What is Polyethylene?
Polyethylene is a thermoplastic that is resistant to highly resistant chemicals and is used in a wide variety of products. In the plastics industry, the name is generally used as PE in short. The ethylene molecule C2H4 consists of two CH2 connected by double bond. (CH2=CH2) The production of polyethylene is by polymerization of ethylene. Polyethylene plastic can be low density or high density, can be molded, extruded and poured into molds of various shapes. Polyethylene is a hard, strong, durable and size stable material that absorbs water very little.
Today, polyethylene production processes are categorized into "high pressure" and "low pressure" operations. Generally low density polyethylene (LDPE) is obtained with the "high pressure" operation category, while the "low pressure" operation category produces high density (HDPE) and linear low density (LLDPE) polyethylene.
Recycled polyethylene is obtained as a result of removal of the removed plastic and the production of recycled resin. It can then be blended with untreated polyethylene, extruded and the film can be obtained and converted into bag and tubing production. Recycled polyethylene is not as clear as untreated polyethylene.
Polyethylene has a wide range of usage. Container, kitchenware, plastic box, plastic tube, pipe, toy coating, insulating layers of cables, PE, which is frequently used in packaging film production, can be preferred as much as its functionality and low cost. In addition,it finds itself a wide range of use in the construction of supermarket bags, nylon bag and sacks, plastic bottle making.
Low Density Polyethylene (LDPE)
The density of LDPE ranges from 0.910 to 0.930 g/cm3, due to the extremely long branching in the polymer chains, it is amorphous, flexible, very resistant to rupture and unaffected by chemicals. The maximum usable temperature is 80°C. The melting temperature is 120°C. It is a flexible and wrinkle-free plastic.
LDPE is one of the most demanding polymers, is economical, it is used to obtain many plastic products film bottles, luggage, frozen food packages, toys etc.
High Density Polyethylene (HDPE)
The density of HDPE ranges from 0.940 to 0.970 g/cm3, the molecular morphology is different from LDPE; the branching on long carbon chains is negligible. Thus, it is a crystalline (or semi-crystalline) polymer. Good resistance to water and chemicals. Light and outdoor conditions are not as durable as LDPE. This resistance can be increased with special fillings. Mechanical properties are very good, especially impact and tensile strength is high. With some fillers, the properties are further improved. Normally the tensile strength is around 225-350 kgf/cm2. The temperature resistance is above 100 °C.
It is suitable for many forming methods such as injection, extrusion, powder coating, film drawing, rotary molding. Keeping the injection mold temperature at 50-70 °C increases the quality of the product exiting the device. HDPE is also suitable for electrical applications.