Is polycarbonate reactive to plasticizers?

Discussion in 'Workshop Tips and Secrets / Tools' started by davidb, Jan 26, 2019.

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  1. Jan 26, 2019 #1

    davidb

    davidb

    davidb

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    I’d like to try using one of the various cling vinyl sun shades on a polycarbonate canopy. I gather there is quite a bit plasticizer in the “vinyl” which might actually be pvc. I’m at a loss trying to decipher all the possible chemicals used as plasticizers and their effect on polycarbonate. Any chemists or folks with practical knowledge of the issue?

    I am particularly interested in the “cling vinyl” type of sun shades because it would also serve to protect from my headset marring the canopy. My primary motive is to protect the canopy from getting scuffed from my headset so any ideas on that is also welcomed. I’m considering putting something like moleskin on my headset if the cling vinyl is no good. Thoughts?
     
  2. Jan 27, 2019 #2

    pictsidhe

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    PVC: Polyvinyl chloride. Yes, PVC is Vinyl. Sorry, don't know about the plasticisers.
     
  3. Jan 27, 2019 #3

    pictsidhe

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    I'll likely be making my canopy and screen from thin PETg. I can't find a UV stable one, but one manufacturer suggests spraying with clear UV blocking lacquer. A tinted one may be good for you.
     
  4. Jan 27, 2019 #4

    proppastie

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    Used cling vinyl on polyester windshield (Plexiglas) no problem
     
  5. Jan 27, 2019 #5

    wsimpso1

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    Consulted the materials scientist in the house (career in polymers) and she says you should be concerned about applying vinyls to polycarbonate. I would not gamble on that... That being said, some folks get away with it because some polycarbonate sheets have a thin acrylic coating for scratch protection. If you can know if your canopy had an acrylic layer and can know which side it was on, then you might get way with it.

    Billski
     
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  6. Jan 27, 2019 #6

    wsimpso1

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    Consulted with the materials scientist on this one as well. Maybe you can use cling vinyl on polyester or Plexiglas without problems, but polyester and Plexiglass are different stuff. Polyester usually makes lousy transparencies. Plexiglass is PMMA, poly-methyl-methacrylic, makes excellent transparencies, and is very different stuff from polyester.

    Billski
     
    Last edited: Jan 27, 2019
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  7. Jan 27, 2019 #7

    Dan Thomas

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    The polycarbonate windshield and canopy in my Jodel crazed after a few months with a new vinyl cockpit cover on it. The vapors from the vinyl did it. Plasticizers? Maybe.

    I also know that the non-chlorinated brake cleaner, which is safe on most plastics, attacks polycarbonate.
     
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  8. Jan 27, 2019 #8

    proppastie

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    was the Mooney side window, Plexi or generic, sorry about wrong polyester designation. should have said acrylic.
     
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  9. Jan 27, 2019 #9

    davidb

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    Thanks guys! I’m glad I asked. No cling shades for me. I got new canopies as part of my hail damage repairs and don’t want to do anything to harm them. I’m still wondering why my old ones cracked and now I might have an idea of a contributing factor:

    The hull is composite and the resin used might be vinyl ester. Also, lots of vinyl and plastic in the interior. When new, the plane sat in the sun a lot with the canopy closed. I remember noticing the strong “plastic” smells when I would open the canopy. Perhaps that was enough to weaken the polycarbonate to the point where the hail could do damage?
     
  10. Jan 27, 2019 #10

    Dan Thomas

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    Easily. My fuel filler is in front of the windshield, and the polycarbonate was the original from restoration 16 years before and getting old. I had used vinyl covers on it from time to time. One day I splashed some fuel on it and it shattered, totally unlike polycarbonate. I made a new windshield, moved to a new job where I didin't have my hangar anymore and parked it in the open with the old vinyl cover over it. Everything was fine for about three years until I made the new cover, and the outgassing from the new vinyl crazed it.

    I've been told that using ammonia-based cleaners (like Windex) on polycarbonate will wreck it, too. I never used anything but Lemon Pledge. Didn't seem to hurt it much.
     
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  11. Jan 28, 2019 #11

    proppastie

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    too late for OP but all the certified I know use acrylic......do any certified use polycarbonate? It is reported poor UV characteristics, which make me wonder about all those polycarbonate building windows ( that seem always to be a milk white ?)
     
  12. Jan 28, 2019 #12

    Dan Thomas

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    I've never encountered anything but acrylic in certified small airplanes. Heavy glass for the windshield in some larger aircraft.

    An awful lot of older homebuilts had flat-wrap windshields and canopies. Acrylic needed to be carefully heated and draped over a form, and some guys would have to build some sort of oven big enough to do this. Acrylic doesn't like being bent too much. When polycarbonate showed up (we usually referred to it as Lexan, the trade name given to it by its inventors, General Electric), homebuilders sudenly had a material that was real easy to cut and drill and bend. If you treated it about like aluminum you were safe enough. You could saw it or drill it. You could bend it like sheet metal in a bending brake. But it has its disadvantages: it is softer and scratches easily, and some chemicals attack it. However, those of us who used it found that its ease of fabrication outweighed the possibly shorter life compared to acrylic, especially considering the fabrication hassles with acrylic.
     
  13. Jan 28, 2019 #13

    lr27

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    I'd rather have a fresh polycarbonate windshield in front of me than acrylic if there was going to be a bird strike. That stuff is tough. There are polycarbonate sheets that are sold for use in windows. Maybe that grade lasts longer? Polycarbonate is easy to work. The only time I ran into trouble was when I used an aggressive feed rate, so that it melted and grabbed the band saw blade, breaking it.

    For those who are really paranoid about bird strikes and have deep pockets, I understand that there's a transparent aluminum ceramic that's actually bullet resistant and hard to scratch. I don't know if you can bend it, though.

    Properties are good enough that you could probably make Wonder Woman's airplane with it. Might not even weigh more than a regular aluminum airplane, though somehow I think the price would be much higher. Might make preflights easier.
     
  14. Jan 28, 2019 #14

    pictsidhe

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    Transparent aluminium cerámic is more commonly known as "sapphire". You'll need to be lying down when you price a sapphire screen.
     
  15. Jan 29, 2019 #15

    lr27

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    It's supposed to be synthetic spinel, not sapphire. One brand name is ALON. Harder to scratch than glass, but not as hard as sapphire. Definitely NOT sapphire.
     

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