Technical characteristics of polypropylene pipes.

The main parameters in the construction of pipelines have always been reliability, durability and low price. Polypropylene products used in the construction of various kinds of communications fully comply with each of these requirements. Their peculiarity is not only in unique technical characteristics and high performance. Simplicity and manufacturability of installation of polypropylene systems contribute to their popularity not only in professional construction, but also among ordinary users.

Polypropylene pipes

The invention of the Random Copolymer (PP-R) thermoplastic was a breakthrough in the field of plastics. High temperature resistance and excellent technical characteristics allow the use of products made of this type of plastic in many industries. How unique this material is can be imagined even from an incomplete list of the main advantages of products made from this copolymer:

• high strength;
• low adhesion;
• chemical inertness (polypropylene is absolutely non-toxic);
• low coefficient of thermal conductivity;
• good sound insulation;
• the ability to withstand temperature and pressure fluctuations over a wide range;
• durability;
• economy of transportation and installation.

Despite the common origin, polypropylene products differ significantly in their properties and performance.

Products of European quality, from an exclusive supplier in Russia! You can buy Aquatherm pipes, as well as piping and fastening systems, on this website https://agpipe.ru

When choosing pipes from this material, be sure to check that their technical characteristics correspond to future operating conditions.

In addition, depending on the application, the pipes can be reinforced with aluminum foil or fiberglass. Depending on this, they can be used:

• for water supply (both cold and hot);
• in the agro-industrial complex;
• in underfloor heating systems;
• for heating systems;
• in systems of transportation of chemical compounds;
• in pipelines of compressor installations.

It would be dishonest to keep silent about the main disadvantage of polypropylene pipes - their coefficient of linear expansion is 0.15 mm / m ° C (about 10 times more than that of steel), but this problem is successfully solved by the production of reinforced products. The use of an aluminum armored belt can reduce the thermal expansion of polypropylene by more than five times.

Random polypropylene copolymer in granules

Basic physical and mechanical parameters

The Russian standard for "Pressure pipes made of thermoplastics and fittings for them for heating and water supply systems" (GOST 521343:2003) establishes six classes of operation of polypropylene pipes depending on the nominal temperature:

1. Application in hot water supply (up to 60°С).
2. Application in hot water supply (up to 70°С).
3. Use in floor heating systems (low temperature - up to 60 ° C).
4. Work in systems of high-temperature floor and low-temperature radiator heating (up to 70°С).
5. Work in systems of high-temperature radiator heating (to 90 °C).
6. Application in cold water supply (class designation - ХВ).

Table of PPR pipe service life as a function of pressure and temperature

Characteristics

• The density of polypropylene is the lowest of all plastics - 0.91kg/cm2. Despite this, the surface of products made from it has high hardness and wear resistance.
• The mechanical strength of PP-R pipes depends on the time the force is applied, and since this parameter is associated with gradual heating or cooling, we can talk about strength sufficient for any operating conditions. By the way, the limit value for PPR is 35 N/mm.
• Increased resistance to chemically aggressive environments - surface destruction is possible only when high-temperature exposure is combined with a strong acid.
• Frost resistance - not less than -15 ° С. Most often, pipes work with a coolant of positive temperature, so even such outstanding indicators are quite enough.
• The melting point of polypropylene is from 160 to 170°C, depending on the composition.
• The softening point is 140°C.
• The maximum heat carrier temperature is not more than 120°С.
• Working pressure - from 10 to 25 atmospheres.
• External diameter - from 16 to 125mm.

The bending radius of the pipes depends both on their diameter and on the presence and type of the reinforcing layer. The maximum parameter is for polypropylene pipes with aluminum reinforcement without perforation.

Marking and dimensions

Pipe marking

The labeling of polypropylene products can include both material information and nominal pressure and temperature data. The letter index means:

• PP is plain polypropylene.
• PP-R is a polypropylene random copolymer.
• PP-RC is a type III polypropylene random copolymer designed for hot water supply and heating systems.
• PP-RCT is an improved polypropylene random copolymer.

PP-RC pipes are exactly those products that are used in water supply and heating systems. They are most often used in industry and agriculture.

Diagram of thermal expansion of pipes made of various materials

The letter designation of pipes is PN, while there are four product modifications, depending on the nominal working pressure for which they are designed:

• PN10 - liquid pressure up to 10 atmospheres. Pipes PN10 are used for transportation of low-temperature coolant (up to 45°C) in cold water supply systems or underfloor heating.
• PN16 - pressure in the system is allowed no more than 16 atmospheres, and the operating temperature should not exceed 60 ° C. Recommended for use in low temperature heating systems.
• PN20 is the most common brand. Allows transportation of liquids up to 95°C at pressures up to 20 atmospheres, due to which it is used both in heating systems and in pipelines for hot water supply.
• PN25 - has the lowest coefficient of linear deformation, withstands long-term fluid pressure up to 25 atmospheres at temperatures up to 95 ° C.

PN pipes can be reinforced with fiberglass or with aluminum foil. In the second variant, both perforated and monolithic tape can be used as a reinforcing layer. In heating systems, it is recommended to install pipes without foil perforation. Such products most successfully resist the diffusion of air into the coolant.

In everyday life, pipes with an outer diameter of 20, 25, 32, 40 mm are most often used. The main parameters of pipes of the most common brand PN20 are summarized in the table.

Table of technical characteristics of PN20 polypropylene pipes

Manufacturers and assortment

Many large companies around the world are engaged in the production of pipes from polypropylene. The process of their manufacture differs both in technology and in the use of material of various modifications. Here is what the rating of manufacturers of polypropylene pipes looks like:

1. Banninger Reiskirchen PPR pipes are rightfully considered the best products. Only the highest quality PP-RCT polypropylene (Wefatherm brand) is used for their production. No wonder German engineers have installed a 10-year manufacturing warranty on their products.
2. Polypropylene systems of the Czech manufacturer WAWIN Ecoplastik are pioneers in the industry. The quality of products is practically in no way inferior to pipes from Germany, as well as the exorbitant price, which limits their distribution in our country.
3. Known to all company Valtec from Italy. Products are optimal in terms of quality / price.
4. Turkish and Polish manufacturers (TEBO, Vesbo, Pilsa and others).
5. Products of Chinese and domestic companies.

Each of the manufacturers produces a wide range of pipe grades, fully covering all possible consumer needs. As evidence, we present the range of the Italian brand Valtec, which is comfortably located in the middle of our list:

1. Pipe Valtec PPR PN20. Installation in systems of water supply is allowed. Water temperature - no more than 70 ° C, pressure with a cold coolant - up to 20 atmospheres, with a hot one - no more than 10 atmospheres. It does not have a reinforcing layer. According to Russian GOST, it belongs to 1,2,XV classes.
2. Valtec PP-FIBER PN20. Application in water supply of any type and heating systems with heat carrier temperature up to 90 °C is possible. Working pressure is similar to the previous brand. The pipes have a three-layer construction with fiberglass reinforcement.
3. Valtec PP-FIBER PN25. Products of this brand are designed for high pressure - up to 25 atmospheres in "cold" pipelines. Pipe diameter starts from 20mm.
4. Valtec PP-ALUX. Due to the presence of aluminum reinforcement made of solid foil, the pipes are able to operate in systems with temperatures up to 95 ° C at pressures up to 10 atmospheres. In pipelines with cold water, this value is 25 atmospheres.

Of course, with the growth of technical indicators, the cost of products also increases, however, we repeat that the quality of Valtec products is comparable to world brands, and the price is much lower.

Going to the store, pay attention not only to the price, but also to the technical characteristics of the products. Select pipes with a small margin according to the main operating parameters.

1. Operating pressure. Manufacturers indicate its value for room temperature, therefore, when choosing pipes for the heating system of an apartment, pay attention to products of the PN25 brand. If you are the owner of a home with individual heating, pipes marked PN20 will suffice.
2. Temperature. For reinforced pipes, manufacturers indicate a coolant temperature of at least 90 ° C. You should not overpay for products with the inscription 95 ° C - their characteristics are the same.
3. Diameter. For risers with a diameter of ¾ inch, a pipe with a diameter of 25 mm is required, and for inch risers - 32 mm. For linear wiring, 20mm products are most often used.
4. For heating and hot water supply, choose only reinforced products.

When choosing pipes, remember that their manufacture is a high-tech process. Therefore, do not be tempted by the low price of Chinese products - the slightest violation of technology leads to delamination of pipes during operation. And this is fraught with big troubles.

Even products with the most impressive characteristics from a world-famous company will not be able to fully work if the installation of the system was initially carried out carelessly and with miscalculations. Pay this closest attention when building pipelines from polypropylene pipes with your own hands.

Thanks to my versatile hobbies, I write on various topics, but my favorite ones are engineering, technology and construction. Perhaps because I know a lot of nuances in these areas, not only theoretically, as a result of studying at a technical university and graduate school, but also from the practical side, since I try to do everything with my own hands.

It is a strong and tough, crystalline thermoplastic polymer derived from monomeric propylene. Polypropylene is a linear hydrocarbon polymer. Polypropylene has the chemical formula (C 3 H 6) n. Today, polypropylene is one of the cheapest of all plastics available.

Polypropylene is used in practice both in the form of plastics and in the form of fibers in the following areas:

– automotive industry;
– construction (pipes, etc.);
– production of consumer products;
- package;
- furniture manufacture.

Types of polypropylene

The two main types of polypropylene available on the market are homo polymeric (homopolymers) and SOPO polymeric (copolymers) material grades.

– Homopolymer polypropylene is the most widely used general purpose grade of this polymer. The homopolymer polypropylene molecule consists only of propylene units, and the material itself is in a partially crystallizing solid state. This material is mainly used in the production of packaging, textiles, medical products, pipes, automotive components and electrical components.

– Copolymer grades of polypropylene subdivided into random-copolymers (propylene random copolymer) and block-copolymers, which are obtained as a result of the copolymerization of propene and ethene.

A) Random copolymer Propylene is obtained by the copolymerization of ethene and propene. The molecules of this polymer include ethene units (usually up to 6% by weight), which are randomly distributed along the polymer chain. Such polymers are characterized by high flexibility and optical transparency, which allows them to be used to obtain transparent products and components with good appearance.

b) In chains block copolymer propylene contains more ethene units (5–15%). Comonomer units are regularly arranged along the polymer chain (in the form of blocks). Due to this regular arrangement of links, the thermoplastic material becomes stronger and less brittle compared to the propylene random copolymer. Such polymers are suitable for applications in which the components need to be given high strength, such as for the industrial sector.

– High impact propylene copolymer(Polypropylene, Impact Copolymer) is a mixture of polypropylene homopolymer and propylene random copolymer. The impact-resistant propylene copolymer contains 45–65% ethylene units. It is used to obtain products with high impact strength. High-impact copolymers are used primarily in the manufacture of packaging, parts for household appliances, films and pipes, as well as in the automotive and electrical appliance industries.

Major suppliers of polypropylene are Borealis, ExxonMobil Chemical, LyondellBasell, SABIC, SIBUR, etc.

Comparison of polypropylene homopolymer and polypropylene copopolymer

Homopolymer polypropylene characterized by high specific strength, rigidity and strength compared to copolymer grades of polypropylene. These properties, combined with high chemical resistance and weldability, allow the material to be used in the production of many corrosion-resistant structures.

Copolymer polypropylene characterized by greater softness, but also higher impact strength, strength and durability compared to propylene homopolymer. The material has higher crack resistance and low temperature strength compared to homopolymer. In all other properties, the homopolymer is slightly superior to the propylene copolymer.

Homopolymer and copolymer grades of polypropylene can be used in almost the same applications. This is because they have many similar properties. Therefore, when choosing a specific grade of polypropylene from the two indicated materials, non-technical criteria very often come to the fore.

Properties and benefits of polypropylene

1. The melting point of polypropylene is:
– homopolymer: 160–165 °C;
– copolymer: 135–159 °C.

2. Polypropylene is one of the lightest polymers of all standard plastics. This feature allows it to be used in the production of lightweight structures.

- Homopolymer: 0.904–0.908 g / cm 3;
- Random copolymer: 0.904–0.908 g / cm 3;
– Impact copolymer: 0.898–0.900 g/cm3.

3. Chemical resistance

– Polypropylene is characterized by very high resistance to dilute and concentrated acids, alcohols and bases.

– Polypropylene has good resistance to aldehydes, esters, aliphatic hydrocarbons, ketones.

– Polypropylene is characterized by limited resistance to aromatic and halogenated hydrocarbons and oxidizing agents.

4. Polypropylene is a highly flammable material.

5. Polypropylene maintains mechanical and dielectric characteristics even at elevated temperatures, in conditions of high humidity and even when immersed in water. Polypropylene is waterproof.

6. Polypropylene is highly resistant to environmental stress cracking.

7. Polypropylene is characterized by low sensitivity to microorganisms (bacteria, fungi, etc.).

8. Polypropylene has good steam sterilization resistance.

To improve the physical and/or mechanical characteristics, polymer additives such as brighteners, fire retardants, glass fibers, mineral fillers, electrically conductive fillers, lubricants, pigments, etc. can be added to polypropylene.

For example: polypropylene is characterized by low resistance to UV radiation, so light stabilizers in the form of hindered amines are often added to it. This allows you to increase the life of the material compared to unmodified polypropylene.

In addition, to increase performance and improve processability, fillers (clay, talc, calcium carbonate, etc.) and reinforcing additives (glass fibers, carbon fibers, etc.) are added to polypropylene.

Due to significant performance improvements (new additives and fillers, as well as new polymerization processes and new blending methods), polypropylene is increasingly viewed not as a cheap material, but as a high performance polymer that can be used as an alternative to traditional engineering plastics, and sometimes even metals (for example, PP grades reinforced with long glass fibers).

Disadvantages of polypropylene

– Poor UV, impact and crack resistance.
– High brittleness at temperatures below -20 °C
– Low maximum operating temperature (90–120 °C)
– Attacked by oxidizing acids, swells rapidly in chlorinated solvents and aromatics
– The resistance to thermal degradation is significantly affected by the presence of material contact with metals
- Change in the dimensions of products after molding due to the course of the crystallization process. This problem can be solved by adding nucleating agents
– Poor paint adhesion

Spheres of application of polypropylene

Polypropylene is widely used in various fields due to its high chemical resistance and good weldability.

1. Packaging production: good barrier properties, high strength, good surface quality and low cost allow the use of polypropylene in the production of packaging.

A) Flexible packaging: PP films have good optical properties and low water vapor permeability, which makes them suitable for food packaging. Polypropylene is also used to produce shrink wrapping films, films for the electronics industry, films for applying graphics, elements of disposable diapers, covers, etc. PP films are obtained either as flat slit films (Cast Film) or as biaxially oriented polypropylene films (BOPP, BOPP).

b) Rigid packing: Containers (boxes), bottles and containers are obtained from polypropylene by blow molding. Thin-walled polypropylene containers are commonly used for food packaging.

2. Consumer goods: polypropylene is used in the production of some components of household appliances and consumer products, in particular transparent parts, household items, furniture, appliances, toys, etc.

3. Automotive: due to low cost, as well as due to good mechanical properties and good processability, polypropylene is widely used in the production of automotive components. The material is used in particular in the production of battery cases, trays, bumpers, side mouldings, interior trim elements, dashboards and door trim elements. Other important properties of PP, which allow it to be used in the automotive industry, are also a low coefficient of linear thermal expansion, low specific gravity, high chemical resistance, good weather resistance, processability and impact strength-to-rigidity ratio.

4. Fibers and fabrics: a large amount of PP is used in the fiber and fabric segment. PP fibers are used in the production of tapes (obtained by cutting films), strips, belts, bulky continuous filaments, staple fibers, spunbond and continuous filaments. Ropes, ropes and twine made of PP have high strength and resistance to moisture, which allows them to be used in shipbuilding.

5. Medicine: Polypropylene is used in the manufacture of various medical devices due to its high chemical and bacterial resistance. In addition, medical PP grades are highly resistant to steam sterilization. Disposable syringes are the most typical medical device made from polypropylene. The material is also used to produce medical test tubes, diagnostic device components, petri dishes, intravenous infusion bottles, sample bottles, food containers, trays, pill containers, etc.

6. Industry: Polypropylene sheets are widely used in the industrial field for the production of acid and chemical containers, sheets, pipes, reusable transport packaging and containers (RTP), etc. This is due to the fact that the material has a high tensile strength, resistance to elevated temperatures and resistance to corrosion.

Comparison of polyethylene and polypropylene

How is polypropylene produced?

Polypropylene was first obtained by polymerization by German chemist Karl Rehn and Italian chemist Giulio Natta. These scientists in 1954 obtained crystalline isotactic polypropylene. After this discovery, very soon, in 1957, polypropylene began to be synthesized on an industrial scale by the Italian company Montecatini.

Syndytactic polypropylene was also first synthesized by Natta and co-workers. Currently, polypropylene is obtained by polymerization of monomeric propene (an unsaturated organic compound with the chemical formula C 3 H 6) in the presence of:

• Ziegler-Natta catalysts;
• metallocene catalysts.

During polymerization, three different chain structures of polypropylene can be formed (depending on the location of the methyl substituents):

• atactic PP (aPP) - disordered arrangement of methyl groups (CH3) along the molecular chain;
• isotactic PP (iPP) - methyl groups are located on one side of the carbon chain;
• syndiotactic PP (sPP) - methyl groups are arranged in an alternating manner relative to the carbon chain.

Polypropylene processing conditions

Polypropylene can be processed into products by almost any processing method. The most typical processing methods for polypropylene are: injection molding, extrusion blow molding, general purpose extrusion.

1. Injection molding

– Mold temperature: 10–80 °C
– When properly stored, the material does not need to be dried before processing
– High mold temperatures increase the gloss level and improve the appearance of the resulting products
– The degree of shrinkage of the material in the mold is from 1.5 to 3%, depending on the processing conditions, the rheological characteristics of the polymer and the wall thickness of the molded product

2. Extrusion(pipes, blown and flat-slit films, insulation for cables and wires, etc.)
– Melt temperature: 200–300 °C
– Material compression ratio: 3:1
– Material cylinder temperature: 180–205 °C
– Pre-drying: not required. Recycled material must be dried for 3 hours at 105-110°C (221-230°F)

3. Blow molding (extrusion followed by blowing)
4. Compression molding (pressing)
5. Rotational molding
6. Injection blow molding
7. Extrusion blow molding
8. Oriented injection blow molding
9. General purpose extrusion

Expanded polypropylene (EPP) can also be produced using a special process. The material is well processed by injection molding, and it is widely used in both batch and continuous processes.

Polypropylene recycling

All plastics are assigned a "Polymer Identification Code/Plastics Recycling Code" based on the type of polymer they use. Polypropylene has an identification code - 5.

Polypropylene completely 100% can be recycled (recycled). Examples of products made from recycled polypropylene (r-PP): car battery cases, signal lights, battery cables, brooms, brushes, ice scrapers, etc.

The polypropylene recycling process typically includes a step to melt the waste plastics at 250°C to remove impurities from the material, a subsequent step to remove the remaining molecules under vacuum, and a solidification step at about 140°C. This recycled polypropylene can be mixed with virgin polypropylene up to 50%. The main problem of polypropylene recycling is related to the large volume of consumption of this polymer. For example, only about 1% of used PP bottles are currently recycled. In comparison, 98% of used bottles made from and are currently recycled.

Polypropylene is a safe material because it does not have a significant impact on human health and does not have a chemical or toxic effect on it.

Polypropylene: performance characteristics

Polypropylene is one of the most versatile polymers used and has high mechanical properties.

Polypropylene also has good chemical resistance and heat resistance. Some of these characteristics have allowed polypropylene to displace polyethylene from some applications. By studying all the properties of polypropylene, in particular mechanical, electrical and chemical characteristics, it is possible to choose the right material for a particular application.

Polypropylene is a light, crystallizing material that is produced in the form of a white powder or granules having a bulk density of 0.4-0.5 grams per cubic centimeter.

Polypropylene is of several types:

• polypropylene homopolymer (PP HO)
• metallocene polypropylene (mPP)
• block copolymer of propylene with ethylene, or copolymer (PPCP)
• random copolymer of polypropylene (PP random copolymer)

Polypropylene homopolymer (PP HO)

Homopolymer- polypropylene, in which the macromolecules contain the same monomer units. It is a fairly hard polymer with high flexural strength.

The most common method of modifying a polypropylene homopolymer is to make it antistatic using special antistatic additives. These additives prevent dust from adhering to products made from this material. Thanks to the introduction of such additives as nucleators, the homopolymer becomes transparent, which makes it possible to significantly expand the range of products made from this type of polypropylene. A typical polypropylene homopolymer is cellulose. However, the homopolymer, which has increased rigidity and transparency, is quite brittle at low temperatures.

The introduction of flame retardant additives imparts fire resistance to the homopolymer and significantly expands the scope of its application. The most typical field of application for flame retardant polypropylene is electrical engineering.

Polypropylene homopolymer is quite easy to process, with the introduction of certain additives (recyclate), the physical and mechanical properties of polypropylene do not change.

Metallocene polypropylene (mPP)

Metallocene polypropylene obtained by polymerization with metallocene catalysts. Such polymerization does very interesting things with the polymer, for example, polypropylene with completely different tacticity can be obtained.

Using the special metallocene catalysts, polypropylene is obtained, which contains both atactic and isotactic blocks in one macromolecule. Such a polymer resembles rubber, being an excellent elastomer, and all this is due to the fact that isotactic blocks form crystals on their own.

Block copolymer of propylene with ethylene, or copolymer (PPCP)

Block copolymer of propylene with ethylene (copolymer) was synthesized in the late fifties. Now it is obtained almost everywhere where polypropylene (PP) is produced, and in recent years the technology for the synthesis of BS has improved significantly.

A block copolymer is a chain of propylene molecules interrupted by an ethylene-propylene copolymer chain. Its production requires a second reactor.

Block copolymers of propylene with ethylene are produced in the form of granules uniform in color. They have: high impact strength (at low temperatures) and high elasticity; increased long-term thermal stability; resistance to thermal-oxidative destruction during the production and processing of polypropylene, as well as during the operation of a product made of it.

Due to the crystal structure, the polypropylene block copolymer is a fairly economical structural thermoplastic used for the production of body parts for office equipment, household and electrical appliances, as well as in the automotive industry (bumper housings, batteries, etc.). Along with this, BS is widely used in the production of consumer goods - garden and office furniture, disposable tableware, thin-walled and industrial containers, packaging for frozen foods, toys, and medical products.

Polypropylene block copolymer has the following properties:

• Climatic and chemical resistance: at high temperatures - to alkalis, acids, salt solutions, vegetable and mineral oils; at room temperature - to organic solvents; BS has low moisture absorption. Due to these properties, all products made from this material can be sterilized, stay in liquid aggressive environments for a long time and are completely harmless in contact with products.
• Temperature range: max temperature - up to one hundred and forty degrees, melting point - one hundred and seventy degrees. The block copolymer is frost-resistant (modified grades are operated at temperatures below minus forty degrees, unmodified grades - up to minus thirty degrees)
• Electrical insulation: some brands have an electrical strength of more than one hundred kV / mm.
• Mechanical properties: block copolymer has significant impact resistance, reduced hardness and stiffness, increased wear resistance.

The most common method of modifying a polypropylene block copolymer is to make it antistatic using special antistatic additives. These additives prevent dust from adhering to products made from this material. Thanks to the introduction of such additives as nucleators, the BS becomes transparent, which makes it possible to significantly expand the range of products made from this type of polypropylene.

The introduction of flame retardant additives gives BS fire resistance and significantly expands the scope of its application. The most typical field of application for flame retardant polypropylene is electrical engineering.

BS polypropylene is quite easy to process, with the introduction of certain additives (recyclate), the physical and mechanical properties of polypropylene do not change.

PP random copolymer

Polypropylene Random Copolymer has a crystalline structure. There are two varieties of random copolymer - transparent and opaque Transparent - used for making thin-walled food packaging material, laminating films, sheets.
Opaque - used for the production of pipes and fittings for hot water systems.

Polypropylene random copolymer has the following properties:

• Climatic and chemical resistance: at high temperatures - to alkalis, acids, salt solutions, vegetable and mineral oils; at room temperature - to organic solvents; has low moisture absorption. Due to these properties, all products made of this material can stay in liquid aggressive environments for a long time and are completely harmless in contact with products.
• Temperature range: max temperature - up to one hundred and forty degrees, melting point - one hundred and seventy degrees.
• Electrical Insulation: Polypropylene stat copolymer has good electrical insulating properties, but worse than homopolymer and block copolymer.
• Mechanical properties: stat copolymer is between homopolymer and block copolymer in terms of stiffness and impact resistance.

The statistical copolymer of polypropylene is quite simple to process, with the introduction of certain additives (recyclate), the physical and mechanical properties of polypropylene do not change.

All types of polypropylene are characterized by excellent wear resistance and are suitable for recycling.