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Heat shrink properties[edit]

can anyone talk about heat shrink properties?

also the stuff is probably bad for the environment where's the mention of that?

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)

"Mylar" balloons[edit]

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)

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. 06:23, 1 May 2006 (UTC)


  1. 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
  2. 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)

(biaxially oriented)[edit]

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)

Need more technical information on oriented PET films[edit]

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)

Climate Change[edit]

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?

Floppy Disks?[edit] says that Mylar is the material used for the 'disk' in a floppy disk.

That's a pretty important application that should be mentioned, no?

I know nothing about the topic, just trying to find for myself if there is any metal on such a disk, so that I can see if it is safe to put said disk and the plasic casing (without aluminum pieces, which I have removed) in my betta splendens' fish tank. Metals are supposedly deadly to them, but I can't seem to find the information.

Let me know if you know anything, hope I helped.Lackinglatin 09:22, 12 April 2007 (UTC)

mylar flammability[edit]

A Google search brings up contribution of mylar insulators to tragic aircraft fires, which resulted in new regulations in 2005. We could use a knowledgeable article about this. I have ordered 3ml mylar film for use by my HS sophomore chem students in science fair projects. They will be investigating applications to thermal insulation of dwellings, among other things. Such applications heighten the need for information on flammability. Can I even cover a display bulletin board in a classroom? What are flammability regulations on interior and exterior use of pet films? Mporter chemtchr 03:33, 30 August 2007 (UTC)

PET film will burn if exposed to flame, but it is less flammable than other common types of plastic film like PE or PP. Thicker layers will tend to self-extinguish, but thinner film has more surface area and is more likely to sustain a fire. 3 mils is fairly thick and will likely go out if you ignite it. The combination of thin PET and metallized aluminum burns more easily than the PET film itself, since the oxidation of aluminum is fairly exothermic. The role the metallized insulators are believed to have played in the Lockerbie incident were helping the fire that already existed spread. Metallized PET film does not burst into flames all by it's lonesome. Don't worry about your sophomores unless they are incorrigible with matches. But then they'd be setting their clothes on fire constantly too. —Preceding unsigned comment added by (talk) 18:01, 2 September 2007 (UTC)

Who has edited this entry?[edit]

Mporter chemtchr 18:48, 5 September 2007 (UTC)There should be a link here to the Wikipedia entry on the air disaster of Swissair Flight 111 (SR-111, SWR-111). That article contains this text:

In September 1999 Swissair and Boeing offered the families of the passengers full compensatory damages. This was rejected in favor of a $19.8 billion suit against Swissair and DuPont, the supplier of Mylar insulation sheathing. The claim was rejected in a US federal court in February 2002.[22]

I am finding it surprisingly difficult to find information on fire safety for metallized boPET film. I appreciate the ananymous response to my question, but it is exactly the aceleration of an existing fire (into a deathtrap) that concerns us when we think of use of materials in dwellings (let alone the third floor of an aging public schoolMporter chemtchr 18:48, 5 September 2007 (UTC)).

In Wikipedia anyone can write anything, including you Mporter. Happy paniking about nonsense. Consider all those PET fibers out there. We're probably all in a fireball right now. Wood also will sustain and spread a fire. I suggest you remove all wooden objects from your classroom. Signed-- intentionally anonymous, like the rest of Wikipeidians. —Preceding unsigned comment added by (talk) 21:19, 7 September 2007 (UTC)

Information on the Swissair flight is actually pretty easy to find. Have a look at this link at the FAA: FAA's lessons learned. Metallized boPET's contribution to the accident came from the mistaken idea that metallized boPET would self-extinguish when ignited and thus no other measures needed to be taken to prevent electrical fires from spreading. The mistaken idea came from the fact that it did self-extinguish in the vertical burning test that was required at the time. As a result of the accident and the ensuing evaluation, we have learned how important it is to not rely solely on laboratory-like flammability tests on individual components of an assembly if we want to be sure that the assembly will not burn when exposed to fire. Instead the entire assembly needs to be tested, because fires are affected by material shapes and combinations. Metallized boPET film is NOT MORE FLAMMABLE than many materials we use, but it does burn when put into certain configurations. The problem was that the people who built the aircraft thought that it would not burn at all. Even when people try to do their best, sometimes things go wrong because we don't understand everything (yet). When things go wrong, we should try to learn from it and prevent repititions, not just sic lawyers on anyone around with "deep pockets". -- Intentionally anonymous, like most Wikipedians —Preceding unsigned comment added by (talk) 14:32, 8 September 2007 (UTC)

Indeed, finding new applications (and learning from things that have gone wrong) is exactly my aim, in inviting my students to do science fair projects with this interesting material. Classroom decor isn't a frivolous concern (indeed the fire department does restrict paper displays to less than 40% of classroom wall space), but it isn't my main interest. A surprising number of my best students have gone on to major in chemical engineering - I'm looking for earlier exposure to materials science (my own background is biochem). Metallized bopet film is cool stuff, likely to grip their imaginations. Your link to the fire safety test is helpful - maybe some students would be able to work with our fire dept to design their own test. I would expect all you engineers to be lining up to do that, especially if you are experienced in that area and the aircraft fire caught you by surprise. On the net, I find several business sites that say world bopet production presently exceeds demand, due to the huge expansion of production in China. A Thai manufacturer (of titanium film, which is what I got my kids) suggests heat insulation for windows, walls, roofs and air ducts. That might be a good idea in energy terms, in view of the looming possibility of climate change. I had expected to find vigorous scientific discussions of flammability concerns for these new structural applications, and was truly amazed that the discussion of the (apparently several) air disasters was all that finally came up. Is it true the airlines have delayed implementation of the new regulation requiring removal of the film from the existing fleet, maybe till 2010 or never, because of the expense involved? Imagine waiting to worry about the configuration in structures until after the film is installed in buildings around the world, or even shrink-wrapped around the ventilation systems. Mporter chemtchr 05:13, 18 September 2007 (UTC)

Added metallised films article[edit]

I have started a metallised films article as every mention of aluminised or metallised films directed here. Any suggestions on improvements please. —Preceding unsigned comment added by BeamerNZ (talkcontribs) 11:57, 15 December 2007 (UTC)


PET Is not Polyester (but is related) PET is not Mylar Mylar is a brand name for Polyester —Preceding unsigned comment added by (talk) 12:18, 27 February 2008 (UTC) Yes, PET is a polyester, and is the polyester thermoplastic resin being referred to. Mylar is a trademark which was applied to other products besides those consisting mostly of PET. (talk) 08:22, 23 March 2013 (UTC)

Cosmoline replacement[edit]

"Cosmoline's most common use is in the storage and preservation of firearms. Previously, cosmoline was used to preserve other items. Objects the size of entire vehicles could be preserved for future use with cosmoline. Due to its gelatinous nature, cosmoline can be difficult to remove completely from firearms and, as such, is being extensively replaced with vacuum-pack PET film."

Can anyone add to the article about this? I am interested in using PET film on firearms and knives. -- (talk) 02:16, 15 April 2010 (UTC)

This paragraph is focused on Cosmoline rather than PET and thus would hardly fit. Materialscientist (talk) 03:01, 15 April 2010 (UTC)

No, silly billy nilly, I was unclear, sorry. I meant could someone tell ME more about the use of PET film. -- (talk) 04:57, 15 April 2010 (UTC)

Ah .. maybe Firearms project knows something. Materialscientist (talk) 05:01, 15 April 2010 (UTC)

Material properties needed[edit]

It is unclear if BoPET has the same properties as ordinary PET. The Polyethylene terephthalate (PET) article has a brief list of properties, whereas the Polyester article doesn't have any. It would be nice to clarify this for the reader. For an example of an extensive list of properties, see the Polycarbonate article sidebar. WWriter (talk) 04:21, 26 March 2011 (UTC)

No, it doesn't have the same properties. Someone in a library should copy the _data_ in a uniform way from one of the many reference books that use consistent tables, to the various resin articles. (Information can not be copyrighted- only the complete work that displays it.) This article is confused on many applications that predate the use of oriented film processing, when plain film was a big improvement over acetates and vinyls. (talk) 08:31, 23 March 2013 (UTC)

Replacement for celluloid[edit]

David Bordwell mentioned on his blog that mylar has been in use as a replacement for celluloid in 35mm film motion picture release prints - for about fifteen years now. Since this means that practically the whole analog film distribution/projection circuit relies on it, I find this a significant use that deserves a mention. Source: K37b8e4fd (talk) 22:59, 5 May 2013 (UTC)

Space Suits[edit]

I've removed "to keep astronauts warm" and replace it with "help regulate temperature." A space suit doesn't keep a astronauts warm, it keeps them from getting to too hot according to all modern literature. Some early books on the subject do claim the suit is to keep them warm but that was incorrect. — Preceding unsigned comment added by (talk) 01:05, 6 April 2014 (UTC)

Other use of BoPET/Mylar[edit]

One important, current use of reflective BoPET is for indoor plant growing, as it is cheap and easy to cover the walls of an enclosure or room to reflect more available light to the plants. This is especially useful when trying to grow plants indoors but conserve as much energy as possible, as it allows for maximum light coverage if all internally-facing sides of an enclosure are covered. Examples would be a "grow tent", "grow closet", "grow box". (talk) 13:34, 21 October 2014 (UTC)