Polyethylene is a thermoplastic used in a wide variety of products. Taken the name from Monomer ethylene, polyethylene is produced using ethylene. In plastic industry in general, the name is used briefly as PE. The ethylene molecule C2H4 consists essentially of two CH2 linked by a double bond.
(CH2=CH2) the production of polyethylene, occurs by Polymerisation of ethylene. it can be polymerization method, Radical polymerization, anionic polymerization and with Ion coordination polymerization and cationic polymerization methods. Each of these methods provides different types of polyethylene production.
Although the features vary by type; good resistance to outdoor conditions and moisture, flexibility, poor mechanical strength and superior chemical resistance countable as general features. Has a very common usage area, as containers, plastic boxes, kitchenware, coatings, pipes and tubes, toys, insulating layers in cables, packing and packaging films.
Types of Polyethylene:
High density Polyethylene (HDPE):
High density Polyethylene is the close kind to chemically pure Polyethylene. Contains unbranched Molecules with very few imperfections that degrade such line drawing.
Crystallization can be achieved at a high level, although small defects obtainable at a very low level and as a result high density polyethylene is obtained.
In some polyethylene plastics a secondary polymerization is carried out at low alkene concentrations to increase the degree of crystallization.
The density of high density polyethylene is approximately between as 0.94 to 0.97 g / cm3
When the branching is too low high density polyethylene also called linear polyethylene.
Low Density Polyethylene (LDPE):
The reason why it is called low density polyethylene in the crystallization process, it is the formation of polymer structure containing durable branches that reduce density. Branching, ethyl and butyl groups primarily includes. Long chain branches, occurs at random intervals in the long main chain.
On average, the density of low density polyethylene is between as 0.90 and 0.94 g / cm3.
Linear Low Density Polyethylene(LLDPE):
The linear polyethylene group attached to the short Alkali groups at random intervals on the main line. This substance secondary polymerization with an ethylene aklene as a result.
On average the density is between 0.90 and 0.94 g / cm3.
· HDPE High Density Polyethylene