Mylar

Mylar. It is a brand name for a biaxially-oriented polyethylene terephthalate (BoPET) film, a type of polyester resin renowned for its high tensile strength and dimensional stability. Developed by DuPont in the mid-20th century, it has become a genericized trademark for similar films produced globally. Its unique combination of properties has led to its adoption in a vast array of industrial, consumer, and scientific applications.

Introduction

The material is a transparent, thermoplastic polymer film produced through a specialized stretching process. This orientation imparts exceptional mechanical and physical characteristics not found in unoriented polyethylene terephthalate. While often used interchangeably with the term "BoPET," it specifically refers to the product line originally created by the DuPont company. Its development was a significant advancement in polymer chemistry, providing a durable, flexible alternative to more traditional materials like cellophane and certain metal foils.

Properties

The film exhibits high tensile strength, chemical resistance, and excellent electrical insulation properties, making it suitable for demanding environments. It has a very low gas permeability, which is critical for packaging applications requiring a high barrier. Its surface can be coated with metals like aluminum to create a highly reflective and impermeable material, as seen in emergency blankets and balloons. The material also demonstrates good dimensional stability across a wide temperature range and has high optical clarity, which is utilized in applications from overhead projector transparencies to window film.

Applications

Its applications are extraordinarily diverse, spanning numerous fields. In packaging, it is used for food packaging, particularly for snacks and coffee bags, and as a lid for yogurt containers. In electronics, it serves as a dielectric film in capacitors and as insulation for magnetic tape and wires. The NASA space program has employed it extensively in satellite insulation and space suit components. Other notable uses include as a substrate for printed circuit boards, in loudspeaker diaphragms, for decorative metallization, and in the construction of solar sail prototypes.

History

The history of the material begins with the foundational work on polyethylene terephthalate by John Rex Whinfield and James Tennant Dickson of the Calico Printers' Association in the 1940s. DuPont subsequently licensed the technology and, through research at its DuPont Experimental Station, developed a commercially viable process for producing a biaxially oriented film. It was introduced to the market in 1952, with early uses including recording tape and decorative metallized yarns called "Lurex." Its role expanded dramatically during the Space Race, where its properties were critical for the success of missions like Echo 1, a passive communications satellite.

Manufacturing

The manufacturing process involves first polymerizing ethylene glycol and dimethyl terephthalate or terephthalic acid to create polyethylene terephthalate resin. This resin is then extruded into a sheet, which is subsequently stretched in both the machine direction and transverse direction in a sequential or simultaneous drawing process. This biaxial orientation aligns the polymer chains, greatly enhancing the film's strength and stability. The film can then undergo various finishing processes, such as coating with polyvinylidene chloride for improved barrier properties or vacuum metallization with aluminum. Category:Polyesters Category:DuPont brands Category:Plastics