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“The new film was designed to demonstrate dramatically the properties and suggested uses of the new product. A technician swings a baseball bat at a thin sheet of Mylar and can’t break it. An acrobat throws his weight on the film and it bounces him back into the air. A girl trapeze artist swings safely on a thin strip of Mylar. The picture was intended primarily for executive and technical personnel in manufacturing and convertising organizations to whom it is being shown by duPont sales personnel. Its impact can be assayed from convincing demonstrations that show how hot steam cannot change the film’s properties; nor does dry ice at 80 degrees below zero damage it. Similarly, acids are shown dissolving jewelry in a Mylar bag without affecting the bag itself.”
Originally a public domain film from the Library of Congress Prelinger Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).
BoPET (biaxially-oriented polyethylene terephthalate) is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties, and electrical insulation.
A variety of companies manufacture boPET and other polyester films under different brand names. In the UK and US, the most well-known trade names are Mylar, Melinex, and Hostaphan…
BoPET film was developed in the mid-1950s, originally by DuPont, Imperial Chemical Industries (ICI), and Hoechst.
In 1955 Eastman Kodak used Mylar as a support for photographic film and called it “ESTAR Base”. The very thin and tough film allowed 6,000-foot (1,800 m) reels to be exposed on long-range U-2 reconnaissance flights.
In 1964, NASA launched Echo II, a 40-metre (131 ft) diameter balloon constructed from a 9-micrometre (0.00035 in) thick mylar film sandwiched between two layers of 4.5-micrometre (0.00018 in) thick aluminum foil bonded together…
The manufacturing process begins with a film of molten polyethylene terephthalate (PET) being extruded onto a chill roll, which quenches it into the amorphous state. It is then biaxially oriented by drawing. The most common way of doing this is the sequential process, in which the film is first drawn in the machine direction using heated rollers and subsequently drawn in the transverse direction, i.e. orthogonally to the direction of travel, in a heated oven. It is also possible to draw the film in both directions simultaneously, although the equipment required for this is somewhat more elaborate. Draw ratios are typically around 3 to 4 in each direction.
Once the drawing is completed, the film is “heat set” or crystallized under tension in the oven at temperatures typically above 200 °C (392 °F). The heat setting step prevents the film from shrinking back to its original unstretched shape and locks in the molecular orientation in the film plane. The orientation of the polymer chains is responsible for the high strength and stiffness of biaxially oriented PET film, which has a typical Young’s modulus of about 4 GPa (0.58×106 psi). Another important consequence of the molecular orientation is that it induces the formation of many crystal nuclei. The crystallites that grow rapidly reach the boundary of the neighboring crystallite and remain smaller than the wavelength of visible light. As a result, biaxially oriented PET film has excellent clarity, despite its semicrystalline structure.
If it were produced without any additives, the surface of the film would be so smooth that layers would adhere strongly to one another when the film is wound up, similar to the sticking of clean glass plates when stacked. To make handling possible, microscopic inert inorganic particles are usually embedded in the PET to roughen the surface of the film such as silicon dioxide…