← Back to Articles

What are Polyolefins?

Polyolefins are high molecular weight hydrocarbons. They include Low-Density and High Density Polyethylene and Polypropylene. All are break-resistant, nontoxic, and non-contaminating. These are the only plastics lighter that water. They easily withstand exposure to nearly all chemicals at room temperature for up to 24 hours. Strong oxidizing agents eventually cause embitterment. All polyolefins can be damaged by long exposure to ultraviolet light.  

Polyethylene- the polymerization of ethylene results in an essentially straight chain, high molecular weight hydrocarbon. Polyethylenes are classified according to the relative degree of branching (side chain formation) in their molecular structures, which can be controlled with selective catalysts.

Like other polyolefins, the polyethlyenes are chemically inert. Strong oxidizing agents will eventually cause oxidation and embitterment. They have no known solvent at room temperature. Aggressive solvents will cause softening or swelling, but these effects are normally reversible.

Low Density Polyethylene - (LDPE) has more extensive branching, resulting in a less compact molecular structure.

High Density Polyethylene – (HDPE) has minimal branching, which makes it more rigid and less permeable.

Polypropylene – (PP) is similar to polyethylene, but each unit of the chain has a methyl pendant group attached. It is translucent, autoclavable, and has no known solvent at room temperature. It is slightly more susceptible than polyethylene to strong oxidizing agents. It offers the best stress-crack resistance of the polyolefins. Products made of polypropylene are brittle at ambient temperatures and may crack or break if dropped from bench top height.

Polypropylene Copolymer – (PPCO) is an essentially linear copolymer with repeated sequences of ethylene and propylene. It combines some of the advantages of both polymers. PPCO is autoclavable, and offers much of the high temperature performance of polypropylene. It also provides some of the low-temperature strength and flexibility of polyethylene.

Title: What are Polyolefins?
Description: Polyolefins include LDPE, HDPE, and PP.
Published: 6/13/2008
Last Edited: 9/19/2013
17 users found this article useful. Was this article useful to you?

Information disclaimer:

The information contained in this article is for general information purposes only. The information is provided by United States Plastic Corp. and while we endeavor to keep the information up to date and correct, we make no representations or warranties of any kind, express or implied, about the completeness, accuracy, reliability, suitability or availability with respect to the website or the information, products, services, or related graphics contained on the website for any purpose. Any reliance you place on such information is therefore strictly at your own risk.

In no event will we be liable for any loss or damage including without limitation, indirect or consequential loss or damage, or any loss or damage whatsoever arising from loss of materials, time or profits arising out of, or in connection with, the use of this information.