Difference Between Polyolefin and Polyethylene

Key Difference – Polyolefin vs Polyethylene
 

Both Polyolefin and Polyethylene are thermoplastic polymer materials. The key difference between polyolefin and polyethylene is that polyolefin is made from the polymerization of small alkenes whereas polyethylene is made from the polymerization of ethylene molecules. Polyethylene is a form of polyolefin. That is because polyethylene is made from ethylene monomers; ethylene is a small olefin compound.

CONTENTS

1. Overview and Key Difference
2. What is Polyolefin
3. What is Polyethylene
4. Similarities Between Polyolefin and Polyethylene
5. Side by Side Comparison – Polyolefin vs Polyethylene in Tabular Form
6. Summary

What is Polyolefin?

Polyolefin is a polymer material made from the polymerization of small alkene compounds. Alkenes are organic compounds containing one or more double bonds between carbon atoms. The molecular formula of an alkene is given as C_nH_2n whereas n is a small, whole number. When these alkenes form polymers, they are known as monomers.

Figure 01: Polypropylene is a good example for Polyolefin

Examples of polyolefin compounds include polyethylene (formed from the olefin ethylene), polypropylene (formed from the olefin propylene), polymethylpentane, etc. In the industrial scale productions, these polymers are made in the presence of a catalyst such as Ziegler-Natta catalyst.

What is Polyethylene?

Polyethylene is a common thermoplastic polymer material formed from ethylene monomers. It is denoted by PE. The repeating unit of PE is (C₂H₄)_n with variable “n” values. The most important application of polyethylene is as a packaging material.

Figure 02: Repeating Unit of PE

Polyethylene Grading

There are several grades of polyethylene categorized based on the density and other properties of the polymer material.

• UHMW (ultra-high molecular weight PE)
• ULMW (ultra-low molecular weight PE)
• HDPE (high density polyethylene)
• PEX (cross-linked polyethylene)
• LDPE (low density polyethylene)

Properties of Polyethylene

There are many important properties of polyethylene; mechanical properties, thermal properties, chemical properties, optical properties and electrical properties.

• Mechanical properties – low strength, low hardness and rigidity, high ductility, high impact strength, low fiction
• Thermal properties – the melting point is 80° But the melting varies with the form of polyethylene
• Chemical properties – PE is nonpolar. It is a saturated hydrocarbon compound. Excellent chemical resistance, no water absorption, low gas permeability, brittle when exposed to direct sunlight
• Optical properties – most of the times, transparent. Can be milky-opaque or opaque.
• Electrical properties – good electrical insulation, tracking resistance.

Applications of polyethylene include mainly as a packaging material. Apart from that, HDPE is used for blow moulding, injection moulding, film production, pipe production, etc. LDPE is used mainly for the production of thin films, extrusion coatings, injection moulding, wire and cable productions, etc.

What are the Similarities Between Polyolefin and Polyethylene?

• Both Polyolefin and Polyethylene are made from alkene monomers.
• Both are thermoplastic polymer materials.
• Both are hydrocarbons.

What is the Difference Between Polyolefin and Polyethylene?

Summary – Polyolefin vs Polyethylene

Polyolefin are polymer materials made from small alkene monomers. Polyethylene is a good example for polyolefin. The difference between polyolefin and polyethylene is that polyolefin is made from the polymerization of alkenes whereas polyethylene is made from the polymerization of ethylene molecules.

Reference:

1. Britannica, The Editors of Encyclopaedia. “Polyolefin.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 26 July 2012. Available here 
2. “Polyethylene.” Wikipedia, Wikimedia Foundation, 28 Mar. 2018. Available here 
3. Rogers, Tony. “Creative Mechanisms Blog .” Everything You Need To Know About Polyethylene (PE). Available here 

Image Courtesy:

1.’Polypropylene isotactic mini trp’By PakpongICCH444 – Own work, (CC BY-SA 4.0) via Commons Wikimedia  
2.’Polyethylene repeat unit’By Magmar452 – Own work, (Public Domain) via Commons Wikimedia  

Related posts:

Difference Between Polymer and Plastic Difference Between Polymer and Biopolymer Difference Between Polyethylene and Polypropylene Difference Between Resin and Plastic Difference Between HDPE and PP