Polyethylene: The Basics

Posted by Hedwin on November 10, 2016

PE 1.jpg

A truly versatile polymer, polyethylene (PE) has an interesting history and an excellent track record in many applications. It is relatively easy to mass produce, easily modifiable, and widely recyclable. In fact, polyethylene is one of the most commonly used resins in the world.

Polyethylene is a petroleum-based product, a polymer, which consists of chains of individual molecules, or monomers. PE is comprised of long, repeating chains of ethylene molecules, each consisting of four hydrogen and two carbon atoms. During the polymerization process, a catalyst joins the ethylene monomers together to form polyethylene.

Polyethylene was originally discovered in 1898. In 1933, a failed lab experiment at Imperial Chemicals Industries (ICI) in London produced the same substance quite by accident, and by 1936, ICI had realized the potential value of this new polymer. After several trial-and-error attempts, the lab was able to successfully reproduce it. As ICI began to develop its large-scale production capabilities, World War II provided an ideal testing ground for the new material; the British military secretly put the highly classified new product to the test as insulation for their radar cables. The results were stellar, and by 1944, polyethylene was licensed in the United States. It has since become one of the most widely used substances on the planet. 

By altering catalyst and reactor conditions, the properties of polyethylene can be manipulated in many ways to create several varieties of the polymer, allowing it be used in a wide range of applications.

The most common types of polyethylene are High Density PE (HDPE) and Low Density PE (LDPE). Their properties vary widely, as do their ideal applications.

HDPE

LDPE

Rigid

Semi-rigid

Waxy

Translucent

Extremely tough at low temperatures

Very tough

Very good moisture barrier

Good moisture barrier

Very good chemical resistance

Good chemical resistance

Applications:

  • Milk Jugs
  • Detergent bottles
  • Garbage bins
  • Drums and pails
  • Prosthetics
  • Water pipes

Applications:

  • Films
  • Wraps
  • Food containers
  • Disposable gloves
  • Garbage bags
  • Electrical cables

Linear Low Density PE (LLDPE), another common type of PE, combines the density of LDPE with the superior properties of HDPE.

The versatility of PE resins allows them to be processed in several ways. All processing methods begin with extrusion, which involves melting a pellet form into a pliable, moldable state. Depending on end product requirements, the melted resin can then be formed into sheets, or blow molded, injection molded, or thermoformed. Various combinations of these processes can also be employed.

PE 2.jpgIn 1946, just two years after polyethylene was first made commercially available in the United States, Lenox Burkhed and Tom Winstead were experimenting with using new PE resins for packaging applications. Together they formed a company called the Hedwin Corporation and went on to patent the packages — the predecessors of Hedwin’s CUBITAINER®, HEDLINER®, PAYLINER®, WINLINER® and TOPLINER® products, specifically designed to harness the inherent power of different types of resins.

CUBITAINER® is made from either pure LDPE or a proprietary blend of LDPE and LLDPE. HEDLINER® and WINLINER® are made from the pliable LDPE. The rigid TOPLINER® products are formed using HDPE. And to bring true diversity to our PAYLINER® product line, we also offer these pail liner products in both LDPE and HDPE.

For more information about the applications that commonly use PE resins, visit the Applications section of our site!

Explore Applications

Topics: Product Information