High density Polyethylene (HDPE)

High density polyethylene is a thermo-plastic polymer. Its monomer unit is ethylene. Ethylene, also known as ethene, is a C2H4 hydrocarbon. PEHD (polyethylene high density), polythene alkathene, are all names for high density polyethylene.

If a plastic material has a Resin Identification Code (RIC) - 2 written on it, that plastic material is made of HDPE. RIC -2 is an abbreviation for HDPE. Karl Ziegler discovered high density polyethylene in 1953. In 1963, Karl Ziegler was awarded the Nobel Prize in Chemistry. Soon after, HDPE was recognized as an important raw material in the production of a broad range of materials.

During World War II, it was used as a valuable material for insulation, underwater coating for cables, and for critical military operations. As a result, HDPE became an extremely valuable resource during World War II. Because of its numerous applications, HDPE remains one of the most broadly produced polymers. It accounts for more than 34% of the global market of plastic.

Production Process

High - Density Polyethylene (HDPE) is produced through ethylene’s gas phase polymerization. Petroleum performs a process of 'cracking' under controlled conditions. As a result, ethylene gas is produced. These ethylene molecules are now polymerized to form HDPE. Afterwards, the HDPE undergoes the process of separation and drying. It can also be produced through catalytic processes like Cr – Si catalysis or Ziegler – Natta catalysis.

Characteristics of High-Density Polyethylene (HDPE)

Because of its unique properties, HDPE has a wide range of uses. To understand its various applications in the industry, you must first understand its properties. As a result, various HDPE properties are listed below –

It is malleable and can be shaped repeatedly. As a result, it is a thermoplastic polymer.
It's known for having a high strength to density ratio.
Its structure has little branching.
It outperforms low density polyethylene in terms of tensile strength and intermolecular forces.
It is a lightweight and strong polymer made of plastic.
It has a melting point of 130.8°C.
It has a density of 940 kg/m3.
It can withstand lower temperatures than LDPE.
Its crystallization temperature is 111.9°C.
It is more opaque and brittle than low density polyethylene.
It is electrically and chemically resistant.
It is resistant to a wide range of solvents.
Its specific heat capacity ranges from 1330 to 2400 J/kg – K.
It has a fusion latent heat of fusion of 178.6 kJ/kg.

Applications of HDPE (High-Density Polyethylene)

All of the above-mentioned advantageous properties of high – density polyethylene make it suitable for a wide range of applications. A few HDPE applications are listed below –

It is used to make disposable suits for a variety of applications.
HDPE is used to make bottle crates.
It is used to protect buildings as house wrap.
It is used to make ice cube trays, chairs, stools, bottles, and other items.
It can be used to make pipes that can be used for both sewage water and potable water.
Its fibres are capable of being spun into a rope.
Cutting boards are made of high density polyethylene.
High density polyethylene is used to make food and beverage containers.
HDPE is used to make a variety of playground equipment and toys.
Because it is a long-lasting and strong material, it is also used in construction.
It is used to make milk bottles and jam cans because it is resistant to corrosion.
It is used in cosmetic surgery, particularly rhinoplasty and facial surgery.
It's found in doormats.
Food packaging makes use of high density polyethylene film.
HDPE is a polymer that is used in wood plastic composites.
HDPE is used to make plastic envelopes, which are commonly used in mailing.
It is used in three-dimensional printing filaments.

Difference between High Density Polyethylene (HDPE) and Low Density Polyethylene (LDPE)

High Density Polyethylene (HDPE)	Low Density Polyethylene (LDPE)
It is slightly denser than low – density polyethylene.	It is slightly less dense than high density polyethylene.
It exhibits high strength to density ratio	It exhibits low strength to density ratio
It resists lower temperatures efficiently	It cannot resist lower temperatures efficiently
It shows less branching	It shows more branching
It has greater intermolecular forces as well as tensile strength.	It has lower tensile strength and intermolecular forces.
It is opaquer and harder	It is transparent and softer
It shows less flexibility	It shoes more flexibility
It has low resilient qualities	It has more resilient qualities