GRP vacuum container?

Discussion in 'Materials' started by idkfa, Mar 6, 2012.

  1. idkfa
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    idkfa Senior Member

    Is it possible to make a vacuum cantainer with PE & mat that will keep a vacuum for 20yrs plus? Sure it will do it over a couple of days but fibreglass in porous and even to water? So how long it contain a vacuum?

    Guess gel-coated surfaces and resin rich mat will help?
     
  2. gonzo
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    gonzo Senior Member

    To start with, what kind of negative pressure do you need? Perfect vacuum is not attainable.
     
  3. idkfa
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    idkfa Senior Member

    12psi would be sufficient.
     
  4. gonzo
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    gonzo Senior Member

    FRP has solvents that will evaporate slowly. That will lower the vacuum with time. A metal or glass container would be more appropriate.
     
  5. idkfa
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    idkfa Senior Member

    thanks,
     
  6. rwatson
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    rwatson Senior Member

    20 yrs is a long vacuum time. Are you preserving something ?
     
  7. idkfa
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    idkfa Senior Member

    thermal insulation, have switched to epoxy.
     
  8. rwatson
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    rwatson Senior Member

    Interesting concept. How much better is it than say thick styrofoam, especially costwise.

    Is it a big area to keep cool ?
     
  9. waikikin
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    waikikin Senior Member

    I'm interested too, what's the application re thermal insulation? Maybe it's gotta be extraordinarily strong to resist? Jeff.
     
  10. SamSam
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    SamSam Senior Member

    It might depend on what you are using it for and how you go about making it. With a constant vacuum inside, meaning constant pressure on the outside, I would imagine over time a fiberglass surface will deform. So if you were to use it for walls, after awhile they might look bad, used hidden or where looks didn't matter, like a fish hold, it might be OK.

    http://en.wikipedia.org/wiki/Vacuum_insulated_panel

    Things like these...[​IMG]
    http://www.panasonic.com/industrial.../vacuum-insulation/vacuuminsulation-group.gif ... I believe start with some sort of inner structure like foam etc. They aren't hollow like a "thermos" type liner, so any possible thermal advantage should be balanced against weight and cost, in that you would have the weight of a foam core plus the extra weight of skins strengthened against the vacuum.
     
  11. Stumble
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    Stumble Senior Member

    Vacuume panels apparently are significantly better at insulating than insulating foam, or synthetic foams. From what little I found, they have R values more than 10 times better than the best insulating foams, so I would guess would be far superior to typical core foams. That being said they are very expensive relatively, so you get about the same R value per dollar spent.

    I can't see their application in a boat due to their major limitations in shape and size, but it might be possible to design a double hulled structure with them... But it seems like the cost would far exceed the cost to assume lower R value and just install larger HVAC systems.
     

  12. Herman
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    Herman Senior Member

    In industrial applications vacuum insulation is used sometimes. However this is many times used in very high or very low temperatures, where composites do not perform.

    I have once been asked to calculate a vessel, fairly large. It was reckoned that a vacuum pump would need 3 days to evacuate all air. (moleculair turbine pump)
     
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