Polyethylene (PE) or polythene is a thermoplastics material, heavily used in consumer products (notably for plastics shopping bags and packaging bottles). It is best known for its excellent chemical resistance properties. Due to its relatively low price and common application, it is classified as a commodity plastics. Over 60 million tons of this material are produced worldwide every year. Below are 3 common types of polyethylene.
Types of Polyethylene
The 3 major branch of PE are: High Density Polyethylene (HDPE); Linear Low Density Polyethylene (LLDPE); and Low Density Polyethylene (LDPE)
HDPE is a relatively dense material with density over 0.941 g/cm3. Among the 3, HDPE is the stiffest and are mostly used for production of toys. The average melt temperature is about 180°C .
LLDPE has a density range of 0.915–0.925 g/cm3. In term of flexibility, it is somewhere between HDPE and LDPE. The average melt temperature is at 130°C.
LDPE is the most flexible and softest among the 3 types of PE. Its density ranges from 0.910–0.940 g/cm3 and the melt temperature is lower 120°C. Due to its flexibility, it is open used to produce squeeze bottles and food storage container lids.
Material Properties
- Stiffness increase from LDPE to LLDPE to HDPE
- Strength increases from LDPE to LLDPE to HDPE
- Resistant to water and solvents
- Low melting temperature
- Inexpensive
- Excellent electrical resistance
Applications
- Trash bags (LDPE and LLDPE)
- Packaging bottles (HDPE) – shampoo bottles, lubricant bottles, etc.
- Toys (HDPE)
- Trash bins (HDPE)
- Pipe for natural gas (HDPE)
- Packaging films and containers
- Electrical wiring coatings
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