Thermal conductivity of expanded polystyrene, features and thickness of material

Thermal conductivity of expanded polystyrene is one of the important characteristics that not only professionals, but also ordinary consumers are interested in. This material is also called polystyrene and is a thermal insulation, which consists of 98% air. It is enclosed in foam polystyrene cells.

The structure is completely safe for health, therefore the material used to make food packaging is used. It can be easily processed, found its wide distribution in the field of construction, and also has a low cost.

What you need to know about the thermal conductivity of expanded polystyrene

The thermal conductivity of expanded polystyrene is rather low, because the air that is the basis of the material also has such characteristics. Therefore, the described insulation parameter varies from 0.037 to 0.043 W / mK, with respect to air, this characteristic is equal to 0.027W / mK.

Expanded polystyrene is manufactured in accordance with GOST 15588-86 and is characterized by excellent energy saving, extended service life, it can reduce heating costs and protect from frost. Such properties are preserved even under the influence of low temperatures and high humidity, therefore it is possible to use expanded polystyrene in the conditions of storage facilities, as well as in the construction of refrigeration equipment.

The thermal conductivity of expanded polystyrene is low, so this material can be used not only for interior, but also for exterior decoration. However, this characteristic will vary with density. The higher it is, the more styrene content, the worse the styrofoam will retain heat. For example, if we are talking about extruded polystyrene foam, its thermal conductivity will be 0.028W / mK, since the styrene granules are in this case in the structure of a single sheet, and there are no gaps between them.

Comparison of thermal conductivity in different brands

For comparison, we can consider several grades of expanded polystyrene, the density and thermal conductivity in which they differ. The density of PSB-C15 does not reach 15 kg / m3, while the thermal conductivity is a limit of 0.07-0.08 W / mK. As for the brand PSB-C35, its density is equal to the limit of 25.1 to 35 kg / m ³ , while the thermal conductivity is 0.038 W / mK. On sale, one can also find extrusion foamed polystyrene. For grade 35, the density varies from 33 to 38, while the thermal conductivity is 0.03.

If before you mark 45, the first parameter will vary from 38.1 to 45, while the second will be 0.032. The thermal conductivity of expanded polystyrene is much lower than that characteristic of other materials. For example, expanded clay concrete with a density of 1200 kg / m ³ has a thermal conductivity of 0.58.

Comparison of the thermal conductivity of expanded polystyrene with other materials

In many areas of industry and construction, expanded polystyrene is used today. The thermal conductivity, the comparison of which will be mentioned below, is rather low in this case. But in mineral wool this characteristic varies from 0.07 to 0.08 W / mK. As for concrete, the thermal conductivity of the concrete will be 1.30, while that of reinforced concrete - 2.04.

Claydite concrete and foam concrete are characterized by a thermal conductivity of 0.58 and 0.37, respectively. For expanded polystyrene, for comparison, the thermal conductivity is 0.028W / mK. Thermal conductivity of expanded polystyrene and expanded polystyrene is also often compared. In the first case, this value will be 0.07, if it is a plate.

Main features: safety, soundproofness and wind protection characteristics

Styrofoam is safe, but you can use it again. At the same time, no harmful substances will be released into the environment. According to the research, dangerous styrene was not found in the building structures of expanded polystyrene. As for soundproofing and wind protection, when using expanded polystyrene there is no need to additionally use materials that increase windproof functions and soundproofing.

If the sound attenuating capabilities need to be strengthened, the thickness of the material layer must be increased. The thermal conductivity of extruded polystyrene is already known to you, but this is not the only characteristic that you should know about before purchasing this material. For example, expanded polystyrene is not hygroscopic, therefore it does not absorb water and moisture, does not swell and does not deform, and also does not dissolve in the liquid. If you put the expanded polystyrene in water, only 3% of the weight of the board will penetrate the structure, while the properties of the material will remain unchanged.

Steam and water come out of the expanded polystyrene quite easily, so care must be taken to avoid condensation. For this, the design rules are observed. Moisture resistance of expanded polystyrene allows it to be used when the basement is insulated, where material is inevitable to contact the ground.

Additional features: biological and chemical inertness

Heat insulation foam polystyrene, the thermal conductivity of which was mentioned above, is resistant to chemical and biological factors. Properties of the material will be preserved, even if its structure will be affected:

• Soap solutions;
• Acids;
• Salt solutions of the type of sea water;
• Bleaching agents;
• ammonia;
• gypsum;
• Water-soluble paints;
• Glutinous solutions;
• lime;
• cement.

As for acids, nitric and concentrated acetic acids should not be affected by expanded polystyrene. During the installation, access to the rodent and termite material should be excluded, since they can cause damage to the structure. Under the influence of concrete solutions, the material can partially decompose, as under the influence of organic solvents. Stability can be determined by the ratio of open and closed pores, which depends on the brand and type of insulation.

Fire resistance of expanded polystyrene

The coefficient of thermal conductivity of expanded polystyrene has been mentioned above, but it is also important to know about the fire hazard of a material that is combustible, but has good fire resistance, because the autoignition temperature is 4910 ° C. If you compare this indicator with wood, then it is 1.8 times higher, because for a tree it will be enough only 2600 ° C.

The flammability class and the ability to generate heat

If the fire is absent for 4 seconds, then the material will self-extinguish. During the combustion, the insulation will generate heat in the volume of 1000 MJ / m ³ , as for wood, this index varies from 7000 to 8000 MJ / m ³ , which indicates that the temperature will be much lower when burning polystyrene foam. On sale today you can find a self-extinguishing foam polystyrene, which is produced with the addition of flame retardants. But over time this effect is lost, and the material that belonged to the G2 flammability group will eventually fall into the G4 class.

Thickness of expanded polystyrene

Styrofoam, heat conductivity, the thickness of which you should be aware of, if you plan to purchase this insulation, is produced today by different manufacturers. The sheet can be limited in thickness from 20 mm to 20 cm. At the same time, many consumers are wondering which sheet is best to choose. To determine this value, you need to ask what is the resistance to heat transfer. Here everything will depend on the region of the country. For example, in the center of Moscow, the wall resistance should be 4.15 m ² ° C / W, as for the southern regions, then 2.8 m ² ° C / W will be enough here.