High density low pressure polyethylene: characteristics, description, application

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

High density polyethylene - what is it? Low pressure polyethylene (HDPE for short) and high density is a material that belongs to the group of thermoplastic polymers. This raw material is distinguished by such qualities as strength, ductility and durability. Due to its positive qualities, this type of product has found its application in the creation of many types of products.

Material description

High density low pressure polyethylene is a substance that is obtained by polymerization of ethylene hydrocarbon. It turns out at low pressure, hence the name. Various substances may be involved in the process, and the temperature may also change. By changing these characteristics, you can get HDPE with different densities.

Besides, they will differ in some properties. During the production process, high-density low-pressure polyethylene is marked, in accordance with the highestindex PE-80 or PE-100. The difference between these brands is insignificant, but it is. The difference lies in the following parameters:

• Hardness.
• Tear and tensile strength.
• Resistant to all kinds of mechanical damage, as well as deformations.
• Temperature at which the product can be operated, etc.

Structure of material

No matter what technology was used for production, high density polyethylene will always have a linear internal structure. In other words, the structure of this substance will consist of polymeric macromolecules with a large number of bonds. There will also be random intermolecular bonds.

It is important to add here that the cost of finished products of this type is quite low. The thing is that manufacturing takes place on equipment that is not very expensive, the raw materials for this also need to be cheap, and a team of workers, in which there are only up to two dozen people, can maintain the equipment and monitor the process. For example, one workshop is enough to successfully manufacture HDPE pipes.

Key Features

In the manufacture of this product, all manufacturers must be guided by the state standard document 16338-85. This document contains all the basic technical requirements that the finished product must meet. Among these features are the followingOptions:

• The density of the finished film should be between 930 and 970 kg/m3.
• The material begins to melt at temperatures from +125-135 degrees Celsius.
• The minimum temperature at which the material will be as fragile as possible is -60 degrees Celsius.
• Tear and tensile strength should reach 20-50 MPa.
• Products should take about 100 years to decompose naturally.
• If all the manufacturing rules are followed, the characteristics of low-pressure polyethylene allow it to be used from 50 to 70 years or more.

Issue of different brands

Basic types of ND polyethylene are produced in powder form. Compositions of this material can be supplied in the form of colored or uncolored granules. Raw materials of a granular type, which are subsequently used to create different products, should have particle sizes from 2 to 5 mm in diameter, while their shape should be identical. Product varieties may vary. It can be top, first or second grade.

Low pressure polyethylene, what is it? This is a raw material, using which, it is possible to obtain sufficiently rigid and solid components. These properties can be seen even if it is made into a thin film.

The best performance of HDPE (in terms of chemistry and physics) is the tensile strength, which is approximately 20 to 50 MPa. The second best material quality is elongation, which ranges from 700 to 1000%. The appearance of this film is sufficientinconspicuous, it is hard, and when touched creates a rustling. The smooth surface structure is usually not preserved.

Good qualities of film

If all the specifications according to GOST 16338-85 for low-density polyethylene have been met, then this material has the following advantages:

• With respect to temperature limits, there is high resistance to cracking/scratching, etc.
• Chemical and biological inertness, which manifests itself in the fact that the film is not afraid of exposure to chemically active substances, as well as microorganisms.
• Resistant to radiation radiation, excellent performance and as a dielectric.
• May be a good insulator for liquid or gaseous media.
• For humans, as well as for the environment, the material is completely safe, non-toxic.

It is worth noting that high-density low-pressure polyethylene according to GOST 16338-85, due to its properties, can be used for waterproofing purposes, as a raw material for the production of gas pipes. Due to its inertness to many environmental components, polyethylene is perfect as a starting material for the production of containers used as accumulators of environmentally harmful substances.

Negative properties

Like any other material, HDPE is not without flaws. This substance belongs to that group of polymers-thermoplastics, which, despite all their strength and great resistance to various kinds of negative influences, has the following negative characteristics:

• If the temperature exceeds the allowable norm, then the material quickly starts to melt.
• Raw materials are prone to aging if constantly exposed to sunlight, which is rich in ultraviolet light.

Although it would be fair to note here that the last drawback can be eliminated if a special coating is used for polyethylene structures. In addition, there is an operation that is carried out at the stage of manufacturing the product. Protective agents are introduced into the structure of the substance to prevent aging.

Snolen - high density low pressure polyethylene

Snolen is a brand of HDPE, which is produced by such an enterprise as OAO Gazprom Neftekhim Salavat. The company is one of the largest in the Russian market.

The main characteristics of the product manufactured by this enterprise are as follows:

• High resistance to s alts, alkalis, and oils of mineral and vegetable origin.
• Inertness to biological types of stimuli.
• Recyclable product.
• The level of moisture absorption is quite low.
• Minimum freezing temperature threshold increased to -80 degrees Celsius;
• High electrical insulation properties.

Varieties of raw materials

High density low pressure polyethylene Snolen is divided into several types depending on the technology used to make it.

Snolen EV 0, 41/53 is made by extrusion blow molding. The main purpose of this type of raw material is the manufacture of pipes used for the installation of water pipes in homes and industries. Product diameter may vary. Also used in the automotive industry. Used for the production of bags of filling type.

Another type of high-density low pressure polyethylene according to GOST 16338-85 is Snolen IM 26/64 and Snolen IM 26/59. These two types belong to injection molded product varieties. The method is used to create things like traffic cones, containers, crates, buckets. The main area of use is economic activity and the food industry.

Snolen is a type of low pressure polyethylene that can be processed by cutting, welding, casting, pressing.

Other product types

The company is engaged in the production of products such as Snolen EF 0, 33/51 and Snolen EF 0, 33/58. These marks belong to film types. The main application of the products is the production of thick and thin film. Most often, the film is used as packaging for various types of goods. Plastic bags are also made from the same brand.

Snolen 0, 26/51 - grade of polyethylene, which is used for the manufacture of pipes. Most often theyare used for the installation of gas pipelines, as well as for water pipes, which can be used for both cold and hot water. Pipes may vary in diameter and color. In addition, these products are successfully used in the chemical industry.

High density low pressure polyethylene P-Y342 (Shurtan GCC TU), GOST 16338-85

Simplex is another company that produces polyethylene for tubular products.

P-Y342 is the main grade used for pipe production. As for the technical characteristics of this product, it is very similar to a brand such as PE-80. The main parameters of this polyethylene are as follows:

• Density is from 0.940 to 0.944g/cm3.
• The number of different inclusions included in the product does not exceed 5 units.
• The mass fraction of volatile substances in the composition does not exceed 0.05%.
• Tensile yield strength is not more than 16 MPa.
• Elongation at break is 750%.

Besides grade 342, the company also produces grades 337 and 456 with high specifications.

Stavrolen LLC is also involved in the production of products 277-73. High-density low pressure polyethylene from this manufacturer is characterized by resistance to thermal oxidative aging. The materials combine sufficiently high stiffness with low warpage readings. They have a good gloss finish. The main direction of use is the production of homedishes, caps for aerosols, medical syringes and other items. For the production of products, the casting method is used.

GOST safety

In addition to describing the basic technical requirements that polyethylene must meet, the document also indicates some safety rules.

Polyethylene base grades at room temperature in the room should not emit toxic volatile substances. In addition, its surface must be safe for human skin. When working with such material, there is no need to use personal protective equipment. If the work is done with polyethylene powder, then it is already necessary to use protective equipment for the lungs. In particular, a universal respirator brand RU-60M is used. If the product is heated above 140 degrees Celsius, then polyethylene begins to emit harmful volatile substances. These include carbon monoxide. It is possible to carry out the process of processing polyethylene only in those industrial premises in which there is good ventilation. In this case, the frequency of air exchange in the room should be at least 8. If exchange ventilation is installed, then the air replacement rate should be equal to 0.5 m/s. If exhaust ventilation is installed, the parameter increases to 2 m/s.

Additional information

The supply of low-pressure polyethylene is carried out in batches. As a batch, the presence of polyethylene of one brand and one grade is considered, if its quantity is not less than 1 ton. In addition, the partymust have a quality certificate, in which you need to indicate the name and trademark of the manufacturer, symbol, as well as the type of product, date of manufacture, batch number and net weight. Upon acceptance, tests are also carried out to determine the quality of the goods. If at least one of the items received unsatisfactory results, then you need to check again, while doubling the number of the first sample. The results of such a check will apply to the entire batch of goods.