Category (4) Low-Density Polyethylene (LDPE)

What is LDPE?

Low-Density Polyethylene, or LDPE, belongs to the branch of thermoplastic polyethylene. It is soft, lightweight, strong, and flexible. This thermoplastic material is also known for its resistance to low temperatures and corrosion, demonstrating properties that make it easy to manufacture or process. The difference between LDPE and HDPE is evident in their names, which indicates the main distinction between them. HDPE has a higher density than LDPE, while LDPE is more branched in structure, which accounts for its low density.

How is LDPE produced?

Low-Density Polyethylene is produced through a process known as free radical polymerization, which requires heat and high pressure. The first step involves collecting feedstocks from petroleum and then separating the ethylene gas from the resulting mixture. This ethylene gas is then pumped into a reactor where it undergoes polymerization with other materials. This process forms LDPE powder, which is transformed into granules. These LDPE granules can be packaged or further processed to create products through various manufacturing processes such as injection molding, blow molding, thermoforming, vacuum forming, film extrusion, and more.

History of LDPE

Low-Density Polyethylene was first produced in 1933 in England by Imperial Chemical Industries Ltd. (ICI) during studies on the effects of extremely high pressures on polyethylene polymerization. ICI obtained a patent for the process in 1937 and began commercial production in 1939. The material was first used during World War II as an insulator for radar cables.
However, Karl Ziegler of the Max Planck Institute for Coal Research in Mülheim an der Ruhr, W.Ger. (now Germany), is credited with the invention of linear HDPE, which Ziegler produced in 1953. The process was later improved by Italian chemist Giulio Natta, and the compounds are now known as Ziegler-Natta catalysts. Partly due to this innovation, Ziegler was honored with the Nobel Prize in Chemistry in 1963. Since then, using different catalysts and polymerization methods, scientists have produced polyethylene with various properties and structures. LLDPE, for example, was introduced by Phillips Petroleum Company in 1968.

FACTS:

• LDPE has a lower density compared to other PE grades.
• LDPE is a semi-crystalline polymer.
• LDPE is soft and flexible.
• LDPE is versatile.