Polyethylene English name: polyethylene, referred to as PE, is a thermoplastic resin obtained by polymerization of ethylene. In industry, it also includes copolymers of ethylene with small amounts of α-olefins. Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance (the minimum use temperature can reach -70~-100 °C), good chemical stability, can resist most acids and alkalis (not resistant to acids with oxidizing properties), insoluble in general solvents at room temperature, small water absorption, excellent electrical insulation performance.

Polyethylene is a crystalline thermoplastic resin. Their chemical structure, molecular weight, degree of polymerization and other properties are highly dependent on the polymerization method used. The aggregation method determines the type and degree of branching. The degree of crystallinity depends on the degree of regularity of the molecular chain of the piece and the thermal history it has experienced.

Polyethylene is sensitive to environmental stresses (chemical and mechanical actions) and has less resistance to heat aging than polymer chemical structures and processing strips. The properties of polyethylene vary from variety to variety, mainly depending on the molecular structure and density. Different production methods can be used to obtain products with different densities (0.91~0.96g/cm^3;). Polyethylene can be processed by molding methods of general thermoplastics (see plastic processing). It is widely used in the manufacture of films, packaging materials, containers, pipes, monofilament, wires and cables, daily necessities, Polyethylene rope, etc., and can be used as high-frequency insulation materials for TVs and radars. With the development of petrochemical industry, polyethylene production has developed rapidly, and the output accounts for about 1/4 of the total output of plastics. In 1983, the world's total polyethylene production capacity was 24.65Mt, and the capacity of installations under construction was 3.16Mt. According to the latest statistics in 2011, the global production capacity reached 96Mt, and the current development trend shows that production and consumption are gradually shifting to Asia, and China is increasingly becoming the most important consumer market.

　　Polyethylene structure

Polyethylene (PE) plastic, the convenience bag we often mention is polyethylene (PE), and the rope we use every day Polyethylene rope. Polyethylene is the simplest polymer and the most widely used polymer material. It is made up of repeating –CH2– units connected. Polyethylene is formed by the addition polymerization of ethylene (CH2=CH2).

The properties of polyethylene depend on how it is polymerized. High-density polyethylene (HDPE) is produced by Ziegler-Natta polymerization under medium-pressure (15-30 atm) organic compound catalytic conditions. Under these conditions, the polymerized polyethylene molecules are linear, and the molecular chains are very long, and the molecular weight is as high as hundreds of thousands. If the radical polymerization is under high pressure (100-300MPa), high temperature (190–210C), peroxide catalyzed conditions, the production is low-density polyethylene (LDPE), which is branched chain compounded structure. One of the technical products.