Expanded polystyrene (foam) is white insulation material that is made of air 98%. Products made of expanded polystyrene (Styrofoam) are biologically safe and are used for food packaging. Expanded polystyrene is resistant to moisture, is not exposed to microorganisms. Being the most effective, for more than 30 years insulation foam (Styrofoam) is used for thermal insulation of roofs, walls, ceilings and floors in residential and commercial buildings. Ease of handling with a hand saw or a knife, light weight, the ability to bond with a variety of building materials, simple mechanical attachment all those are undoubtedly advantages of expanded polystyrene (Styrofoam).
Styrofoam Technical Characteristics
Heat-saving properties of the insulation boards are based on the fact that the air has one of the lowest thermal conductivity (0.027 W / mK), so the thermal conductivity of the insulation boards is in the range of 0.037 to 0.043 W / mK. This is significantly lower than the thermal conductivity of wood (0.12 W / mK), brick (0.7 W / mK), expanded clay (0.12 W / mK), and other building materials.
The low thermal conductivity of the insulation boards provide a high level of energy saving. It takes only 12 cm foam where the necessary thickness of the brick wall should be 2 m 10 cm and 45 cm of wood. This suggests styrofoam as one of the most efficient heat insulators.
The usage of foam plates in the construction allows for future to significantly reduce heating costs. High energy-saving properties of polystyrene plates led to their use and to protect pipes from freezing, thereby increasing their lifetime.
Moreover, heat-saving properties of the foam are useful for refrigeration and storage spaces.
Due to its structure polystyrene is not hygroscopic and does not absorb water, does not dissolve or deform (or swell). Nevertheless, through capillary diffusion mechanism water can penetrate into the cavity between the foam beads. However, its amount is very low (1.5 - 3% relative to the weight amount of expanded polystyrene plates). Moreover, the same mechanism of diffusion and release conducts water from the foam. The properties of polystyrene plates (strength, size, insulating ability) remain unchanged. The rate of penetration of water vapor in polystyrene plates is less than 1%.
Just as water, steam easily goes out from foam. Proper projection gives an opportunity to avoiv condensation. Resistance to moisture allows the usage of polystyrene plates for thermal insulation of building foundation.
Resistance to chemical and biological effects
Polystyrene plates are highly resistant to various chemicals. In particular polystyrene retains its properties during prolonged contact with brine (including seawater), soaps, bleaching products (hydrogen peroxide solutions, bleach water, hypochlorite), acids (except concentrated nitric acid and acetic acid), ammonia, lime, bitumen, adhesive water-soluble paint, plaster, cement, etc.
Expanded polystyrene is not affected by micro-organisms, does not create a good environment for the development of algae and fungi and is not used in food animals.
Density of polystyrene plates is low - 0.015-0.05 g/cm3 (compared to water density 1.0 g/cm3). However, the polystyrene has a sufficiently high compressive and flexural strength. For instance, it can be used for construction of runways, roads and etc. In this case, the strength of polystyrene plates depends on the thickness of the plate and proper installation.
The effect sound of insulation and soundproofing material depends on the ability to convert acoustic energy into heat. Therefore, the ability to exhibit high sound absorption, especially porous materials with low thermal conductivity that are capable of transmitting air.
For example, to provide insulation, the thickness of foam showld be no less than 2-3. Alongside with increasing the thickness of foam plates insulating properties are increased.
With proper usage of polystyrene plates are able to maintain their physical properties for a long time.
Invastigation of polystyrene plates showed that the foam is not exposed to irreversible changes: it retains its shape mechanical and thermal properties for a long time. It was also stated that the lower limit for the foam is –1800С, and the highest +800С. However, the maximum temperature, that polystyrenecan be expanded is +95°C. This makes it possible the contact of polystyrene plates with hot bitumen. With more prolonged exposure to temperatures above +800С, polystyrene foam collapses.
Under the influence of moisture and oxygen (air), natural organic materials may deteriorate (rubber, wood, leather, textile materials). Expanded polystyrene does not decay.
Expanded polystyrene has a high fire resistance. Auto-ignition temperature of styrofoam is +4910С. This is 2.1 times higher than the ignition temperature of the paper (+2300С), and 1.8 times higher than that of wood (+2600С). Despite the fact that the polystyrene plates, as well as many other construction materials are exposed to combustion, nevertheless, they do not support combustion, and in the absence of fire fade within 4 seconds. In other words, the combustion of polystyrene plates is only possible with an open flame, and after removing the foam from the fire burning stops.