Polyethylene (abbreviated as PE) is one of the most commonly used plastics in daily life. It is widely used in the manufacture of plastic bags, films, barrels and other products. It is also the main type of plastic waste on the earth.
Polyethylene can be considered transparent in the film state, but when it exists in block form, it will have strong light scattering and become opaque due to the large number of crystals inside. The degree of crystallization of polyethylene is affected by the number of its branches. The more branches, the more difficult it is to crystallize. The melting temperature of polyethylene crystals is also affected by the number of branches, ranging from 90 degrees Celsius to 130 degrees Celsius. The more branches, the lower the melting temperature. Polyethylene single crystals can usually be prepared by dissolving high-density polyethylene in xylene above 130 degrees Celsius.
Polyethylene is classified according to its density and branching. Its mechanical properties depend significantly on variables such as the degree and type of branching, crystal structure and molecular weight.
There are several types of polyethylene:
UHMWPE (Ultra High Molecular Weight Polyethylene)
ULMWPE (Ultra Low Molecular Weight Polyethylene or PE-WAX, Polyethylene wax)
HMWPE (High Molecular Weight Polyethylene)
HDPE (High Density Polyethylene) is also called low-pressure polyethylene. Because it is produced under low pressure, it contains more long chains and has a high density. It is mainly used to make various injection molding, blow molding and extrusion products.
MDPE (Medium Density Polyethylene)
LDPE (Low Density Polyethylene) is produced by high pressure method (147.17-196.2MPa). It has more branches and low strength. It is mostly used to produce film products.
LLDPE (Linear Low Density Polyethylene)
VLDPE (Very Low Density Polyethylene)
CPE (Chlorinated Polyethylene)