What is High-Density Polyethylene (HDPE)?

High-density polyethene (HDPE) is a thermoplastic polymer produced from the monomer ethylene.

HDPE is a cost-effective polymer with linear structure (low degree of branching).

HDPE is now among the most common and popular PE materials in the market. HDPE has excellent strength and density properties, which allows the industries to use it in the production of a wide range of materials.

HDPE Production Method

The HDPE production process consists of:

- Ethylene production: Ethylene is manufactured at low temperature and pressure, derived from either modifying natural gas (a methane, ethane, propane mix) or catalytic cracking of crude oil into gasoline.
- Polymerization: Ethylene monomers are polymerized in solvent together with catalyst, hydrogen and comonomer. The polymerization heat is cooled through external circulation heat exchanger. The reacted slurry is transferred to the separation/drying process.
- Separation/Drying: Slurry is transferred to a high-speed centrifuge from which it is separated into solvent and wet powders. The separated solvent is supplied to the reactor and some solvents are recycled in the process through refining. Wet powders are transferred to the powder dryer and dried.

 

HDPE Applications

HDPE is used to make a variety of products such as:

- Piping, bottles and buckets

- Water pipe flanges (HDPE pipe grade)

- HDPE filament for 3D printers

- Strong packaging materials: bottle caps, plastic milk bottles, drums, and bulk containers for industrial use

- Fibers for ropes, nets, and industrial fabrics

- Vehicle fuel tanks

- Boat parts

- HDPE plastic chairs and tables

- Playground slides and swing seats

- Consumer products like trash cans, recycling bins, ice cube containers, and toys

- Chemical tanks and IBC storage tanks

- Cutting boards for food preparation

- Marine construction (pile guards, bumpers, anti-skid surfaces)

- Orthotics and prosthetics – AFOs, KAFOs

HDPE Main Properties

- Fair toughness and stiffness

- Environmental stress crack resistance

- Easy to process

- Easy to weld

- Low moisture absorption

- Excellent surface for food preparation

- Good chemical and corrosion resistance

- Easy to fabricate and machine

- Low weight

HDPE Advantages

- Excellent resistance to chemicals, solvents and hydrolysis

- High crystallinity (more than 90%)

- Environmental Stress Crack Resistance (ESCR) 

- Impact resistance

- Easy processability

- Cost-effectiveness

HDPE Disadvantages

- Difficult to bond

- Poor weathering

- Highly Flammable

- Not biodegradable

- Non-resistant to oxidizing acids

- Non-resistant to chlorinated hydrocarbons

- High thermal Expansion

- Non-resistant to high temperatures 

However, some grades have been smartly upgraded in order to offer improved performances.