The properties and characteristics of the polyurethane its advantages and disadvantages

By Admin | Construction Materials
25 April 2016

About polyurethane foam, otherwise foam heard today is not only professional builders.Perhaps anyone who thought about own home insulation, this material is considered as one of the good options.After all, he is not only effective, but also very convenient for installation - it simply sprayed into place.A long service life and excellent quality foam has made it a kind of benchmark for insulation.We will understand what is so remarkable polyurethane foam, the characteristics of its look at list of dignity, as well as find out whether he had drawbacks.

The characteristics and properties of the polyurethane foam

Contents:

  1. What is polyurethane foam and how it happens
  2. On the technical characteristics PPU
  3. Table properties of polyurethane
  4. On the pros PPU
  5. About minuses PUF
  6. Video: insulated with polyurethane foam and its characteristics

What is polyurethane foam and how it happens

This material is one of the varieties of plastic.It has a cellular fo

am structure, wherein a polyurethane composition predominates gaseous - from 85 to 90 percent.Numerous tiny gas filled cells, isolated from each other.The remaining few per cent fall on the hard part - the thin walls of these cells.

polyurethane foam invented by German scientists from the company IG Farben, which led the famous Otto Bayer.However, at that time the name has not rattled.So, in a laboratory in Leverkusen after a series of experiments was obtained by the new material, the properties of which were unique.It became clear that this substance is lots of possibilities for use.

Different types of foam are in great demand today - in fact they are very easy to make, and once on the construction site.Thus two component liquid, mixing, chemically react.Subject to the relevant proportions of the polymer is synthesized, which is a solidified foam.Modifying the recipe, it is possible to obtain polyurethane foams, the properties of which differ from each other.Some of them are suitable for thermal insulation of windows and doors, while others - for insulation of houses made of brick or concrete, while others - for a variety of different pipelines.

Video: The process for obtaining a polyurethane foam

Thus, depending on the proportion of the starting materials, we obtain at the output of polyurethane with cells of various sizes, which walls have different thickness and thus strength.To list all kinds of polyurethane foam, which can be obtained changing the recipe, will not.Let us consider the two most popular materials of this group.

1. all familiar with foam rubber, scientifically called flexible polyurethane foam has a density of from 5 to 35 kilograms per cubic meter.This material meets us every day in the form of pads and sponges, filling the chairs and sofas lining in shoes and clothing, as well as shock-proof packaging.

2. Rigid polyurethane foam is not so long ago began to be used in construction work.But today, scientists can already say that it will be in 30 years or 50 - the material studied and tested.In addition, some laboratory experiments were conducted in which the foam was subjected to the procedure of artificial aging.Those and other results were the same.It's safe to say that the polyurethane foam insulation does not like contact with mineral acids and organic solvents.But water and oil, he is not afraid.

In our country we used quite a number of brands of hard foam - about 30. Apply them both individually and in various combinations with one another.It all depends on the application - it can be a warming of the house, protect it from the noise, creating an insulating layer on the refrigeration equipment.Such wide range of applications, this material was due to its wonderful properties.

The process of applying foam
spraying foam on the surface to warm.

On the technical characteristics PPU

we speak of rigid polyurethane - that they are used during construction.They canceled keep warm, almost passed steam and water are not afraid of corrosion, radiation and aggressive chemical environment.In addition, they are very durable, can withstand large temperature changes and extreme weather events.

thermal conductivity of polyurethane foam

properties as a thermal insulator depends on the size of its constituent cells.The thermal conductivity of rigid polyurethane foams ranges from 0.019 to 0.035 watts per meter per Kelvin.To be clear, this is an excellent result, we give examples of comparisons.In clay gravel, this parameter is from 0.12 to 0.14 watts per meter per Kelvin, while gazostekla and foamed glass - as much as 0.84 watts per meter per Kelvin.Yield polyurethane foam and mineral wool with a thermal conductivity of 0,045- 0,056 watts per meter per Kelvin.

Noise-capacity foam

noise absorption material is determined by several parameters: the elasticity, breathability and insulation thickness and its damping properties.For example, polyurethane foam capable of retaining the sound depends on how rigid frame material, and what is the frequency of sound vibrations.Important and friction that occurs when the transfer of particles between adjacent cells, as well as the absorption of sound waves from the air cells.By experiments it was found that the best protection from the noise floor of the flexible polyurethane foam type.

otnasheniya to chemical media

to aggressive chemicals polyurethane foam is more stable than polystyrene.PUF can not destroy the corrosive chemical vapors (concentration does not exceed the permissible).Not afraid of the insulation and gasoline, oils, alcohols, dilute acids and plasticizers.Proof enough, he refers to esters with ketokami.Even concentrated acid is not always able to damage it.

If you apply a layer of foam on a metal surface, it is not porzhaveet.After work with triple protection - as the polyurethane itself, and the two films, the outside and inside, resulting in polymerization of the material.One of the films will adhere to the metal, and the second - in contact with the external environment.Depending on the type polyurethane protective layer may be more or less effective.

Moisture absorption foam

Moisture absorption of this material is one of the lowest - per day, it can be up to 1 to 3 per cent of the original volume.This figure depends on the recipe prepare foam.The denser the insulation, the less water it is able to absorb.A more specific agents enhance the water introduced into the polyurethane foam.One such repellents, reduces the absorption of moisture by 4 times a normal castor oil.

Flammability

foam polyurethane foams may refer to three groups: C (self-extinguishing), TC (nonflammable) and TV (hard flammable).As you can see, the flammability of polyurethane foam is quite low.A fire helps boost his or introduction of special additives or changing the chemical formula of the recipe.The second option pricey, so often used method of introducing fillers.It can be a phosphorus compound, and halogens.It is possible to apply a conventional polyurethane foam flame retardant polyurethane thin layer containing additives.In production areas where fire risk is high, a coating applied two layers would be appropriate.

Video: Lights if polyurethane foam - a test for flammability

density foam

density of the insulation varies from 30 to 80 kilograms per cubic meter.This rate depends on whether the technology used in the production of the material.Basically, it's a good idea - at warming may require more stringent, and softer materials.Everything depends on the specific task.So sometimes you can get substantial savings by applying a cheaper less density foam.

durability polyurethane

Lifetime foam manufacturers claimed no less than 20-30 years.But there is evidence that the real figures are much higher.In the US, German, Swedish and Japanese cities today is the dismantling of buildings built in the seventies of the last century.If their construction was used for thermal insulation of polyurethane foam.After examining his specimens from pipes, walls and roofs, experts have concluded that the material remained unchanged in all respects.Isolated remains of nine-tenths of all the cells, allowing still good save heat.Chemical status is also not changed.And laboratory and industrial tests in unison confirm this.

Environmental safety and the impact on human

After 10 - 20 seconds, during which the material hardens, polyurethane foam is absolutely secure.If it is heated to a temperature over 500 degrees, it will start the selection of two gases: carbon dioxide and carbon monoxide.But if put in place foam or rubber tree, then at the same temperature, they will be more dangerous.Experiments on mice have confirmed this.

Table properties of polyurethane

Options minimum and maximum values ​​
Thermal conductivity, W / m Kelvin 0,019 - 0,035
Density, kg / m from 26 to 300
voltage at which the material begins to break down, MPa compressive 0.15 to 1,0
flexural 0,35 to 1,9
Water absorption,% by volume from 1.0 to5,0
Group material flammability GOST 12.1.044 (retardant)

On the pros PPU

Reasoning is not about abstract technical characteristics of polyurethane foam, and its specific application, the following advantages ofinsulation:

1. foam excellent "sticks" to any material, whether brick, glass, wood, concrete or metal.The form of the surface, its deviation from straightness of no importance.Thanks to the good adherent properties, there is no need to split hairs with the installation of an additional fixture.Incidentally, before spraying the plane does not need to handle.

Adhesion of foam
polyurethane has excellent adhesion with respect to almost all building materials.

2. This insulation is made on the spot, and the amount of the initial components is minimal.Therefore, transport costs are low.

3. Polyurethane different unusual move, he does not weigh down the surface.When the roof insulation is very important.

4. When applying the foam layer we have not only insulated walls and partitions, but also makes them more durable.

5. polyurethane coating does not react to the warming and cooling throughout the year.It thrives at temperatures from minus 200 to plus 200 degrees Celsius.

6. In contrast to the panel and sheet insulation, this type of insulation is a single whole, tight-fitting design.Nowhere joint or a small seam, which can blow out the cold wind.

RTD does not require fasteners
Install foam can be anywhere and without the use of fasteners.About

cons PPU

This article is not advertising, so listed and negative properties of polyurethane foam.However, they are quite a bit, or rather two.

1. negative effects of UV radiation can lead to a rapid deterioration of the material.In order to prevent degradation of insulation, it is necessary to provide for his defense.This can serve as a plaster, various panels or ordinary paint, which not only will protect from the sun, but also make the surface of the foam more attractive.

2. As mentioned, foams are considered to be slow-burning materials.By classification, they have a group of combustibility G-2.This means that when exposed to heat of fire does not happen, but the heater starts to smolder.This process will stop immediately, as soon as the material is cooled.But where the surface is too hot or it may catch fire, use the foam is still not worth it.

Video: insulated with polyurethane foam and its characteristics

Additions
  • reviews the application of polyurethane foam insulation

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