The thermal conductivity of expanded polystyrene is one of the important characteristics that is of interest not only to professionals, but also to ordinary consumers. This material is also called polystyrene and is a thermal insulation, which is 98% air. It is enclosed in expanded polystyrene cells.
The structure is completely safe for health, therefore, material is used to make food packaging. It is easy to process, 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 quite low, because the air, which is the basis of the material, also has such characteristics. Therefore, the described insulation parameter varies from 0.037 to 0.043 W / mK, as for air, this characteristic is equal to 0.027 W / mK.
Expanded polystyrene is manufactured in accordance with GOST 15588-86 and is characterized by excellent energy saving, extended service life, is able to reduce heating costs and protect against freezing. Such properties are preserved even when exposed to low temperatures and high humidity, so you can use expanded polystyrene in warehouse conditions, 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 internal but also for external decoration. However, this characteristic will vary with density. The higher it is, the higher the styrene content, the worse the polystyrene foam will retain heat. For example, if we are talking about extruded polystyrene foam, then its thermal conductivity will be 0.028 W / mK, because styrene granules in this case are in the structure of the whole sheet, and there are no gaps between them.
Comparison of thermal conductivity of different brands
For comparison, we can consider several grades of polystyrene foam, the density and thermal conductivity of which differ. The density of PSB-C15 does not reach 15 kg / m 3 , while the thermal conductivity is the limit of 0.07-0.08 W / mK. As for the PSB-S35 brand, its density is equal to the limit from 25.1 to 35 kg / m 3 , while the thermal conductivity is 0.038 W / mK. On sale you can also find extruded expanded polystyrene. At grade 35, the density varies from 33 to 38, while the thermal conductivity is 0.03.
If you have a mark of 45, then the first parameter will vary from 38.1 to 45, while the second will be equal to 0.032. The thermal conductivity of expanded polystyrene is much lower compared to this characteristic of other materials. For example, expanded clay at a density of 1200 kg / m 3 has a thermal conductivity of 0.58.
Comparison of thermal conductivity of expanded polystyrene with other materials
In many areas of industry and construction, polystyrene foam is used today. The thermal conductivity, a comparison of which will be mentioned below, is rather low in this case. But for mineral wool, this characteristic varies from 0.07 to 0.08 W / mK. As for concrete, its thermal conductivity will be 1.30, while that of reinforced concrete - 2.04.
Expanded clay and foam concrete has a thermal conductivity of 0.58 and 0.37, respectively. In polystyrene foam, for comparison, the thermal conductivity is 0.028 W / mK. The thermal conductivity of polystyrene foam and polystyrene foam is also quite often compared. In the first case, this value will be 0.07, if we are talking about plates.
Key Features: Safety, Soundproof and Windproof
Styrofoam is safe and reusable. In this case, harmful substances will not be released into the environment. According to studies, no dangerous styrene was found in polystyrene foam building structures. As for soundproofing and wind protection, when using expanded polystyrene there is no need to additionally apply materials that increase windproof functions and sound insulation.
If the noise absorption capacity needs to be enhanced, then the thickness of the material layer should be increased. You already know the thermal conductivity of extruded polystyrene foam , but this is not the only characteristic that you should know about before purchasing this material. For example, polystyrene foam is not hygroscopic, therefore it does not absorb water and moisture, does not swell and does not deform, and also does not dissolve in a liquid. If polystyrene foam is placed in water, then only 3% of the weight of the plate will penetrate into the structure, while the properties of the material will remain unchanged.
Steam and water quite easily exit polystyrene foam, so care must be taken to prevent the formation of condensate. For this, design rules are followed. The moisture resistance of polystyrene foam allows you to use it when warming the foundation, where contact of the material with the soil is inevitable.
Additional features: biological and chemical inertness
Insulation polystyrene foam, the thermal conductivity of which was mentioned above, is resistant to chemical and biological factors. The material will retain its properties, even if its structure is affected by:
- soap solutions;
- acids;
- salt solutions according to the type of sea water;
- bleaching agents;
- ammonia;
- gypsum;
- water soluble paints;
- adhesive solutions;
- lime;
- cement.
As for acids, polystyrene should not be affected by nitric or concentrated acetic acid. During installation, access to the material should be excluded from rodents and termites, because they can cause damage to the structure. Under the influence of concrete solutions, the material can partially decompose, as well 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 thermal conductivity coefficient of polystyrene foam was mentioned above, but it is important to know about the fire hazard of a material that is combustible, but has good fire resistance, because the auto-ignition temperature is 4910 ° . If we compare this indicator with wood, then it is 1.8 times higher, because for a tree only 2600 ° C will be enough.
Combustibility class and heat release ability
If the fire is out for 4 seconds, the material will die out on its own. During combustion, the insulation will produce heat in the amount of 1000 MJ / m 3 , as for wood, this indicator varies from 7000 to 8000 MJ / m 3 , which indicates that the temperature will be much lower during the burning of expanded polystyrene. On sale today you can find self-extinguishing polystyrene foam, which is made with the addition of flame retardants. But over time, this effect is lost, and the material that belonged to the G2 combustibility group will eventually belong to the G4 class.
Styrofoam Thickness
Expanded polystyrene, thermal 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. However, 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. Everything here will depend on the region of the country. For example, in the center of Moscow, the wall resistance should be equal to 4.15 m 2 ° C / W, as for the southern regions, 2.8 m 2 ° C / W will be sufficient here.