The 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 is 98% air. It is encased in expanded polystyrene cages.
The structure is completely safe for he alth, so the material is used to make food packaging. It is easy to process, widely used in the construction industry, and also has a low cost.
What you need to know about the thermal conductivity of Styrofoam
The thermal conductivity of expanded polystyrene is quite low, because the air that is at the base 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 0.027 W / mK.
Expanded polystyrene is manufactured according to GOST15588-86 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 expanded polystyrene can be used 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 interior, but also for exterior decoration. However, this characteristic will vary depending on the density. The higher it is, the greater 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 0.028W / mK, because styrene granules in this case are in the structure of a solid sheet, and there are no gaps between them.
Comparison of thermal conductivity of different brands
For comparison, we can consider several grades of expanded polystyrene, the density and thermal conductivity of which differ. The density of PSB-S15 does not even reach 15 kg/m3, while the thermal conductivity ranges from 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/m3, while the thermal conductivity is 0.038 W/mK. On sale you can also find extruded polystyrene foam. In grade 35, the density varies from 33 to 38, while the thermal conductivity is 0.03.
If you have stamp 45 in front of you,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 inherent in other materials. For example, expanded clay concrete with a density of 1200 kg/m3has a thermal conductivity of 0.58.
Comparison of the thermal conductivity of Styrofoam 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 quite 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 for reinforced concrete it will be 2.04.
Expanded concrete and foam concrete have thermal conductivity equal to 0.58 and 0.37, respectively. Expanded polystyrene, for comparison, has a thermal conductivity of 0.028W/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 when it comes to slabs.
Main features: safety, soundproofing and windproof performance
Styrofoam is safe and reusable. At the same time, harmful substances will not be released into the environment. According to studies, hazardous styrene has not been found in building structures made of expanded polystyrene. With regard to soundproofing andwind protection, then when using expanded polystyrene, there is no need to additionally use materials that increase windproof functions and sound insulation.
If the sound absorbing capacity needs to be increased, 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 be aware of before purchasing this material. For example, expanded polystyrene is not hygroscopic, therefore it does not absorb water and moisture, does not swell or deform, and also does not dissolve in liquid. If expanded polystyrene is placed in water, only 3% of the board's weight will penetrate into the structure, while the material properties will remain unchanged.
Steam and water escape quite easily from Styrofoam, so care must be taken to avoid condensation. For this, design rules are followed. The moisture resistance of expanded polystyrene allows it to be used for insulation of the foundation, where contact with the ground is inevitable.
Additional features: biological and chemical inertness
Insulation foam polystyrene, 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:
- soap solutions;
- acids;
- saline solutions by type of sea water;
- whitening products;
- ammonia;
- gypsum;
- water-soluble paints;
- adhesive solutions;
- lime;
- cement.
As for acids, Styrofoam should not be affected by nitric and concentrated acetic acids. During the installation process, 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 may partially decompose, as well as under the influence of organic solvents. Stability can be determined by the ratio of open and closed cells, which depends on the brand and type of insulation.
Fire resistance of Styrofoam
The thermal conductivity of expanded polystyrene was 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 we compare this indicator with wood, then it is 1.8 times higher, because only 2600 ° C will be enough for a tree.
Flammability class and ability to generate heat
If there is no fire for 4 seconds, the material will die out on its own. During combustion, the insulation will release heat in the amount of 1000 MJ/m3, as for wood, this figure varies from 7000 to 8000 MJ/m3, this indicates that when the Styrofoam burns, the temperature will be much lower. On sale today you can find self-extinguishing polystyrene foam, which is produced 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 must know 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 better 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 resistance of the wall should be 4.15 m2°C/W, as for the southern regions, 2.8 m will be enough here2 °C/Tue
