Cross-linked polyethylene: application and characteristics

Polyethylene is a material that is used in various sectors of the economy. Products from it are also used in everyday life. The conventional polyethylene retains its strength to a temperature of 130 degrees. However, often it is necessary to use this material under more severe conditions, with a higher temperature regime and pressure, for example, in heating and hot water supply systems.

This need led to the search for ways to produce a more durable material. The technology found made it possible to obtain cross-linked polyethylene, which has a higher molecular weight than the conventional material and has improved characteristics. By stitching is understood a process in which the links of molecules due to the formation of transverse bonds are joined into a three-dimensional wide-mesh net.

Depending on the applied effect, chemical and physical cross-links are distinguished. In the latter case, pipes (cross-linked polyethylene used to create these products) are irradiated with X-ray hard rays. This technology is very productive, and in a minute you can get up to 80 meters of material.

The disadvantage of the method lies in the fact that the crosslinked polyethylene has a nonuniformity in the thickness of the pipe. At the inner side, the lowest percentage of the molecules is obtained, while the outer side has the highest percentage. Accordingly, the properties of the product in the volume vary. The result is a cross-linked polyethylene of category C (PEH).

When using a chemical method to replace hydrogen atoms in molecules, a special silane substance is used. Accordingly, a silane crosslinked polyethylene is produced. Pipes during production pass through a special bath filled with a substance. That allows to make uniform process of cross-linking from the internal and external surfaces deep into the walls of the pipe. This technology makes it possible to obtain pipes with a high percentage of processing, and the material is designated PEH-B.

There is a procedure for treating polyethylene with nitric radicals, the resulting material is labeled PEH-D. However, this technology is not used because of low efficiency.

Also perform crosslinking with peroxides. In this case, the manufacturing process involves mixing peroxide and polyethylene, after which a cross-linked polyethylene of the PEX-A group is produced in a molten state and under the influence of a high temperature.

Pipes made of materials (groups B, C) are used for water supply and heating, however, they have a number of limitations, which are related to the strength and plasticity of products.

The most successful pipes are made of Group A polyethylene, they have high fatigue strength, crack resistance, shape stability, flexibility, and endurance to impacts.

Heating pipes made of cross-linked polyethylene are widely used for individual, civil and industrial construction. With their help they carry out floor-to-ceiling radiator wiring and create underfloor heating systems.