In this century, a revolutionary progress has taken place in the field of pipeline, that is, "replacing steel with plastics". With the rapid development of polymer materials science and technology, the deepening of the development and utilization of plastic pipes, and the continuous improvement of production technology, plastic pipes show their outstanding performance incisively and vividly. Today, plastic pipes are no longer mistaken as "cheap substitutes" for metal pipes. In this revolution, polyethylene pipeline is favored by many people, which is increasingly shining. It is widely used in gas transportation, water supply, sewage, agricultural irrigation, fine particle solid transportation in mines, oil fields, chemical industry, post and telecommunications and other fields, especially in gas transportation.
HDPE is a thermoplastic polyolefin produced by ethylene copolymerization. Although HDPE was launched in 1956, it has not reached the mature level. This kind of general material is still developing its new use and market.
China's domestic producers of HDPE (HDPE here does not include HDPE produced by HDPE Plant) include CNPC, Sinopec and CNOOC. As of the end of 2006, there are four sets of HDPE plants belonging to CNPC, namely, Lanzhou Petrochemical HDPE Plant, Daqing Petrochemical HDPE Plant and Liaoyang Petrochemical Petrochemical HDPE Plant, Jilin Petrochemical HDPE Plant.
High density polyethylene (HDPE) is usually produced by Ziegler Natta polymerization, which is characterized by no branched chain on the molecular chain, so the molecular chain arrangement is regular and has high density. In this process, ethylene was used as raw material and oxygen or organic peroxide as initiator to initiate polymerization in tubular or kettle type low-pressure reactor.
High density ethylene is a kind of environmental protection material. It can be recycled after heating to the melting point. Note: plastic raw materials can be divided into two categories: "thermoplastic" and "thermosetting". Thermosetting plastic "is a product that changes into a curing state after being heated to a certain temperature, even if it continues to be heated, it cannot change its state. Therefore, products with environmental protection problems are" thermosetting plastic "products (such as tires), not" thermoplastic " Plastic products (such as plastic pallet note: pallet is called "plywood" in Hong Kong and Macao), so not all "plastic" are not environmentally friendly.