Old 24th December 2012
  #1
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PMMA memrane?

Hi, everybody. I see quit often that some acousticians are using PMMA for membrane absorbers. This material looks pretty interesting but, unfortunately, there is almost no any information! Who have some information about it or maybe even expirience, can you share it?

PS: Sorry for my ugly english!)
Old 24th December 2012
  #2
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Old 25th December 2012
  #3
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There is quite a range of variability in PMMA. It's even worthwhile to look at Wikipedia:

http://en.wikipedia.org/wiki/Poly(methyl_methacrylate)

Scan down to the part that says: "modification of properties". That only hints at the range of property modification that manufacturers practice. The point I'm making is that PMMA can be very different from plexiglass. Then again, maybe plexiglass would work in a panel absorber?

When you look at PMMA membranes, a whole bunch of other properties begin to kick in because blends such as PMA with PMMA and the addition of a dense filler can yield a rubbery product that could easily be mistaken for a filled vinyl like LMV, just based on handling it. Much of the research over the last 15 years on PMMA membranes have involved chemical modification that leads to controlled porosity and other treatments that affect the hydrophylic/hydrophobic balance, behavior in acidic environments, etc.
Old 25th December 2012
  #4
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Quote:
Hi, everybody. I see quit often that some acousticians are using PMMA for membrane absorbers.
this seems interesting... do tell us some more... which acousticians? where have you seen it? there are many able investigators here... give us some leads...

Quote:
PS: Sorry for my ugly english!)
i love ugly things, but your english doesn't qualify...
Old 25th December 2012
  #5
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Quote:
Originally Posted by audiothings View Post
this seems interesting... do tell us some more... which acousticians?
Northward acoustics for an example. And so others too.

There is available some materials http://www.tela-design.com/en/produc...pmma-petg.html
But almost no information about using it in studio design.
Old 25th December 2012
  #6
Lives for gear
Quote:
Originally Posted by AP Productions View Post
There is available some materials Acoustic PMMA/PETG
But almost no information about using it in studio design.
I'm pretty sure the "PETG" in that is glycol modified polyethylene terephthalate. The PET part of that is basically a polyester. The material in the link looks like a rigid polymer so the PMMA part makes sense but I don't know what properties they are going for. I don't think of the material in that image as a flexible membrane as much as a rigid panel.
Old 27th December 2012
  #7
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RPG sells transparent absorbers. So does DEAMP. They have very limited absorption bandwidth and always require a air cavity to absorp. Only act at medium and a bit on high frequencies.

Quite useful to use on large acoustical spaces with lots of windows, no use whatsoever to use on a recording studio where you usually require broadband absorption
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