What is polyethylene?

Polyethylene is a type of thermoplastic polymer, which means that this material becomes liquid when it reaches its melting point and solid when it reaches the freezing point. Polyethylene is the chemical synthesis of ethylene, which is usually formed from a combination of natural gases and crude oil. Its informal names are polythene or polyethylene and it is also called PE for short. This material is often used to make plastic compounds to be used in pure form. This material can be used in a wide range of different uses. Polyethylenes are a family of thermoplastics obtained by polymerization of ethylene gas (C2H4).

Through the catalyst and polymerization method of this material, various properties such as density, melt flow index (MFI), crystallinity, degree of branching and crosslinking, molecular weight and molecular weight distribution can be controlled in them. Low molecular weight polymers are used as lubricants. Medium molecular weight polymers are miscible waxes with paraffin, and finally polymers with a molecular weight of more than 6,000 have the highest consumption in the plastics industry. Polyethylene has a very simple structure, so it is simpler than all commercial polymers. A polyethylene molecule is a long chain of carbon atoms with two hydrogen atoms attached to each carbon atom.

Polyethylene and its types

Ethylenes are classified based on their density, which is related to the amount of density, the size of the polymer chain and the type and number of branches in the chain. The basic division of polyethylene is as follows:

• High density LDPE
  High density HDPE
  LLDPE linear style
  Very light VLDPE
  Very high molecular weight UHMWPE
  Ethylene – vinyl ester copolymers
  IONIMERS IONOMERS
  With PEX width fittings
  Heat resistant PERT

Lightweight or LDPE type

Lightweight polyethylene has a branched chain. Therefore (LDPE) chains can not bond well together and have weak intermolecular strength and lower tensile strength. Lightweight polyethylene is usually produced by radical polymerization. The properties of lightweight polyethylene include flexibility and the possibility of degradation by microorganisms. Polyethylene has a low density in terms of low and low molecular density, which increases its flexibility, which has led to more than fifty percent of the production of this product in the manufacture of films and sheets for use in transparent gloss coatings. Consume packing liners, covers and suitcases. This type of polymer is also used to make containers such as pressurized bottles.

Heavy type or HDPE

This type of polyethylene has a branchless polymer chain. Heavy-duty polyethylene is a white, opaque solid that forms brittle films. These polymers are very crystalline (70-80%) and their melting point is about 130 degrees Celsius. Density is commonly used as a measure of the crystal content of alkyls such as alpha-olefins (α) including butene, hexene, and octone as a comonomer during polymerization. In this case, short branches are formed along the main polymer chain.

These small branches reduce the crystallinity and hardness of the polymer. And it must be said that the most common and most widely used and perhaps the first type of plastic to be produced is the heavy type (HDPE). The molecular chain in this type of polymer is compact, which increases its density. Therefore, flexibility is greatly reduced. Although this type of polymer has less impact resistance than lightweight polyethylene, its resistance to chemicals is as good as its resistance to brittle environmental stresses.

Heavy polyethylene is initially homogeneous, pure and opaque, not colored, and pigments are added if necessary. These materials are used in white, red, blue, yellow, green, black and sometimes even the color of their raw materials. They are electrical insulators and will be destroyed by direct heat. From the types of heavy polyethylene production materials, we can supply water, sewage and industrial polyethylene pipes, make toys, sports equipment, heavy polyethylene film, mineral water containers and household drinks. . . Named.

Linear style type or LLDPE

Linear lightweight polyethylene has a lower density even less than its lightweight type, but instead has good tensile strength against punctures and tears. Due to its extraordinary properties, linear lightweight polyethylene is considered by various industries today, including in the manufacture of polyethylene pipes for agriculture and irrigation pipes, the production of photographic films, fibers and the production of various plastic appliances used in the kitchen and food industries. has taken.