Polyethylene sheeting and heat 1

[casseopeia]

I've been looking for some information about what effects service temperature will have on polyethylene sheeting (probably 6 to 10 mil thickness). It's to be placed under hammered copper panels that are attached to a structure. I'm guessing temps will range 30 degrees F for low and 250 degrees F high.

Any good resources or websites out there?

 

[rnd2]

I can say from experience that it would be best to avoid PE pretty much anywhere above 75 deg.C unless the load requirements are neglible. Above 100 deg. C forget it.
If it is available PP might be a better choice as it has a higher operating temp, around 100 deg. C, than PE. Mylar will bear load and has an operating temp around 150 deg.C and is dimensionally stable, whereas neither PE or PP is dimensionally stable at temp. Mylar is available in the thickness you nominate. Mylar is thermoset polyester film and is a brand name of Dupont.

 

[IRstuff]

Another possibility is Kynar, which is used as a coating for roofing and siding materials.

TTFN

 

[casseopeia]

Thank you both for excellent suggestions!

IRstuff, the possibility of using a Kynar coating falls under the "Geez, why didn't I think of that?" I used a similar specification on an armory years ago. It's actually more economical than it sounds. I had considered a Teflon coating, but I think Kynar is far better and no doubt less costly.

Later yesterday, I stumbled on a website for medical equipment that had pdf charts of the physical characteristics of various plastics. It's a good, concise synopsis that clearly shows that the use of LDPE would be foolhardy in this application. I downloaded the charts, printed them in color, wrote the chemical names for each of the plastics (OK, I had to Google PMP and PFA), and circled the important data, then gave it to the lead architect.

She was amazed and pleased, and this is someone who is not easy, if not impossible, to please. She'll be happy until she realizes all I've provided is what should NOT be done. But you guys have given me the #2 punch, possibilities for what CAN be done. Thanks again!

And if you are interested in the website with the charts, here's the link. Look down at the bottom of the page. There are about 4-5 lines describing "physical properties" and "chemical resisitance A-G" etc.

http://www.dynalabcorp.com/technical_info_ld_polyethylene.asp