High density polyethylene (HDPE) is a white powder or granular product. Non toxic, odorless, with a crystallinity of 80% to 90%, a softening point of 125-135 ℃, and a usage temperature of up to 100 ℃; Hardness, tensile strength, and creep resistance are superior to low-density polyethylene; Good wear resistance, electrical insulation, toughness, and cold resistance; Good chemical stability, insoluble in any organic solvent at room temperature, resistant to corrosion by acids, alkalis, and various salts; The film has low permeability to water vapor and air, and low water absorption; The aging resistance is poor, and the environmental stress cracking resistance is not as good as low-density polyethylene. Especially, thermal oxidation can cause its performance to decline. Therefore, antioxidants and UV absorbers need to be added to the resin to improve this deficiency. High density polyethylene film has a lower thermal deformation temperature under stress, so attention should be paid when applying it.

Development History

A revolutionary progress has occurred in the field of pipelines in this century, which is to replace steel with plastic. With the rapid progress of polymer materials science and technology, the deepening of the development and utilization of plastic pipes, and the continuous improvement of production processes, plastic pipes fully demonstrate their excellent performance. Today, plastic pipes are no longer mistaken by people as "cheap substitutes" for metal pipes. In this revolution, polyethylene pipelines were highly favored and increasingly shone brightly. They were widely used in gas transportation, water supply, sewage treatment, agricultural irrigation, fine particle solid transportation in mines, as well as in fields such as oil fields, chemical engineering, and postal and telecommunications. Especially in gas transportation, they were widely used.

HDPE is a thermoplastic polyolefin produced by ethylene copolymerization. Although HDPE was introduced in 1956, this plastic has not yet reached a mature level. This universal material is still constantly developing new applications and markets.

As of the end of 2006, there were four sets of high-density polyethylene units belonging to China National Petroleum Corporation (CNPC), including Lanzhou Petrochemical High Density Polyethylene Unit, Daqing Petrochemical High Density Polyethylene Unit, Liaoyang Petrochemical High Density Polyethylene Unit, and Jilin Petrochemical High Density Polyethylene Unit.

High density polyethylene is usually manufactured using the Ziegler Natta polymerization method, which is characterized by the absence of branched chains on the molecular chains, resulting in a regular arrangement of molecular chains and high density. This process uses ethylene as the raw material and oxygen or organic peroxides as initiators to initiate polymerization reactions in tubular or kettle low-pressure reactors.

High density ethylene is an environmentally friendly material that can be recycled and reused when heated to its melting point. Note that plastic raw materials can be divided into two categories: "Thermoplastic" and "Thermosetting". "Thermosetting plastic" becomes a solidified state after being heated to a certain temperature, and even further heating cannot change its state. Therefore, products with environmental issues are "thermosetting plastic" products (such as tires), not "thermoplastic" products (such as plastic pallets note: pallets are called "clamps" in Hong Kong and Macao), so not all "plastics" are not environmentally friendly.