Polyolefin is the largest class of organic thermoplastic polymers. They are non-polar, odorless, nonporous materials that are often used in consumer goods, structural plastics, food packaging and industrial products. As a result, they are also called "commodity thermoplastics." The name means "oil-like," and refers to the oily or waxy texture of this class of plastic resins. This class of polymers is more commonly referred to as polyalkene, although "polyolefin" is still a common term in organic chemistry and the petrochemical industry.
In some places, the term is also used to refer to plastic shrink wrap, a thermoplastic material that expands when heated to lower temperatures relative to other thermoplastics. The material retains its odorless, nonporous properties as it heats and cools, making it an ideal material in food packaging. Polyolefin is also used in packaging of higher-end consumer goods like CDs or electronics as it keeps the goods safe from moisture, dust, and static.
At the molecular level, these substances are created by the polymerization of a simple olefin. Simple olefins, also known as alkenes, are organic hydrocarbons comprised of one double-bonded pair of carbon atoms and four hydrogen atoms. The other types of more complex olefins include ethylene, propylene, the butenes, and butadiene. All natural ones are derived from oil and natural gas.
Polyolefin materials are made up of only carbon and hydrogen atoms. The double-bond carbon atoms form the core of the molecule. Materials such as poly-alpha-olefin, polybutene, polyethylene and polypropylene have more complex olefin branches that are bonded to the double-bonded carbon molecules.
Easy and inexpensive to dye and mold, polyolefins are preferred plastic resins in industry and for consumer goods. Higher ones — those polymers created from more complex olefins — maintain their molecular structure at hotter and colder temperatures than lower ones. In general, they melt at extremely high temperatures and shatter at extremely cold temperatures.
Polyolefin materials include polybutene, polyethylene, and polypropylene. Polybutene is a liquid polymer used in lubricants, sealants, synthetic rubber, makeup, and lipstick. Polyethylene is commonly used in products like shrink wrap and plastic grocery bags. Polypropylene is a hard plastic resin used in products from food packaging, electronics, carpeting and dishwasher-safe plastic food containers.