How Mylar Is Made
Molten polyethylene terephthalate (PET) is extruded as a thin film onto a chilled surface, such as a roller.
The film is drawn biaxially. Special machinery may be used to draw the film in both directions at once. More commonly, the film is drawn first in one direction and then in the transverse (orthogonal) direction. Heated rollers are effective for achieving this.
Finally, the film is heat set by holding it under tension above 200 °C (392 °F)<<<<<<<<<<<<<<<<<<<
A pure film is so smooth it sticks to itself when rolled, so inorganic particles may be embedded in the surface. Vapor deposition may be used to evaporate gold, aluminum or another metal onto the plastic.
