perfectly retained.

The material is produced with different densities. Manufacturers offer from 25 to 47 kg / m 3. The higher the number, the greater the strength. As density increases, strength increases from 20,000 to 50,000 kg/m 2 .

Water is poorly absorbed by polystyrene foam. In about a month, one tile is able to absorb about 0.4% of its own volume if it is completely immersed in water. Further, the percentage of absorbed fluid does not increase, but stops. Vapor permeability is minimal. It is 0.0128 Mg / (m * h * Pa). Often companies specializing in repair work suggest not to use a vapor barrier, limiting themselves to using only polystyrene.

The insulation is able to withstand temperatures ranging from -50 to +75 ° C. Its use is possible in almost any climate. Flammability is high, the class varies depending on the addition of additional substances, from G1 to G4.

Some models have a special notch along the edges. Made to increase the density of the boards by insulating the seams. This innovation prevents the formation of layers of cold between the elements, ensuring complete preservation of heat.

Tests have been carried out with expanded polystyrene. Their meaning is repeated freezing, thawing of wet tiles. It was determined empirically that without changing the technical characteristics, the material can withstand 80 cycles. For users, this information is useful: for about so many years the composition can withstand operation.

Additional Information: Compared to polystyrene foam, polystyrene foam wins in terms of heat preservation by about 2 times. Increased strength, reduced thickness. Compared to other heaters, sound transmission is not very high. The lack of ease of installation is compensated. It is completely safe for health.

Material selection rules

Demand for expanded polystyrene is high, increasing annually. In order for the insulation to last as long as possible, to perform all the required functions without failures, it is necessary to make the right purchase. Each manufacturer claims that his product is the best on the market, but this is not always true.

Selection rules:

• Polystyrene is designated by two numbers. If the marking is below index 28, you should refuse to buy. Checking is required, some brands of the product are not suitable for facade work, they will not cope with the insulation of the house. Choose material with an index of 40 or higher. The PSB-S-40 brand, a self-extinguishing composition, has proven itself well.
• Before buying, look at the standards on the basis of which production was carried out. Many manufacturers make plates not according to GOSTs, but to their own specifications. Possibly defective product. Usually the density is reduced, thereby reducing the cost. You should not focus on the number of the brand, be sure to familiarize yourself with the characteristics.
• To ensure the high quality of the product, you can break off a small piece from the edge. If small balls are visible at the fracture site, the styrofoam is probably low grade. At the break, there should be polyhedrons of regular shape. The broken piece is flat. The test shows the method of production: extrusion performed on professional equipment, or an artisanal method, like a simple foam.
• Purchase goods from reputable manufacturers. These are Penoplex URSA, Knauf and TechnoNIKOL - Russians. Basf or Novachemicals are foreign.

Do not forget that the production of expanded polystyrene is a complex technological process. Production methods differ among many manufacturers. Some are safe, others can be harmful to human health.

Manufacturer's marks

Each brand of expanded polystyrene manufacturer differs from its competitors in some features. To understand the variety of the proposed choice, it is worth considering the products of each manufacturer in more detail.

Knauf

Manufacturer from Germany. Production is represented by numerous options for expanded polystyrene.

heaters are used:

• Knauf Therm Compact. Universal, used for any kind of household thermal insulation. It has a low coefficient of thermal conductivity of 0.032 W / mk, high soundproofing properties. The airborne noise reduction index is 47 dB, impact noise is damped if the figure does not exceed 24 dB. Due to its performance, it is well suited for warming small rooms.

Supplied in slabs 1x0.6 m long. Thickness 5 cm. Vapor permeability 0.033 mg/mchPa

• Knauf Therm Roof Light. Density is low, 10–15 kg/m³. used to retain heat on the roof frames of houses. Characteristics: heat conductivity 0.034 W / mk, steam conductivity - 0.035 W / mk.
• Knauf Therm Wall - for wall insulation. The indicators coincide with previous designs, the increased mechanical strength is different. 60 kPa - an indicator of compressive strength. The choice of plate sizes is wide. Thermal conductivity: 0.033 W / mk, steam conductivity: 0.032 mg / mchPa. G3 - flammability class.

There are models Knauf Therm Flor, suitable for floor insulation, with a low thermal conductivity of 0.03 W / mk and Knauf Therm 5 in 1. The latter stands out for the maximum durability among all models of the company. Withstands up to 17 t/m 2 .

The manufacturer of expanded polystyrene URSA from Russia presents several product options.

Products differ from other manufacturers in increased strength indicators. The material is indispensable for professional construction. One of the most durable options that can withstand significant loads.

Penoplex

Domestic manufacturer of expanded polystyrene. Has a wide range of models. Plates can be used for various insulation options.

There are the following types of products:

• Penoplex Wall

• Penoplex Foundation

• Penoplex Roof

• Penoplex Comfort

• Penoplex 45

It is considered a leader in the field of insulating materials. Every year the volume of products produced has increased rapidly. Now heaters are a little more expensive than competitors on the Russian market, but the quality of the goods is the highest. It specializes in the production of numerous types of various heaters. Expanded polystyrene is represented by several models.

Frequently asked Questions

- What is better under the screed - expanded clay or expanded polystyrene?

The thermal conductivity coefficient of expanded clay is on average 0.12, and foam 0.03 W / m * C. Those. almost in order. Thus, to ensure the required thermal insulation of the floors, the kermazite backfill will be much thicker than laying foam sheets and the like. And as a result, the entire construction of expanded clay floors will be much thicker than the construction of foam floors.

- Polyurethane foam or expanded polystyrene which is better?

After a comparative analysis of both heaters, we can say the following: polyurethane foam has higher characteristics in terms of sound insulation, moisture resistance, and heat resistance. It has a higher class of fire safety. However, its thermal conductivity is much lower.

Considering that we are talking about the choice of material for insulation, polystyrene foam will be the best. Although, given the experience of users, there is no need to use a material with such high performance as polystyrene. Therefore, preference when buying should be given to polyurethane foam.

Is styrofoam harmful to human health?

No, the material when used. The only thing is that acrid smoke is released during combustion.

What surfaces cannot be insulated with polystyrene foam?

It is impossible to insulate surfaces whose temperature exceeds the specified limits: -50 ... +75 ° С. Another limitation: in wooden houses where good vapor barrier is required, it is undesirable to use the material. Perhaps the formation of mold, fungus between the wall and the insulation. Moist air will not come out of the house. There will be constant high humidity in the room.

What is extruded polystyrene foam? Universal heater. It is considered one of the modern examples of materials of this class. When using it, it is worth observing the established temperature standards and other important requirements. If the EPS insulation is done correctly, manufacturers give a guarantee for the service life of polystyrene for at least 50 years.

Expanded polystyrene is a polymer gas-filled material that can be obtained by foaming polystyrene and other components. The structure of the presented material is closed. At 98% it consists of gas, therefore it is able to provide good heat and sound insulation properties.

Varieties of material

So, expanded polystyrene is a building material that can be classified as follows:

1. Bespressovy. Its structure consists of a large number of pore-granules, which have a heterogeneous structure. Their size varies between 5-10 mm. A feature of this type of product is that it has the highest level of water absorption.
2. Press. This material has the lowest heat transfer coefficient, since its granules are hermetically sealed.
3. This is the most common type of product, which is most often used for the insulation of buildings and structures. The pores in this material are also closed, however, they are smaller in size than in the previous case. This provides good thermal insulation properties.

In addition, there is also autoclave and autoclave-extrusion polystyrene foam.

Product Benefits

So, expanded polystyrene is a very common material that has the following advantages:

• Versatility. It is used in many even in the production of children's toys.
• Excellent qualities in terms of wind and noise protection of the premises.
• Durability.
• Remarkable thermal insulation properties.
• Neutrality to chemical reagents, resistance to aggressive agents.
• Good fire resistance (subject to good flame retardant treatment).
• Ability to perform its functions in a wide temperature range.
• Resistance to microbiological factors: rodents, insects, fungi, mold, decay.
• Maintaining original dimensions even under the influence of external factors.
• Relative ecological cleanliness.
• Low cost.
• Wide availability.
• Ease of installation and ease of use.
• Long term storage.

Product Disadvantages

Despite all the positive aspects, expanded polystyrene, the materials for the production of which are not natural, also has some negative qualities:

1. Increased brittleness if used incorrectly.
2. The product does not let steam through, which does not allow the room insulated with such material to “breathe”.
3. Expanded polystyrene practically does not burn, but it melts strongly, releasing toxic fumes.

Material Specifications

If there is a need to use expanded polystyrene, the dimensions and other characteristics of this product must be known in advance. So, the presented material has the following technical characteristics:

• Life time. Basically, manufacturers claim that with proper use, expanded polystyrene can last at least 50 years. Otherwise, its "life" will be significantly reduced.
• Suitable climatic regions: I - V.
• Thermal conductivity. This figure is very low, so the material is often used to insulate buildings and structures. The thermal conductivity coefficient is 0.037-0.043 W/mK.
• Moisture absorption. This figure is also very low. That is, polystyrene foam absorbs liquid very poorly. Its water permeability does not exceed 2-3% of the total volume. In addition, when in contact with liquid substances, the material is able to retain its shape and functionality well. This means that it can be used in those rooms in which there is an increased level of humidity, as well as for the treatment of surfaces that come into contact with water.
• Density and strength. If you need to choose expanded polystyrene, density is the parameter on which the effectiveness of insulation depends. This indicator varies between 0.015-0.05 kg / m3. Despite such small numbers, the compressive strength of the product is quite high.
• Noise absorption. In this regard, expanded polystyrene has high functionality. It is often used to build noise barriers on freeways.
• Flammability and temperature range. The burning period of the product does not exceed 4 seconds. In this case, the molten substance burns well. Therefore, when buying, you need to pay attention to the quality of the flame retardant treatment, which is mentioned on the packaging. It is practically not afraid of frost, therefore, it is possible to insulate with such material not only internal, but also external walls. Expanded polystyrene performs its functions well at a temperature of -60 - +80 degrees.

If it is necessary to insulate the house and expanded polystyrene is used for this, its dimensions can be as follows: width - 1-1.2 m, length - 0.8-1.4 m, thickness - 1-2 cm. large slabs, as there will be many small scraps. The most popular is polystyrene foam 100 mm long.

Applications

The presented material is used quite well due to its properties. and other parameters of which are already known, can be used in such areas of life:

• military industry. Here the product is used as a filler for helmets, shock-absorbing pads for knee and elbow pads.
• Food industry. Isometric packages are made from it, in which frozen foods are well stored.
• Construction. In this case, expanded polystyrene is used to insulate internal and external walls, basement floors, foundations and soil of underground structures from freezing. And from it, a permanent formwork for pouring the base is successfully built.
• Manufacturing of household appliances. Here the material is used only as an insulator for the walls of the refrigerator, although it is gradually being replaced by polyurethane foam.
• Interior decoration. From the presented material it is possible to produce furniture elements, as well as suspended ceilings, wall panels.
• Decorative design. A lot of beautiful elements are made from expanded polystyrene, which will make it possible to transform the interior.
• Toy production. In this case, the material is used as a filler, although it is not allowed in all countries.

Most often it is used as a thermal insulator. There are many reasons for this:

1. Reduced construction and installation costs.
2. Saves energy that is spent on heating the room.
3. The cost of heating equipment is reduced.
4. The size of the usable area increases, as the structural thickness of the walls decreases.
5. Increasing thermal comfort in the house.

Manufacturing features

The production of expanded polystyrene consists of several stages, the sequence and technology of which must not be violated. Otherwise, the quality of the product and its ability to perform its functions effectively will suffer.

In order for the polystyrene molecules to increase in size, they must be filled with a special gas. This happens by dissolving them in the melt of raw materials. During heating and boiling of the granular mixture, it swells. This process takes place in a special closed hopper, in the bottom of which there are holes. Through them, water vapor enters the bunker. In order to speed up the process, the granules can be mixed with a mechanical activator.

Further, through the unloading opening, the enlarged granules fall into an intermediate container, from which they are transferred to a special bunker for aging and drying. These processes are necessary to eliminate excess moisture from molecules, strengthen the outer walls of raw materials, and restore normal internal pressure. It is at this stage that the material already acquires the necessary parameters of compressive strength.

Drying of granules does not last long - only 5 minutes. The aging time can vary from 6 hours to a day. In this case, it is necessary to observe the required temperature - 22-28 degrees. Otherwise, the material may lose its properties.

Finished blocks are obtained using special block forms, into which prepared raw materials are poured. Naturally, the form must be preheated to the required temperature. Further, it is hermetically sealed. The baking process must be stopped on time, otherwise the finished material will turn out to be defective. The last step is cooling the plates. It lasts 12-72 hours. Further, in production, the plates are cut and trimmed.

Notable Manufacturers

If you need to purchase expanded polystyrene, Leroy is a chain of stores that has a wide selection of products. However, you need to decide on the manufacturer. The most popular are such brands:

1. "Penoplex". This material has an orange color and a rich variety of edges. It can be equipped with a tongue and groove, which facilitate the connection process, or be straight. Most often, this type of product is used for insulation of underground structures, as well as above-ground buildings. Often, various communications are insulated with such material. Such polystyrene foam can be used at temperatures from -50 to +80 degrees.
2. "Styrex". It is used to make sandwich panels. It is also used to protect the roadway from bulging soil.
3. Expanded polystyrene "Technoplex". This insulation is resistant to biological factors. It is widely used not only in private, but also in industrial construction. The plates are very durable, so they can be used to process any part of the structure.
4. "Primaplex". It is very popular, as it is quite cheap, and also has all the necessary characteristics. The product has a blue color, it is very easy to process. In addition, the material is not susceptible to the negative effects of water or negative temperatures, so it can be used for both internal and external insulation.
5. URSA. This material is environmentally friendly, good sound and thermal insulator. In addition, the product has good strength and low water absorption.

Is the material hazardous to health?

So, for more than one year, buyers have been arguing whether polystyrene foam can be used to insulate residential premises. The fact is that the presented product is synthetic, and is made from styrene. It, in turn, is not considered completely safe for human life and health.

But ... Expanded polystyrene ("Leroy Merlin" is the store where you can choose the option you need), does not irritate the skin or mucous membranes. Therefore, you can work with it without special protective equipment, which makes it very convenient to use.

Unlike other materials, expanded polystyrene is produced without the use of binders, which can eventually be released into the air, poisoning it. All granules in the product are glued together using conventional water vapor. The material does not contain any fibers in its composition, so it does not absorb dust.

Another advantage of the presented product is that it does not interact with living organisms. That is, mold and fungi that release dangerous spores do not multiply on it. That is, the air quality is not deteriorating.

The product does not dissolve in water and does not pollute it with synthetic additives that are used in the manufacture of other materials. Naturally, when burning, even the best polystyrene foam is capable of emitting gases. However, their toxicity is an order of magnitude less than that of PVC, wool, and even wood.

As for the combustion itself, when heated, the material turns into a liquid mass, which simply flows down the wall. However, even when heated, it will not even set fire to paper.

Features of using the product

So, the insulation of the house with polystyrene foam has some features. For example, when insulating walls inside a room, it is necessary to pay attention to places behind heating radiators. Here the partition can be somewhat thinner.

To fix the material, special glue or mastic, cement mortar, as well as special devices are used. The method of fixation can be combined. If the material will be used for external insulation, then it will have to be protected with a non-combustible cladding.

If you want to insulate a balcony or loggia with polystyrene foam, then you will have to equip a special frame in which the sheets will be placed. After fixing the material, it is sheathed with plywood. Only then can the surface finish be finished.

Window slopes can also be insulated with such a product. However, it is better to do this if the walls of the room are made of wood inside and brick outside. From the outside, the slopes are insulated only if during the construction of the building an external brick step was not provided.

The whole process of warming involves several stages:

• Surface preparation.
• Bonding sheets of material.
• Styrofoam binding and its additional fixing with mechanical devices.
• Reinforcing sheets with a special film.
• Finishing facing of the warmed base.

Features of using polystyrene foam for the floor

Very often the material presented is used to warm the base before laying the floor covering. can be of two types:

1. Plates with a layer of foil. They are more often stacked if installation of a warm floor system is foreseen. Therefore, special markings are applied to the surface of the plates even during their manufacture.
2. profile sheets. On their surface you can see low bosses. This greatly facilitates the installation of pipes. In addition, such material is equipped with a vapor barrier layer.

If the floor will be insulated with expanded polystyrene, then it is better to take into account some of the nuances:

• It is better to give preference to the extruded type of product.
• During laying, one should not forget about the presence of ventilation gaps between the plates and walls.
• If a laminate or parquet will be used to finish the floor, then it is better to build a crate on the surface of the base after insulation. When using carpet, it is better to level the surface with plywood.
• You need to lay the sheets back to back, as tightly as possible to each other.
• Base waterproofing must be present.

What is the difference between polystyrene foam and polystyrene foam - many people ask. I want to answer this question in the most accessible and detailed way, so that you understand the features and differences of these materials once and for all.

What is foam

As the name suggests, styrofoam is plastic foam. There are many plastics, so polystyrene can be understood as polyurethane foam, polyvinyl chloride foam, korbamido-formaldehyde, polystyrene foam, etc.

But it so happened that with the word "foam plastic" we represent a white cellular structure, which is often used not only in construction, but also in packaging, medical containers, and other industries. This substance is polystyrene foam.

Styrofoam refers to any foamed plastic. This is not the name of any particular material, but a general collective definition. Expanded polystyrene is a particular type of polystyrene. But among builders, these materials are often considered two different substances.

Polyfoam (polystyrene without pressing)

As we remember, polystyrene foam and polystyrene are essentially the same thing, but let's not forget about the power of habit and tradition. Bespressovy expanded polystyrene is the same foam that is white and with pimples.

The raw material for obtaining BSP is the same as for any other polystyrene foam - polystyrene. Due to such a different approach to the production of EPS, the result is quite a different product. These differences are clearly visible due to the known performance characteristics of these materials.

BSP is produced by adding granules with pentane or other low-boiling liquid to styrene, then the mixture is heated, the granules increase and the foam fills the mold. Then the granules are sintered in a special autoclave until the styrene polymerizes.

As a result, a white material is obtained, consisting of small bubbles glued together. 98% of the volume of the heat insulator is air.

This is a rather fragile material that crumbles and breaks.

Here are its specifications:

• Thermal conductivity: 0.335 – 0.41 W/m*K dry (+5 – +25);
• Density: 11 – 35 kg/m³;
• Vapor permeability: 0.012 mg/m*h*Pa;
• Compressive strength: 0.05 – 0.16 MPa;
• Bending strength: 0.07 – 0.25 MPa;
• Maximum board humidity: 1%;
• Water absorption for 24 days - 1%;
• Flammability class: G1;
• Self burning time: up to 3 seconds;
• Lifetime- 20 - 50 years.

As you can see, we have a rather brittle and fragile material in compression, which has a very low coefficient of thermal conductivity. If we talk about the combustibility of foam, we must remember that according to GOST 15588-2014, material with a combustibility class G1 is allowed for construction work, that is, it burns worse than wood.

For use in ventilated facades, any foam is undesirable. It is better to opt for mineral wool.

Low compressive strength makes even dense foam not the best choice for facades. It does not hold impact well, and as a result of unforeseen damage, it will be necessary to change the finish of the outer wall.

Extruded polystyrene foam

Let me remind you once again: is polystyrene foam plastic or not? Yes, this is foam, but its specific type. Among builders, expanded polystyrene is considered to be extruded polystyrene foam. It is also often called extrusion (EPS, XPS).

The whole difference lies in the way the material is produced.. It is made by extrusion: polystyrene granules are mixed with a foaming agent under pressure and at high temperature and squeezed out through an extruder, which gives the mass the desired shape. In addition, the material is obtained with cells, much more durable.

Let's look at the technical characteristics of EPPS:

• Thermal conductivity: 0.028 – 0.039 W/m*K;
• Density: 26 – 45 kg/m³;
• Vapor permeability: 0.18 – 0.02 mg/m*h*Pa;
• Compressive strength at deformation by 10%: 0.25 – 0.47 N/mm²:
• Bending strength: 0.4 – 0.96 N/mm²:
• Water absorption in 24 hours, in % by volume: 0.2;
• Flammability group: G1;
• Ability to self-sustain combustion: no more than 2 seconds;
• Durability: up to 50 years.

Production technologies can change many parameters. We see that the extrusion method produces a more perfect insulation, while using completely identical raw materials. Now it is much easier to answer which is better, PSB or EPPS?

Extrusion PPS also has its drawbacks. Its price is noticeably higher than that of polystyrene, it weighs more and has a lower vapor permeability. And this negatively affects the microclimate in the room (or requires good ventilation).

We determine the winner

I talked about the most relevant properties and characteristics of two types of insulation: BSP and EPS. Now you need to decide what to choose - foam or modern XPS?

The consumer is primarily interested in what is warmer, and extruded polystyrene foam wins here. On the other hand, cost is an important parameter, and in this category, the undisputed winner is foam.

An important parameter is the possibility of mounting the material with your own hands, without hiring craftsmen. The installation instructions for both heaters are quite simple and do not require special skills, so there is a draw here.

Let's add to our comparison the following nuances:

1. Extruded PPS is much less afraid of moisture, which allows it to be used in wet rooms or for insulation of foundations.
2. Sheets are much stronger, they can be used as fixed formwork.
3. Plate geometry is much more even which makes it easier to work with the material.
4. XPS is much easier and smoother to cut.
5. There are almost always locks on the ends, which excludes "cold bridges".

Such a set of arguments and facts gives me the right to make a choice in the direction of EPPS. This is my personal opinion, which can be discussed in the comments to the article.

Conclusion

After a detailed examination of polystyrene foam insulation, you no longer have the question “How does extruded PPS differ from polystyrene?”. You can easily choose the option that is right for you.

And after watching the video in this article, you can give good advice to your neighbors. Questions and comments are welcome in the comments.

In this article: the history of the discovery of polystyrene; production technologies; scopes of expanded polystyrene; application in construction, GOSTs; properties and characteristics; environmental friendliness, durability and fire safety - is this insulation so safe; what does the term "self-extinguishing polystyrene foam" really mean; how to choose polystyrene foam

The cost of heating our homes during the cold season is very significant, and the ever-increasing cost of energy carriers increases these costs year by year. But did you know that in cold weather, heat literally disappears 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 per square meter, while only 40 gigacalories are lost per square meter of housing in Germany or the USA. It turns out that homeowners actually pay for heating the street, and not their homes at all ... The problem of heat loss can be solved by insulating the walls of the building from the outside with polystyrene foam plates - 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 obtained styrene. Having experimented a little with his discovery, the pharmacist found that the oily substance he received compacted itself, turning into a kind of jelly. Simon did not see a practical goal in the discovery of styrene - he called the jelly-like styrene styrene oxide and stopped further research.

In 1845, the chemists Blith and von Hoffmann became interested in styrene - an Englishman and a German conducted their own research, establishing that this substance becomes jelly-like without oxygen. The chemists named the gel-like styrene they obtained as metastyrene. 21 years later, the French chemist Marceline Berthelot gave the exact name for the process of compacting styrene - polymerization.

Hermann Staudinger, 1935

In the 20s of the last century, the German chemist Hermann Staudinger made a landmark 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 synthesis of styrene 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 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 ​​\u200b\u200bthis invention belongs to the chemical engineer Fritz Stäsny. On the basis of this patent, in 1951, BASF began the industrial production of a thermal insulator under the brand name Styropor, which is still produced today.

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

• Polystyrene granules are poured into the pre-expander hopper, where they are inflated and become spherical. To obtain a heat insulator of lower density, the foaming operation is repeated several times, each time reaching an increasing size of the balls 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 beads are from 12 to 24 hours. During this period, the pressure inside them stabilizes, and during the production by the method of suspension polymerization, they are also dried;
• upon completion of a given number of foaming operations and having endured 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 foam granules stick together with each other, retaining their shape after cooling and removal from the mold;
• at the last stage, polystyrene blocks, often of impressive size, are cut to size. But first, the block from the molding unit is placed in intermediate storage, where it is kept for about 24 hours. The fact is that under the influence of steam, the polystyrene foam block gains excess moisture, and it will not work in any way to perform even cutting in the wet state of polystyrene foam, because. cracks cannot be avoided. After drying, the styrofoam 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 foaming stage, styrene granules are poured into reactor-autoclaves 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 the maximum 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 passes through the drying stage. The main advantages of this technology are constant mixing of 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 bulk 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 agitators-reactors connected in series with each other, at a temperature from initial 80 to final 220 ° C, polystyrene granules foam. Polymerization is considered to have taken place and completed if from 80 to 90% of the original styrene is melted. When creating a vacuum in the last column-type reactor, unreacted styrene is eliminated, then flame 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 in the next backfill. It is extremely difficult to bring the process of polymerization of raw materials to obtain more than 90% of foamed polystyrene using this technology, because the reaction rate is quite high, and there is no possibility of heat removal here.

The production of foamed polystyrene by the suspension polymerization method is more common in Russia and the CIS, in the countries of the West and America, mass polymerization technology prevails, which makes it possible to obtain a heat insulator with higher characteristics in terms of density, flexibility, clarity of boundaries and color, not to mention a smaller percentage of waste.

The technology for producing extruded (extrusive) expanded polystyrene is generally similar to the polymerization technology. The difference lies in forcing the melt with foaming agents introduced into its composition through a press extruder, resulting in a heat insulator with cells up to 0.2 mm in diameter. It is the small cell size 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 processing and processing, low cost - thanks to these characteristics, expanded polystyrene is widely used in various areas of our life. Most often, this material is used for: packaging of various goods and equipment; isothermal food packaging; production of disposable tableware; energy absorbers in the automotive industry; rescue boats; volumetric outdoor advertising, etc.

The absence of the threat of dusting - the main positive difference between expanded polystyrene and mineral wool - makes it possible to use 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, high-density polystyrene grades are used - from 35 kg / m 3 and above. This material is also used for thermal insulation of the railway track, effectively preventing the rails from warping and sinking on unstable soils.

One of the first to use polystyrene for building insulation was the American Hoot Heddock. According to him, the idea of ​​\u200b\u200bthermal insulation of houses arose by chance - Huth ordered a cup of hot coffee in a cafe and suddenly noticed that the hot liquid in a disposable polystyrene cup did not burn his fingers at all. Having conducted an experiment in 1984 - having built a house in Alaska and insulated it with foam plastic - he was 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 EU countries, 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 outer (outer) side, they are covered with a layer of plaster on top.

As noted by European architects, the use of expanded polystyrene in facade insulation reduces energy costs for heating three times.

Plates and blocks made of extruded polystyrene foam are used as a fixed 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 system of screeds, reinforcement reinforcement is placed in the gap between the plates and concrete is poured. A variety of ready-made polystyrene blocks allows you to build facades of complex architecture. A protective coating must be applied to the walls assembled from blocks of extruded polystyrene foam and filled with concrete - from the outside it can be facing bricks or cement-sand plaster, from the inside two layers of drywall with docking "in a run" or a layer of plaster. An important condition for the formwork made of expanded polystyrene: the density of this material in the formwork blocks must be at least 35 kg / m 3.

Glue for expanded polystyrene should not contain in its composition organic solvents that destroy polystyrene. It is most safe to use cement-based adhesives packed in 25 kg kraft bags and mixed with water - the 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% of the contact area) in order to exclude air sinuses that act as cold bridges and accumulate condensate.

Thermal conductivity

The high thermal insulation properties of expanded polystyrene are explained by its structure, formed by many balls soldered together, in turn consisting of many cells with air enclosed in them. And since the air inside the cells is not able to move, it is he who acts as a heat insulator - a motionless 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 polystyrene foam with a density of 45 kg / m 3, the thermal conductivity coefficient is 0.030 W / m·K. Operating temperatures at which expanded polystyrene retains its properties - from - 50 to + 75 ° C.

Water absorption and vapor permeability

If we compare extruded polystyrene foam with foam plastic 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 foamed polystyrene material cannot pass steam? The reason for the vapor permeability of extruded polystyrene foam, which is denser compared to 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: polystyrene 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 greater 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, while polystyrene 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 the foam. Therefore, the production and use of the latter is increasingly declining - polystyrene is being replaced by a more durable and modern heat insulator, which is polystyrene foam obtained by forcing through a press extruder.

Interaction with chemical and organic products

Expanded polystyrene is not affected by: mortars based on gypsum, cement, anhydrite or lime; bituminous resins, caustic soda, soap and salt solutions, mineral fertilizers, ground water and emulsions used in 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 petroleum products.

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

Sound conductivity

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

Biological stability

It is impossible for mold to survive on the surfaces of polystyrene foam boards - these are the results of laboratory tests conducted in the USA in 2004 by order of American manufacturers of polystyrene foam.

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 performance properties for many years. Outwardly, it looks like this - the exclusion of freon from the technological process does not harm the ozone layer, the introduction of flame retardants makes polystyrene foam non-combustible, and laboratory tests characterize durability with dozens of freeze and thaw cycles. However, a closer examination of polystyrene foam shows a slightly different picture ...

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

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

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

So what gives styrofoam manufacturers the ability to 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 combustible, 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 methodology for assessing toxicity, wood materials are the most dangerous material - they quickly burn out 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, which are incomparable, for example, when comparing the toxicity of combustion products of wood and polystyrene. The same is true with the calculation of toxicity by the chemical method ...

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

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

Another classic move that allegedly demonstrates the incombustibility of polystyrene: the plate is suspended in the air, the flame of the burner is directed at it - so the part of the plate 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 rigid non-combustible surface, then the melt drops formed during the combustion of the material will spread the heat and open flame over the entire area of ​​​​the plate, which will burn out completely!

The smoke generation coefficient for polystyrene foam that does not contain flame retardants is 1,048 m 2 / kg, but for self-extinguishing polystyrene foam with flame retardants introduced into its composition, this figure is higher - 1,219 m 2 / kg! For comparison: the smoke emission 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 ​​\u200b\u200bof smoke generation do not explain anything, I will give such data - if the smoke content in the room is more than 500 m 2 / kg, then absolutely nothing will be visible at arm's length.

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

Styrofoam durability

When buying a really high-quality heat-insulating 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 in reality, these conditions are never 100% met - the lack of professionalism of installers, attempts by customers to reduce costs, errors in calculations and hope "at random".

A classic miscalculation is the bet on the thickness of expanded polystyrene - they say, if you mount plates of 30 cm thickness, then the heat-insulating effect will increase significantly with a simultaneous increase in the service life of the material. In fact, with increasing thickness, the service life of polystyrene thermal insulation will be reduced, because. significant temperature differences will cause deformation and shrinkage, forming cracks and a decrease in the area of ​​​​direct contact of the expanded polystyrene plates with the insulated surface, forming extensive air sinuses. In the EU countries, the thickness of expanded polystyrene used for facade insulation cannot exceed 3.5 cm - this requirement, in addition to issues of durability of thermal insulation, is related to fire safety, because the thinner the layer of expanded polystyrene, the less combustion products will be released to them during a fire.

In order to reduce the risk of fire, manufacturers introduce flame retardants into the composition of polystyrene, as a rule, this is hexabromocyclododexane. In Russia, expanded polystyrene with flame 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 flame retardant.

The question arises - so what does the letter "C" mean? And it means that this polystyrene foam will not spontaneously ignite when the temperature rises, nothing more. According to the degree of flammability, self-extinguishing expanded polystyrene is assigned class G2, but it is worth considering that over the course of its operation, 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.

Styrofoam selection criteria

Cheapness, high thermal insulation qualities have made materials based on polystyrene extremely popular in the construction market. And the increase in demand has led to the emergence of many enterprises vying with each other offering products of their own production, declaring its exceptional quality.

Be careful when choosing the brand of expanded polystyrene - as a facade insulation, it would be correct to choose PSB-S (self-extinguishing expanded polystyrene) not lower than the 40th brand. At the same time, it is worth considering the nuance - the manufacturer, within the framework of the specifications developed by him, produces PSB-S-40 with a density in the range from 28 to 40 kg / m 3, and not at all 40 kg / m 3, as an ignorant buyer suggests, focusing on the number in the brand . It is quite natural that it is more profitable for a manufacturer to produce brand 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 grades below the 25th in construction - the density of such expanded polystyrene will actually correspond to packing foam, unsuitable for facade insulation due to the rapid loss of performance.

It would be nice to find out what technological process for producing 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 the production process, the highest density of polystyrene will not exceed 17 kg/m 3 .

You can find out the quality of polystyrene by breaking it - a 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 in high-quality extruded polystyrene foam will show polyhedrons of the same size that form 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 expanded polystyrene manufacturers is sufficient to produce a truly high-quality product.

At the end

In the presence of negative characteristics in terms of combustibility and combustion products, expanded polystyrene is one of the best and, at the same time, inexpensive heat insulators. By enclosing a polystyrene slab between two layers of cement plaster, you can get high-quality thermal insulation of buildings and premises - it makes no sense 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 the same 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 slightest area of ​​\u200b\u200bcontact of expanded polystyrene with the atmosphere and solar ultraviolet will lead to its rapid destruction.

Is it worth it to insulate the interior with this material - it’s not worth it, despite all the assurances of the manufacturers. They will give guarantees, but what good will that do in the event of a fire...

Abdyuzhanov Rustam, rmnt.ru

Styrofoam- building insulation material obtained by foaming polystyrene.

This material comes in different colors, but mostly its color is white. The main composition is: polystyrene with additives - 2% and gas - 98%.

General information about polystyrene foam

Expanded polystyrene consists of:

• main component (polystyrene);
• blowing agent;
• dye;
• plasticizer and other additives.

The main component in most cases is polystyrene. May also be used:

• polydichlorostyrene;
• polymonochlorostyrene;
• copolymer with acrylonitrile;
• copolymer with butadiene.

Foaming agents for the manufacture of expanded polystyrene use the following:

• pentane, C 5 H 12 ;
• petroleum ether;
• dichloromethane CH 2 Cl 2 ;
• isopentane.

The main characteristics of expanded polystyrene, scope, advantages and disadvantages

Expanded polystyrene is a very light material that has low thermal conductivity and vapor permeability. Due to this composition (only 2% of raw materials), it is considered, in comparison with analogues, a relatively cheap material.

Basically, expanded polystyrene is intended for thermal insulation of enclosing structures of buildings and structures. For example, in Europe, 60% of the total expanded polystyrene produced is used in the construction industry to insulate building envelopes.

Expanded polystyrene is produced in the form of sheets 1000x1000 mm; 1000x1200 mm; 2000x1000 mm; 2000x1200 mm.

Sheet thickness 20, 30, 40, 50, 100 mm. Other thicknesses can also be made to order.

Production of expanded polystyrene and its varieties

Polystyrene particles are bombarded with pure hydrocarbon (pentane) and heated steam, resulting in a chemical reaction of foaming and expansion. Thus, polystyrene increases in volume by 40 ... 50 times, filling the form. Polystyrene itself, as a raw material, is made from oil.

It is interesting! According to regulatory documents, when comparing the thermal properties of expanded polystyrene and other building materials, a 10 cm thick expanded polystyrene wall is equivalent in thermal conductivity to a wall made of:

• reinforced concrete 4.8 m thick;
• solid clay bricks 1.75 m thick;
• hollow clay brick 1.45 m thick;
• silicate solid brick 1.9 m thick;
• expanded clay concrete 0.5 m thick;
• wood 0.35 m thick.

There are such types of polystyrene foam:

1. Extruded polystyrene foam (PS)
2. Bespressovy expanded polystyrene (PSB)
3. Extruded polystyrene foam (EPS)
4. Autoclaved polystyrene foam
5. Autoclave-extrusion polystyrene foam

Varieties of expanded polystyrene differ from each other only in different additives, such as flame retardants, plasticizers, steam generators, etc. The use of certain additives and their amount causes significant differences in physical and mechanical properties.

Consider some types of polystyrene foam

Pressed polystyrene foam. The very word "pressing" in the name of expanded polystyrene speaks of the method of its production. Pressing is performed in order to obtain a denser and more durable material. Extruded polystyrene foam in terms of thermal insulation properties practically does not differ from non-pressed one.

Marked with letters PS(for example, PS-1, PS-4). widespread PS did not receive it, since the technological process of production is more complex than that of the non-pressed one (the cost increases, but the effect of this is insignificant).

This is the most common type of polystyrene foam. Such material has a number of advantages and disadvantages. The marking of non-pressed polystyrene foam is indicated - PSB. The cost of non-pressure expanded polystyrene is lower compared to PS, since the technology for obtaining it is much simpler.

According to GOST-15588-86 "Polystyrene foam plates specifications", polystyrene foam plates are divided into the following grades - 15, 25, 35, 50 .

AT tab. one data of the main characteristics are given, according to which the brand of polystyrene foam boards is determined. I would like to draw attention to one nuance - the upper limit of the density of the material appears in the brand of foam plastic, and not the actual density value. The actual value of the density of the foam is approximately the average value of the limit specified in tab. one.

The main characteristics of expanded polystyrene depending on its density grade (DSTU B.V.2.7.-8-94), see tab. one.

Table 1

Characteristics of non-pressed polystyrene foam

Note: the letter "C" in the brand of expanded polystyrene means - self-extinguishing, i.e. during manufacture, flame retardants are added to the material, with the help of which, in the absence of direct exposure to fire, the material decays and stops burning (extinguishes and does not support combustion).

Where is polystyrene used?

Depending on the density of expanded polystyrene, it is used:

PSB S-15 - used for insulation and sound insulation of structures that are not subjected to mechanical stress. Also used for insulation of pitched roofs. It is unacceptable to use for the insulation of the facades of capital residential buildings and for the implementation of the inner layer of the outer walls.

PSB S-25 - used for insulation of walls, floors, roofs of buildings and structures (most used). Can be used as soundproofing.

PSB S-35 - used for the manufacture of sandwich panels, floor insulation and flat roofs.

PSB S-50 - for insulation of warehouse industrial refrigeration rooms, for insulation of foundations, basements, floors, roofs, especially where there is high humidity.

Extruded (extruded) expanded polystyrene (EPS)

Extruded polystyrene foam (EPS) or XPS) - compared to others, it has a very fine structure of closed pores and voids with a diameter of 0.1 ... 0.2 mm. The material is obtained by extrusion - polystyrene is melted at a high temperature, then a foaming agent is added and extruded (extruded) into a mold under pressure.

Such polystyrene foam has increased compressive strength at a density of only 25 ... 45 kg / m 3; the material has a low thermal conductivity of 0.029…0.034 W/(m °C) and is practically waterproof (water absorption is 0.2…0.4%). Due to the fact that extruded polystyrene foam is very dense, its vapor permeability is very low - 0.013 Mg / (m h Pa) - 4 times lower than that of PSB grade expanded polystyrene.

EPPS has a very high degree of flammability - flammability class G3, G4. Its durability is over 60…80 years. Due to its shortcomings (high flammability, low vapor permeability), it is used mainly for warming underground structures - warming foundations, basements, basements. Building facades are also insulated.

They produce extruded polystyrene foam of the following grades: XPS 25, XPS 30, XPS 35 and XPS 45(the figure indicates the density of the material in kg / m 3).

Benefits of Styrofoam

1. Durability - does not rot, does not form cracks, is not food for rodents and insects. After a long period of operation (10 ... 50 years) it retains all its basic properties.
2. Very low water absorption (non-hygroscopic) - 0.5 ... 4% by volume. Humidity practically does not affect the thermal conductivity of dense polystyrene foam.
3. Lightweight material, easy to use, does not require serious skills when working with it.
4. Low cost and good payback. When insulating a house with polystyrene foam, the effect is immediately felt - the cost of heating and air conditioning is significantly reduced (by about 3 ... 4 times).

Disadvantages of Styrofoam

Expanded polystyrene has a number of disadvantages:

1. Ultraviolet rays lead to destructive changes and aging of the material with its subsequent destruction.
2. The following substances have a destructive effect: acetone, gasoline, paint thinner, kerosene, turpentine, toluene.
3. Styrofoam is not food for insects and rodents, but they can easily make their way to food in it. Therefore, additional protection of this material is required.
4. Expanded polystyrene is a fireproof material. Ordinary non-certified expanded polystyrene is a highly flammable material (ignition temperature 210 ... 440 ° C) and, when burned, emits smoke and toxic substances (phosgene, hydrogen bromide), which are dangerous to human life and health. Not certified (or not modified) is forbidden to be used for thermal insulation of buildings. For the safe operation of this material, various flame retardants are used in its manufacture, which provide self-extinguishing and fire safety of the product. To reduce the likelihood of fire, polystyrene foam bubbles are filled not with air, but with carbon dioxide. According to DBN V.1.1-7-2002 "Fire Safety of Construction Objects", such certified expanded polystyrene belongs to the combustibility group G1.
5. In very porous expanded polystyrene (grades with low density), water vapor can pass through the material and condense in it, thereby increasing its thermal conductivity by 5 ... 10%. And at negative temperatures, the resulting condensate freezes and thereby destroys the material.

Konev Alexander Anatolievich