The structure of polyethylene LDPE consists of a large number of branches of various lengths. They do not allow molecules of high molecular weight to form a crystalline structure. Such a structure has weak intermolecular bonds, which gives polyethylene a low resistance to ruptures, a high degree of plasticity, and increased melt flow.

The material for processing by the method of polymerization are granules up to 5 mm.

LDPE can be formed in tubular or autoclaved reactors under the following conditions: temperature range of 200–260 ° C; pressure indicators 150–300 MPa; the presence of an initiator in the form of oxygen or peroxide of organic origin. The material obtained as a result of the reaction by the radical mechanism has a molecular weight of 80–500 thousand and crystallinity of 50–60%. The polymer in the liquid state is subjected to melt granulation. The extrusion method allows LDPE to be processed in two main ways: by blowing into tubular film; into a flat film through a cooled roller using a flat-slot head.

Basic properties

LDPE macromolecules differ in the content of C1 – C4 side hydrocarbon chains. When laid parallel to each other, they form lamellae. A large number of side branches gives the material a low crystallinity and density. By its physical properties, LDPE is brilliant, smooth, elastic, and highly elastic. For LDPE at 20 °, the following physicochemical properties are characteristic:

density up to 0.93 g / cm²;
destruction at stretching up to 170 kgf / cm²;
static bending destruction up to 170 kgf / cm²;
destruction at cutting up to 170 kgf / cm²;
relative elongation at break of 500–600%;
flexural modulus up to 2600 kgf / cm²;
yield strength at stretching up to 160 kgf / cm²;
relative lengthening at the beginning of the current 15–20%;
Brinell hardness 1.4–2.5 kgf / mm².

Industrial applications

LDPE is successfully used for the manufacture of bags with a loop handle, as well as a cutting handle. The brilliance of LDPE makes the image on such products bright, and the color gamut is very juicy.

Packages made of LDPE are distinguished by their ability to keep their shape well and hardly wrinkle. High strength allows the use of such packages for storage and transportation of objects with sharp and cutting corners.

A large number of positive characteristics have made products from LDPE most demanded for the production of image brand packages. Gift wrapping at major and prestigious events is also produced in products manufactured from LDPE. Films for wrapping, containers and plastic bags are made from such polyethylene, they are distinguished by their beauty, effective gloss and withstand about 4 kg of weight. The low crystallinity of LDPE gives this polymer flexibility and softness. It is plastic and slightly waxy to the touch. Widespread use and demand are based on high strength LDPD-made products. The starting material has good resistance to breaks and impacts. It is durable and easily withstands low temperatures, multiple compression and stretching. In addition, HP polyethylene is non-toxic. Its use is safe for humans, animals and the environment. Main applications of LDPE: film extrusion; cable production; the production of plastics under pressure; production of blown products.

Recycling features

There are physical and chemical, as well as mechanical processing methods.
The mechanical method is grinding to produce powdered materials and chips for use in injection molding. It is characterized by an almost absolute absence of changes in physicochemical properties.
The physicochemical method of processing involves: destruction followed by the production of monomers and oligomers that are suitable for the production of fibers and films; secondary melting followed by the preparation of a granulate, agglomerate.
Extrusion and injection molding; reprecipitation from solutions with the subsequent development of powder formulations used for coatings and the production of composite components; chemical modification to produce materials with new properties.

Given that the introduction of new installations is not predicted, and the number of buyers in this segment has stable indicators, the LDPE market expects stability in the area of ​​supply and demand.