Talk:PET film (biaxially oriented)
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can anyone talk about heat shrink properties?
Because biaxially oriented PET film is stretched, the PET molecules are under tension. Therefore they will try to shrink back to their original form when heated. This is mostly prevented by the crystallinity of the film from the "heat setting" step in manufacturing, but some residual tendency to shrink does remain. Levels of a couple percent of shrinkage can occur at high temperatures. How much the film will shrink at which temperature depends greatly on the grade of film chosen and what properties the grade is optimized for. (Magnetic tape base will be different than food packaging material, for instance.) Cynthia Bennett 20:54, 7 November 2005 (UTC)
- Is mylar used for heat shrinking storm windows? or is that something else? njh 08:05, 16 February 2006 (UTC)
- No, polyolefin is the polymer most commonly used for shrink wrapping -- Dogears 01:28, 17 February 2006 (UTC)
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[edit] "mylar" balloons
So if these aren't even mylar, why is there a pic of one on the page? i say remove it. SECProto 00:28, 16 January 2006 (UTC)
- Yea I agree, removing it. 220.239.130.145 02:17, 31 January 2006 (UTC)
So okay, a foil that looks like the baloon foil, the one people use to deflect heat of their window or car, is mylar, and also the white cover sheets for maps and architectural drawings is mylar? We call it mylar. Maybe I'll try and take a picture of those two things. Maybe you will. 66.41.66.213 06:23, 1 May 2006 (UTC)
[edit] insulation
- Insulation for houses and tents in cold environments, covering the inner walls with the metallized surface facing inward, thus reflecting heat back into the space
- Insulation for houses and tents in hot environments, covering the outer walls with the metallized surface facing outward, thus reflecting heat away from the space
I was under the impression that reflective film insulation relies more on low emissitivity than on reflecting incoming photons. Does anyone know the truth? njh 08:03, 16 February 2006 (UTC)
[edit] (biaxially oriented)
Why does the title have this part in it when there is no PET film? It should probably be moved again. --Rory096 19:00, 12 March 2006 (UTC)
- That's because there is also non-oriented PET film or sheet, also called APET or CPET. Nobody has written about that (yet). I guess I've just volunteered for the job, but it's too late to start today. I just got finished fixing all the internal links for boPET film and cleaning up the text of the article itself. The brand names "Mylar", "Melinex", "Hostaphan", "Estar", "Diafoil", "Lumirror" etc., etc., etc. all refer to biaxially oriented PET film.Cynthia Bennett 23:40, 12 March 2006 (UTC)
[edit] Need more technical information on oriented PET films
The article needs more technical information. For example, what is the percentage of crystalization in biaxially oriented film? The Polyethylene terephthalate article says the upper limit for PET is 60%, is it true for oriented PET films? Also, is the Tg of oriented PET higher than un-oriented films? Those are the things I'd like to know. Wilsonbond 15:15, 8 November 2006 (UTC)
To answer those questions: 1. The acheivable crystallinity of boPET films tops out at about 50%. 2. Because the chains in the amorphous regions are under strain, the Tg should be higher. In commericial PET films you can't see a Tg "step" in the DSC scan though. With less oriented, non-heat set samples, you can see that the Tg step getting broader and smaller as the amount of draw increases. (#1 is pretty straightforward, based on the density of the amorphous and crystalline phases and the density of commercial boPET film. I'm not aware of any citations on #2, it's my own experience. On the other hand, its not very surprising.) CindyB 09:59, 12 November 2006 (UTC)
[edit] Climate Change
America is researching whether flying sheets of mylar into our atmosphere will reflect the sun's ray and stop global warming. Should this be placed on this page?
