Specially designed corrugated outer surface makes tubing are resistant to stress. Thanks to flexible tubing structure any seismic movement of the soil did not influence them.

Characteristics of polyethylene provide resistance to being in the wastewater chemicals.

Temperature-resistant up 80oS

The smooth inner surface and low coefficient of friction provide high speed transmission drains. The degree of smoothness of the inner surface of tubing Firat (FIRAT) is close to the index of smoothness of the surface of the glass, so the tubes do not form deposits.

Corrugated tubing can be used not less than 50 years and work with, like the first day of pads.

Owing to the peculiarities of the molecular structure of polyethylene corrugated tube elastically deformed under the influence of loads, absorb external loads, and again take its original shape. Boundary constant strain can grow to 7.5%. While the other tubing in such a strain burst, corrugated continue their work.

Pluses – low weight at a sufficiently high strength, high corrosion resistance, smooth surface and, accordingly, high capacity, low thermal conductivity, the absence of fouling of the walls, easy installation of networks, aesthetic quality.

Cons – dependence of the strength of the pipe from the pressure and in particular on the temperature of the transported fluid, a low maximum operating temperature (not above 100 ° C), high coefficient of thermal expansion (approximately 10 times higher than that of steel), a rapidly aging under direct sunlight , the high diffusion coefficient of oxygen through the pipe wall.

In assessing the advantages and disadvantages of various plastic pipes should be considered:

* For the production of pipes used by a number of polymers with different properties;
* Modern production technology of polymer pipes using different methods, leveling deficiencies of polymers;
* Optimum results from the use of plastic pipes can be obtained by properly selecting the type of pipe for a given operating conditions.

The seriousness of the role of polymeric pipes in the overall balance of pipes in Europe and the USA we have shown in the previous issue of the journal Stroyprofil. In U.S polymer pipes while the absolute amount of cover is not the lead, but the prospects of their application is already reflected in the regulations. Thus, in SNIP 2.04.01-85 “Domestic water supply and sewerage Buildings amended ї 2 in Section 10.1, is recommended for internal networks of hot and cold water pipes and polymer fittings are made of polyethylene, polypropylene, polyvinyl chloride, polybutylene, and metal-polymer composites tube.

• chemical composition of products;
• the angle at which establishes the samples were exposed to the environment;
• time of the year in which testing is conducted;
• geographical location of the test.

The efficiency of microorganisms strongly depends on the chemical composition of the material. Polymers, which are well resist the action of moisture and are stable in different weather conditions tend to have high resistance against the microorganism, because on the surface of products made of such materials are not allocated plasticizing components, and does not create a breeding ground for microorganisms. Products that have the ability to partially flush with the surface of microorganisms, have certain advantages because microbes have a major impact is on the surface.

The angle at which the samples during the exposure target in relation to sunlight and atmospheric effects, in general, affects the efficiency and duration of microbial exposure. For some PEX plastics is characterized by a rapid release of additives play the role of the medium, if they are installed at an angle of 40 degrees to the south, than if they are placed vertically.

Time of year and geographical location tests also play an important role, because bacteria grow more active in warm and moist atmosphere than in the cold and dry climate.

In conclusion, we note that the test for resistance to bacteria and fungus must be conducted in two stages. First, you should perform short-term accelerated tests that will screen out materials that do not pose long-term interest. Secondly, the long-run full-scale tests, which are intended to confirm the results of laboratory evaluations.

Of course, one of the key issues is the question of quality products. The high interest is a modified polyurethane foam fillers or additives. One of the most successful, popular and sealed modifiers polyurethane systems around the world are the polymer-polyol additive. They have become an integral part for the polyurethane foam.

In this article we want to know more about you, the polymer-polyol, their species, chemistry of receipt and functionality. So let’s begin.

Polymer-polyol – a viscous homogeneous suspension of white. When adding a polymer polyol in component A in the amount of 10-20% (by weight) increased carrying capacity in multiple strains and elasticity of the foam. In addition, increased longevity of the products of polyurethane foam, as well as decreasing the number of surface defects. Adding a polymer polyol in various proportions can control the physical and mechanical properties of polyurethane foams.

Achieving a set of properties is partly due to the fact that the polymer-modified polyol polyesters by chemical interaction with poliizotsionates form chemical skeleton (a grid of chemical bonds) with a rigid polymer fragments.

The main types of polymer polyols:

There are three classes of industrial modified polyols:

A) Polymer-polyols – dispersion poliakrilnitril, polystyrene (SAN).
B) with a dispersion of polyurethane polyols (PHD).
B) poly-isocyanate with polyols polidadditons (PIPA) – the dispersion of polyurethane.
D) Other-polymer polyols.

Now let a little more detail on each type of polymer polyols.

A) Polymer-polyols – dispersion polyacryl-nitrile, polystyrene (SAN).

This type of polymer polyol obtained by chain polymerization of styrene, acrylonitrile and polyester. Consider the basic chemical reactions that occur during free radical polymerization:

Description of the reactions:

1) First, free radicals are the result of rupture of the molecule of initiator, typically aliphatic azobis-nitrile compounds.
2) The radicals quickly react with monomer molecules with the formation of high molecular polymer. This stage is known as polymerization chain growth. This reaction differs significantly from the slow speed of polymerization of isocyanates and polyols.
3) The chain growth terminates the interaction of two different radical chain ends.
4) chain transfer agents react with the growing ends of the chains and terminate their growth. New radical terminal groups can initiate further chain growth polymers. Agents break the chain will stop the growth of the chain and not allow re-initiate the polymerization. These types of agents, eventually, slow down and stop the polymerization.

We can say that these types of chemical reactions is the basis for polymer-polyol. Depending on the type of polyester used in the synthesis of this type of polymer polyol has a viscosity in the range from 3000 to 7000 (to 9000) MPa • s. The resulting dispersion is used in the production of highly elastic foams by cold molding to improve the elasticity and strength products, as well as increasing their lifetime.

The first industrial polymer polyols were obtained using acrylonitrile as the sole monomer.

Background of acrylonitril:

1) Acrylic acts like hydrogen cyanide, causing tissue hypoxia, irritates skin and mucous membranes;
2) Refers to substances probably carcinogenic to humans (GN 1.1.725-98 “List of substances, products, production processes, household and environmental factors, carcinogenic to humans”);
3) A serious danger is the possibility of fire and explosion, low temperature ignition of acrylonitril indicates that the evaporation at room temperature is sufficient to form a combustible mixture with air;
4) Acrylonitril is capable of spontaneous polymerization under the influence of light and heat, which can lead to an explosion, even when it is stored in sealed containers;
5) The risk of fire and explosion increases deadly products of combustion such as ammonia and hydrogen cyanide.

Until now, virtually all imports of polymer polyols contain in the structure described above monomer. The question arises, why would you use in the production of polymer polyol is a substance? And because it is involved in the synthesis of the second monomer – styrene, which after synthesis is in the reaction mixture and it is very difficult to bring to the end. Acrylonitril in the amount of 10% helps to remove the residual styrene and get rid of the smell.

Our company took a different path, developing a new technology for polymer polyol, which is not used acrylonitril, and in the final product is no residual styrene.

B) with a dispersion of polyurea polyols (PDM).

Produced by stepwise polymerization. The first of these products was a polyol based on PDM (polyurea dispersion). DPM-polyols are dispersions of particles in the standard polyurea polyols. Such polyols are prepared in the reaction of diamine with diisocyanate in the presence of polyester with terminal hydroxyl groups. Mechanisms of instilling and polymerization are significantly different from those used for the polymer-polyol styrene and acrylonitril. The reaction of the base polyol to diisocyanate is slower than the reaction of diamine with diisocyanat, and their tendency to form small “seed” particles much smaller than that of polyols, styrene and acrylonitril. This leads to a weak implementation grafted polyols and to a deterioration in control of the formation of nuclei (active centers). The result is the larger particles and a wider distribution on polymer polyols, styrene and acrylonitril.

The viscosity of PDM-polyols higher than that of copolymer polyols, styrene and acrylonitrile. The first generation of PDM-polyols containing 20% of solid particles with a viscosity of 3000 to 3500 santiplaz. Newer products contain 28% solids.

B) Polizotsianatnye polyols with polidobavkami (PPPITS-polyol) – the dispersion of polyurethane.

PPPITS-polyols are similar to the PDM-polyol, but, unlike them, contain dispersed particles of polyurethane, formed in the reaction of isocyanate and alkanolamines such as triethanolamine. In general, amines are added to the standard polyols and the mixture quickly into contact, for example, toluene diisocyanate with rapid stirring. If you accelerate the reaction of organotin catalyst, it may be over in five minutes.

PPPITS-polyols are usually made and used by producers of foam.

D) Other-copolymer polyols

Polyols based on epoxy dispersions

There is information about the filled polyols based on the variances of cured epoxy resins. Stabilization of the particles occurs by using a specific polyol, which reacts with epoxy resin. It is reported that epoxy particles are more high-modulus fillers with improved ability to form hydrogen bonds.

Polyols based on the variance poliizotsianurata

This dispersion of particles in the standard poliizotsianuratov polyols. The particles prepared in the solvent, is dispersed in the polyols and the resulting solvent gives the finished product. Stabilization of the particles is achieved by the reaction of particles with monofunctional poliizotsianurata halogenated alcohol.

Polyols based on the dispersion of melamine

There is evidence to reduce the flammability of using copolymer-polyol-based melamine. However, the influence of particle size melamine on the physical properties of the finished foam has not been studied.

In Russia the most popular found the first type of polymer polyol (dispersion polyacryl-nitrile, polystyrene (SAN)) and is used mainly producing foam rubber and automobile seats. It is worth noting that many manufacturers still do not use the polymer-polyol additive, producing low quality products. The reluctance to apply the additive in their production due to several factors:

1) An import expensive additive that increases the value of the final product
2) Lack of awareness about the additive and its benefits
3) Do not want to make unnecessary movements and change the production process

Try to refute the above arguments:

1) address the issue with the appreciation of the final product will be the use of polymer-polyol supplements domestic production.
The scientific team developed and patented a new technology for polymer-polyol (trademark Laps 48-40). The market value of supplements is almost equal to the value Laprols 3603.

2) Summary of the benefits of supplements. Polymer polyol increases the carrying capacity in multiple strains, elasticity and durability of foam products. In addition, the reduced number of surface defects and, in total, increasing product quality. When added to component A in various proportions can control the physical and mechanical properties of polyurethane foam, for example, increase the hardness and elasticity at constant water content in the recipe and equal density foam.

3) Contrary to fears of producers to change anything in the manufacturing process, we simply give way to introduce additives: Polymer-polyol is added to the amount of 10-20% in the total mass is used instead of polyester, while the composition of other ingredients in the recipe does not change.

Author: Eganov Ruslan, Artyom Sevastyanov
Source: “Himtrast” CJSC