High Density Polyethylene (HDPE)

Brief Overview

High-density polyethylene (HDPE) is a thermoplastic polymer produced from the monomer ethylene. It is the most common plastic, which accounts for over 34% of the global plastic market. As one of the most versatile plastic materials, HDPE plastic is used in various applications, including plastic bottles, milk jugs, shampoo bottles, bleach bottles, cutting boards, and piping. Known for its outstanding tensile strength and sizeable strength-to-density ratio, HDPE plastic has a high-impact resistance and melting point

Manufacturing Process

High density Polyethylene can be produced by three types of processes using Ziegler-Natta or Phillips-Type Catalyst:

1. Slurry Process:

The catalyst is diluted with any liquid hydrocarbon (e.g. hexane). A mixture of ethylene and hydrogen is passed under pressure through this slurry, after which the monomer (ethene) is polymerized to form polyethylene. The polymer-solvent slurry is evaporated to remove the solvent. Water vapour and nitrogen is then passed through the separated polymer to destroy the active sites of the catalyst, thus leaving behind HDPE.

2. Solution Process:

A mixture of ethylene and hydrogen is passed through a solution containing the Zieglar catalyst and liquid hydrocarbon under pressure. The remaining procedure is similar to the slurry process.

3. Gas Phase Process:

In a fixed bed reactor, a hydrogen and ethylene mixture is passed through a Phillips-Type catalyst. Ethylene, which is suspended in the gas, will polymerise to form HDPE. The polymer powder obtained is separated and shaped as required.

1. Plastic bottles: HDPE is great for blow-molding applications, particularly food and beverage containers, because it won’t leach into the bottles’ contents. In addition, HDPE is recyclable, which makes it an excellent choice for these highly disposable products. 
2. Toys: HDPE is UV resistant which helps keep the toys resistant to the ray’s damaging and discoloring effects. 
3. Chemical containers: With its chemical-resistant properties, HDPE is excellent for laundry, shampoo, conditioner, household cleaning products, motor oil, antifreeze, and recycling bins. The strength of HDPE bottles increases when they’ve been colored or pigmented. 
4. Pipe systems: HDPE pipe grade sheet has a higher molecular weight than the standard HDPE used in the above examples. This strengthening, with its UV resistance, makes it ideal for piping and outdoor applications.