Resin cure time under vaccum

Discussion in 'Fiberglass and Composite Boat Building' started by sadiq, Oct 2, 2014.

  1. sadiq
    Joined: Oct 2014
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    sadiq Junior Member

    I am working on a project to make a blade with fibre that has to be impregnated by resin under the action of vacuum. the resin has to be cured under vaccum pressure (no atmospheric air).
    we had a try, and the resin is didn't cured well even after 24 hours.

    Tell me is atmospheric air necessary for curing?
    tell me how to reduce cure time for resin under vacum?
     
  2. gonzo
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    gonzo Senior Member

    What kind of resin?
     
  3. sadiq
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    sadiq Junior Member

    555 resin
    alkhair manufacturer
     
  4. sadiq
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    sadiq Junior Member

    and please tell me any book that is available in internet that tells the basic of resin types, fibreglass types, curing, etc
     
  5. gonzo
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    gonzo Senior Member

    alkhair doesn't seem to have a website. Their name appears in Alibaba under textiles, resins and other miscellaneous stuff. I suggest you contact them if the resin was delivered without technical data.
     
  6. AndySGray
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    AndySGray Senior Member

    The polymerisation process is the same with or without vacuum - if you used the resin and hardener without the vacuum it would still set if mixed correctly.

    It is a little more tricky as you have to get everything together before the resin mix starts to go off, if this happens with hand layup you simply stop at that point.

    many folks us a digital scale to weigh the ingredients (put it in a Zip Loc bag) - will give you a very consistent (repeatable) mix.

    The other factor is heat - we used to refer to a Q10 factor - basically it means that the time taken to harden will half with every 10 degrees (celcius). You can use that to your advantage if you do some carefull planning.

    If you have a mix which starts to go off in an hour and your layup takes an hour and a half, you can either weaken the mixture and risk incomplete polymerisation... OR you get in to the workshop a couple of hours before dawn when all is nice and cool, do the lay-up at a nice relaxed pace, finish it off, bag and vacuum it. Then pop it out in the sun to warm up and go for a nice leisurely breakfast - when you come back it will be warm and well on the way to being cured.

    The vacuum helps to compress everything together, it also pulls out gas bubbles and air pockets, and will remove some of the volatile solvents - all of which helps to make for a strong and high quality job, but don't expect it to significantly change the curing time for a given mixture.
     
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  7. Steve W
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    Steve W Senior Member

    It sounds like you are using resin infusion, if so and the resin did not cure i would guess that someone forgot to mix it, resins, be it PE,VE or epoxy will all cure properly under vacuum.

    Steve.
     
  8. rxcomposite
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    rxcomposite Senior Member

    Strange. Over here 555 is a very popular sardines.;)
     

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  9. Landlubber
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    Landlubber Senior Member

    Sound like simple vacuum bagging really, but you have to use current date resins, and check the hardener too mate as old stock sometimes does not go off as expected.
    Try again with the correct ratios and see what happens.
     
  10. gonzo
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    gonzo Senior Member

    You should try a small sample to make sure curing is correct. That way, if something goes wrong, you don't lose a lot of money and materials.
     
  11. sadiq
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    sadiq Junior Member

    http://alkhair.com.pk/
     
  12. sadiq
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    sadiq Junior Member

    what should be the cure time ?
     
  13. Steve W
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    Steve W Senior Member

    LL, "fiber that has to be impregnated with resin under the action of vacuum" sounds more like resin infusion than vacuum bagging to me. Perhaps the op can clarify, although it does not matter really, any resin that is properly mixed at the correct ratio will cure under vacuum.
    To the OP, the time it takes to cure is resin specific, PE or VE will cure in just a few hours, epoxy takes much longer and also depends on which hardener you use as most epoxies have 2 or 3 different choices. 18 - 24 hours would not be unusual. You need to find the answer from the resin spec sheet.

    Steve.
     
  14. sadiq
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    sadiq Junior Member

    we don't have any specs sheet. the shopkeeper/supplier gave us the resin, hardner and cobalt. when we mixed cobalt(a single drop), it hardened during mixing.
    our method is resin infusion (means that we suck resin into fry fibreglass through vaccum) and not vaccum bagging( which is used to compress the wetted fibreglass to remove excessive resin).
     

  15. gonzo
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    gonzo Senior Member

    Without spec sheets, you have to make your own. However, unless you spend a fair amount of time and money, you won't be able to guarantee the quality of the product. What you are asking is akin to "how long is a string?". Unfortunately, we can't help you without specifications on the resin. Go back to the seller and ask for them.
     
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