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 1964, NASA launched Echo II (the second mission of Project Echo). It was a 40 m (131 ft) diameter balloon constructed from "a 0.35mil (9µm) thick mylar film sandwiched between two layers of 0.18 mil (4.5µm) thick aluminum foil and 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.
I woke up one morning heard a robin's song.
I asked that robin "Why do you sing?"
"It was a voice whose rhymes are worlds
That made my song for me
How could I not sing?"
I woke up on morning heard a robins song
I asked that robin "Who made your throat?"
"That same hand that flies a million dawns
Made my tiny throat and wrote my songs
How could I not sing?"
I built an arbor and I asked the vine
"How come you grow so tall?"
"If I can make it above the wall
That same hand that holds out hope for all
Will gild me in the morning sky
And though I cannot sing
That hand a gentle wind will bring
And make a rustling lullaby
For milky sleeping babes
How could I not grow?"
I woke up one morning and I asked the sky
"How can you bear such emptiness?"
"For that bright eye that looks out and smiles
And makes my night her day
What would I not bear?"
I woke up one morning and I heard her voice
She called me by my name
What would I not give
To be called her child
What would I not give
To be called her friend
I'm gonna wake up one morning I'm gonna see her face
Smiling down on me
That robin's song and that morning sky
Are all the hope I need
I don't know how and I don't know why
But I'm gonna wake up one morning and I'll see her face
Smiling Down on me
I'm gonna wake up one morning
I'm gonna wake up one morning