In the 1950s, a trio of chemical companies, Hoechst, DuPont, and Imperial Chemical, developed Mylar–a stretched polyester film that is commonly used for solar filters, protective plastic coatings, insulators, space blankets, and shiny helium balloons. The technical composition of the groundbreaking material is biaxially oriented polyethylene terephthalate, or BoPET. NASA was one of the first to use and experience the benefits in its 1964 Echo II balloon.
To create Mylar, molten PET is extruded as a thin film over a chilled roller or other surface. Special machinery draws the film in biaxial directions using heated rollers. The final step involves setting the film by holding it under pressure at a high temperature. The result is an extremely smooth and pure film that adheres to itself. To prevent this, inorganic particles or metals can be embedded in the surface.
The properties of Mylar make it an excellent component for food packaging applications such as yogurt lids, roasting bags, and various foil packages. Because of its electrical insulating properties, it is often used in manufacturing, automotive, electronics, and space travel applications.
A very popular use for Mylar within plastic fasteners is Mylar washers. Mylar washers have a number of uses, including: