Polyfoam extruded: technical characteristics, thickness, density, thermal conductivity

The modern construction market today is just full of a lot of thermal insulation materials. They differ not only in the features of the manufacturing technology, but also in their properties, as well as in their designation. However, one of the most popular is extruded expanded polystyrene, which will be discussed below. It can be used not only for thermal insulation, but also for protecting the building from external noise. To increase the efficiency, you can stack the material in several layers.

Description

EP has unique heat-insulating qualities, and in appearance resembles polystyrene, which is used today for insulation of the facade. Specifications significantly exceed the performance of traditional foam. It is made from polystyrene pellets, which are melted under the influence of high temperature and form a viscous state. Under high pressure, carbon or freon is injected into the chamber, each of which is a foaming agent. The resulting mass is extruded through the extruder and forms a certain shape.

For reference

This technology allows the creation of extruded expanded polystyrene, which has a cellular closed structure and resists penetration of heat and moisture. It is resistant to aggressive media such as alkali and acids, and it can be used at extremely low temperatures, which can reach -50 ° C. If we are talking about the highest possible temperature, then it is kept at around +70 ° C.

Thickness of material

If you decide to purchase extruded polystyrene foam, you should know about its thickness. At different companies this parameter is different, therefore on sale it is possible to find plates, starting from 20 mm and ending up to 20 cm. This raises the question of what thickness to choose for carrying out those or other works. To do this, you need to know what is the resistance to the heat transfer of materials from which objects are built that need to be insulated.

There are established norms and rules that indicate the nominal resistance of heat transfer in certain regions. For example, in the center of Moscow, wall resistance will be 4.15 m ² ° C / W, while for southern regions this figure will be a maximum of 2.8 m ² ° C / W.

Once you determine the norm of the region, you should calculate the resistance of the material and take it away from the norm. The resulting value will indicate the resistance of expanded polystyrene. If you have the results, then according to the table you can determine the required thickness of thermal insulation.

Density of material

Polyfoam extruded, whose density is from 28 to 40 kg / m ³ , is represented by the PBS-S-40 brand. Sometimes the manufacturer tries to mislead the buyer, because the production of expanded polystyrene of lower density will take less money. Therefore, one should not rely only on the number in the brand name, it is necessary to inquire about the technical characteristics that should be indicated in the certificates.

It will be great if you are told how the material is made. If the density is 35 kg / m ³ , then this is extrusion. The usual way is to achieve a density that does not exceed 17 kg / m ³ .

Thermal conductivity of EP

Extruded polystyrene, the thickness of which was mentioned above, should be selected by the consumer not only from these data, but also taking into account the thermal conductivity. The insulant described in the article is a huge quantity of air bubbles, which are separated by thin shells of polystyrene. In this case, the ratio is: 98% air and 2% polystyrene. The result is a semblance of solid foam. The air is enclosed inside the bubbles, due to this the material keeps the heat. The air layer without movement is an excellent heat insulator.

If you compare with mineral wool, the coefficient of its thermal conductivity will be higher. It will be from 0.028 to 0.034 W / (m · K). The more dense the foam is, the greater the value of the coefficient of thermal conductivity. Thus, for an extruded foam having a density of 45 kg / m ³ , this parameter is 0.03 W / (m · K). It should be taken into account that the ambient temperature should not be above +75 ° C and below -50 ° C.

Basic properties

Extruded polystyrene, the thermal conductivity of which was mentioned above, has certain properties, among which almost complete absence of water absorption and low thermal conductivity. Even if the plate is completely immersed in water for 10 days, the cells will not pass through the moisture, since they are isolated, only the side open honeycombs will be filled. We talked about the thermal conductivity above, we should also mention that this parameter is much smaller in comparison with other thermal insulation materials. Plasticity is also not so high, but fragility is impressive, especially if you draw a parallel with foamed polystyrene.

The material has the ability to transmit light, and its compressive strength is high enough. Thermal insulation is not putrefied and has a high frost resistance. Extruded foam extends freely:

• Acids;
• water;
• Caustic alkalis;
• Oils;
• Bleach;
• Saline solutions;
• Dyes;
• Alcohol;
• Hydrocarbon;
• Cement;
• Acetylene;
• Paraffin;
• Propane;
• Butane.

It is impossible not to mention also the safety for man.

Specifications

Extruded polystyrene, the characteristics of which have been partially mentioned above, have a minimum water absorption, which varies between 0.2 and 0.4%. The weight is small enough and can vary from 25 to 45 kg / m ³ . Among the disadvantages can be identified a poor vapor permeability, which is 5 times lower compared to traditional foam. This value is 0.013 Mg / (m * h * Pa). That raises requirements to ventilating systems of the house which will be warmed by extrusion polystyrene foam.

Extruded polystyrene, the technical characteristics of which will be of interest to the consumer, has one more drawback, which is expressed in high combustibility. The material belongs to the class G3-G4, but already today many manufacturers use special additives that have allowed to achieve almost non-combustible characteristics. Therefore, this thermal insulation can sometimes be attributed to classes T1 and B1.

Nevertheless, if you look at the sanitary norms and rules, it can be emphasized that extrusion plates that have a high degree of flammability can be used in building structures. If higher fire safety requirements are imposed on the building, then extruded polystyrene foam, which belongs to the G3 flammability group, should be used.

Conclusion

Recently, the federal law on combustible heat-insulating materials has been issued, it contains information on the toxicity of combustion products. For high-quality expanded polystyrene, the toxicity does not exceed T2, which indicates that this insulation is moderately hazardous. This indicator is inherent in materials made of wood, for example, parquet. The service life is comparable with the service life of the building, and for quality manufacturers this indicator reaches 40 years.