PET film (Polyethylene terephthalate) or more commonly known as Polyester is an umbrella term for any polymer material that is cast into a wide thin film like material. There are different types of polyester film used. In general, Polyester film is a versatile plastic that is widely used for many applications. It is a tough and durable plastic that is able to withstand many temperatures. They are available in large ranges of thickness and though it is thin, it has exceptional strength as it does not tear or stretch. It also has excellent thermal stability and is able to withstand most common chemicals and media and is able to absorb fluids. They are used for various applications that need tough, strong, durable and chemical resistant plastic sheets. It is used for archival storage of documents and can provide a shiny and protective coating. However, you can find Polyester film being used in a wide array of applications such as lamination, carrier films, face shields, the manufacture of insulating shims, gaskets and seals but mostly for any applications that require electrical insulation.
Mylar is a generic term used to refer to plastic sheets and polyester film though it is actually the registered trademark and brand name for a special type of stretched polyester film. It is also known as BoPET (Biaxially-oriented polyethylene terephthalate) and it is made from stretched PET films. Therefore, it comes under a type of Polyester film that is widely used today. It has incredibly high quality as it’s known and used for its high tensile strength, odor barrier, transparency, durability, chemical and dimensional stability but mainly for its electrical insulation. Mylar has been used in a broad range of fields, having several applications in electronics, imaging and graphics, industrial and also the packaging market. Mylar is most commonly used as an electrical and thermal insulator, reflective material, and decoration such as kites and musical instruments. In addition, it can be formed to make trays for frozen dinners and for flexible packaging trays and lids for the food industry due to the film being less absorbent to gasses than other plastics. However, when used as a laminate, it provides an excellent barrier against moisture and gas.