Low-pressure polyethylene, a type of polyethylene (PE) plastic, is commonly used in convenient bags. Polyethylene is the simplest polymer and the most widely used polymer material. It is made up of repeated 每CH2每 units. Polyethylene is made by addition polymerization of ethylene (CH2=CH2). The performance of polyethylene depends on its polymerization method. High-density polyethylene (HDPE) is formed by Ziegler-Natta polymerization under medium pressure (15-30 atmospheres) and organic compound catalysis. The polyethylene molecules polymerized under this condition are linear, with long molecular chains and molecular weights of up to hundreds of thousands. If it is free radical polymerization under high pressure (100-300MPa), high temperature (190每210C), and peroxide catalysis, low-density polyethylene (LDPE) is produced, which has a branched structure.

Physical and chemical properties

Properties Odorless, tasteless, non-toxic white granules or powders. Melting point 131⊥. Density 0.910-0.925g/cm3. Softening point 120-125⊥. Brittle temperature -70⊥. Maximum use temperature 100⊥. Excellent heat resistance, cold resistance, wear resistance, dielectric properties and chemical stability. Almost insoluble in any organic solvent at room temperature. Resistant to corrosion by various acids, alkalis and various salt solutions. Low water absorption and water vapor permeability. But poor aging resistance.

Tensile yield strength (MPa) ˇ23.0

Brittle temperature (low temperature impact, ⊥) ˉ-70

Volume resistivity (次cm) 1℅10

Dielectric strength (kV/mm) ˇ35

Dielectric constant 2.35

Dielectric loss tangent ˉ5℅10

Production method

Mainly adopts mud method. In the presence of catalysts titanium tetrachloride and diethylaluminum monochloride, the pressure is controlled to be 〃1-5)℅10Pa, the temperature is 65-75⊥, and more than 99% of ethylene is polymerized in solvent gasoline to obtain a slurry, which is then obtained through alcoholysis, neutralization, water washing, drying and granulation.

Application fields

It is used in the pharmaceutical and chemical industries to manufacture hollow products such as barrels, bottles and storage tanks. It is used in the food industry to manufacture packaging containers. It is used in the machinery industry to manufacture general mechanical parts such as covers, handles, hand wheels, and the paper industry to manufacture synthetic paper. It is used in agriculture to manufacture covering films. It is used in the electrical industry to manufacture cable insulation and electrical parts. It is used in the fishery industry to manufacture fishing nets. It is used in the petroleum industry to manufacture water pipes and acid, alkali, salt and other solution delivery pipes.

Raw materials

Polyethylene, the English name of polyethylene: polyethylene, referred to as PE, is a thermoplastic resin obtained by polymerization of ethylene. In industry, it also includes copolymers of ethylene and a small amount of 汐-olefins. Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance (the lowest operating temperature can reach -70‵-100⊥), good chemical stability, can withstand most acid and alkali erosion (not resistant to oxidizing acids), is insoluble in general solvents at room temperature, has low water absorption, and has excellent electrical insulation properties.

High-pressure comparison

High-pressure polyethylene (PEF) is a product that adopts advanced foaming technology production lines and the most advanced scientific formula. It is blended with high-pressure polyethylene, flame retardants, foaming agents, cross-linking agents and other raw materials. After mixing and refining, polyethylene hydrocarbons are foamed at a high rate through chemical bridging to form a network polymer structure and balanced open-cell bubbles.

High-pressure polyethylene has a low density and a low melting temperature.

High-pressure polyethylene: More than half is used for film products, followed by pipes, injection molded products, wire wrapping layers, etc.

Medium and low-pressure polyethylene: mainly injection molded products and hollow products.

Ultra-high pressure polyethylene: Due to its excellent comprehensive properties, ultra-high molecular weight polyethylene can be used as an engineering plastic.

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