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Description of Polyfoam
Comparative Table of Thermal Materials

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Polyfoam (cellular polystyrene) for thermal protection is non-extrudedly made of frothing suspension polystyrene. Polyfoam (polystyrene) is frothed with the help of natural substance (pentane). Pentane is quickly decomposed in atmosphere, soil or water. In processing granules of polystyrene are influenced by water steam. As a result, equally frothed mass with a fine closed-cellular structure is formed. 1m3 of such a material is 98% full of air convicted in 3-6 milliards of closed cells. Thanks to its inner structure it has got low heat conductivity, close to conductivity of non-moving air (conductivity factor is about 0,00006 cal/cm. sec. grad, i. e. 0,00006 calories go thought each cubic centimeter with 1 degree difference of temperatures and 1 cm thick every second). So polystyrene is stark hard polystyrene mass with closed cells full of air which is ecologically safe constructive material. Quality of polyfoam (polystyrene) extensively depends on equipment technology and raw material either with fire-retardant or without it.

Heat engineering features

Polyfoam (polystyrene) has low heat conductivity what is conditioned by air, taken in hard interstices. When density of polystyrene increases, emanation decreases and conductivity through polymeric matrix increases.

Diffusion of water steam and water absorbing

Cellular polystyrene doesn't dissolve, swell and absorb water. Water can penetrate into a maze between frothed granules but it doesn't effect mechanic stability, size, physical form or insulating features. Besides, thanks to high degree of frothing between granules taking of water is minimal.

Water in its gas phase can penetrate into cellular polystyrene though the speed of moving is less than 1% in comparison with the speed of water moving. Steam will leave polyfoam with the same speed. Actually, such situations are easy to prevent with the help of necessary specifications, control and corresponding constructive designing.

By designing impermeability for water steam must decrease in the line of necessary flow. So outdoor walls impermeability must decrease inside out for inner surface was dry. That's why water noise in insulating course has negative effect. It's important as water in insulating layer decreases thermal protection effectiveness. This influence is not great: 1% of water takes 4% of thermal protection effectiveness. However, by competent designer's and constructer's work this effect is reversible and allows not to keep moisture in a construction.

Stability to chemical influences

Nowadays the problem of wallsaltpetre and mould in constructions is widely discussed. Polystyrene in front systems is the way out as polystyrene plates are stable to the influence of mineral medium such as lime, cement, gypsum, clay, bitumen, stable to some other chemical substances (table).

Stability of polystyrene to chemical substances effect.

Influencing substances

 

Salt solution (sea-water)

+

Soap and wetting agents

+

Blanching agents: hypochlorite, chloral water, hydrogen peroxide

+

Dissolved acids

+

Hydrochloric acid 35%, nitric acid 50%

+

Arid oxygen, nordhausen acid, formic acid 100%

-

Sodium hydroxide, liquid ammonia

+

Organic solvers: acetone, acetic ester, benzol, xylene, lacquer solvent, trichloroethylene

-

Aliphatic hydrocarbon, medical benzene, white spirit

-

Paraffin oil, Vaseline

+-

Diesel oil

-

Carburetor fuel

-

Spirits: methanol, ethanol

+-

Organosilicic oil

+

+      stable: cellular polystyrene doesn't destroy even under long lasting effect

+ -  conditionally stable: under long lasting effect polystyrene can contract or destroy its surface layer

-     non-stable: cellular polystyrene contracts or dissolves

These properties are the main but not the only ones.

Inflammability of cellular polystyrene

One of the main questions is cellular polystyrene inflammability.

Thermal value of cellular polystyrene is 40 MJ/kg, i.e.
15 kg/m3 – about 600 MJ/kg
20 kg/m3 – about 800 MJ/kg
25 kg/m3 - about 1000 MJ/kg
For comparison, thermal value of wood is about 7000-8000 MJ/kg.

Cellular polystyrene ignition goes in open fire with soot allocation and burning digressive drops forming. However, the material with modified fire-retardant additive is different.

Therefore, inside a construction, first polyfoam melts, then it goes into gaseous state. Energy part of polyfoam in the burning process is less than 2 % of all inflammable agents, i. e. less than any other material. So, it can be widely used in construction. Water in polyfoam fire extinguishing is not poisonous.

Temperatures of operation

Cellular polystyrene keeps its properties in a wide range of temperatures from +80oC to -180oC. During brief periods of time polystyrene stands temperatures to 110oC and allows brief contact with inflammable bitumen. Nevertheless maximum allowed temperature is 95oC. In constant putting to high temperatures don't exceed 80oC, otherwise it leads to contraction and deformation. Low temperature level is 180oC. Take into account that temperature expansion is insignificant, so in practice polystyrene stands all standard construction temperatures.

Longevity of cellular polystyrene

Cellular polystyrene plates (essentially plastic) are steady to ageing and keep stable properties for a long time, i.e. it is long-lived material. Field data and expert opinion prove that 30 years-old material doesn't undergo irreversible change. It is significant that cellular polystyrene producing technology is 50 years old only. However, Moscow research institute tested polystyrene to longevity and year cycle temperature changes in the middle-Russia climate. Eighty-cycle tests show that cellular polystyrene plates stand the test perfectly well. They can stand the same quantity of years exploitation with different temperature effect.

Dynamic inflexibility

Dynamic inflexibility is connected with thickness of ready-make. It is a very important factor of soundproofing. Because of its closed-cellular structure polystyrene is not quality soundproofing material for sound diffusing in the air.

Ease and comfort of assembling

Thermal protecting cellular polystyrene plates are mechanically operated easily. With the help of easy tools it can be cut to peaces of any size and form.

Stability to biological exposure

Cellular polystyrene is not assimilated by animals and is not used as food. In the same way, material is not nutrient medium for fungi and bacteria. Of course, its structure is not stable to rodents and insects, so if accident is possible access to polystyrene must be prevented.

…Polyfoam keeps warmth perfectly well. Polyfoam in outdoor walls of apartment houses allows to decrease heat loss. According to research-and-development test, polystyrene of 12 cm thick is equal to:

-0,5 m timber wall thick,
-2 m brick wall thick,
-4 m reinforced concrete wall thick.