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Old 01-01-2012, 09:11 AM   #1
katmandu

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Default Use of Henkel Synspand in heat cured vacuum bagging

Hi,
question with regards to Henkel Synspand. Since Synspand expands to 200%+ @ 250F; will it increase my prepreg laminate compaction when I use it in conjunction with vacuum compaction and heat?

I'm looking at ways to increase compaction pressure in addition to vacuum bagging.

Anyone tried this before? Are there any other ways to increase compaction in addition to vacuum bagging? Autoclave is out of the question.
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Old 01-01-2012, 10:22 AM   #2
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Um.... Isn't that just an expanding adhesive? It's generally used to fill the void between laminate and core. And or sloppy core splice surfaces. It will not increase compaction.

All it does is goop up under vac and heat for a better bond than a traditional film adhesive. As far as it intensifying pressure.... No.

Double bag with caul plates and breather is the exception. Search Capri lite.
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Old 01-01-2012, 11:20 AM   #3
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Quote:
Originally Posted by katmandu View Post
Are there any other ways to increase compaction in addition to vacuum bagging? Autoclave is out of the question.
I use bladders at 40 to 100 psi to increase compaction. I'm producing a high performance structural part right now that is getting 75:25 fiber to resin by weight.
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Old 01-02-2012, 02:31 PM   #4
Wightmarine

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You might find "Expancel" of interest it is heat activated and it expands 20:1 at 80-100C

Bladerunner posted some info here about it a while back for curved tube manufacture pressure of 100psi + contained in a bladder looks interesting .

http://www.compositescentral.com/showthread.php?t=5872
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Old 01-09-2012, 12:20 PM   #5
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thanks for your input. I'll check into the Expancel product. Looks interesting.
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Old 01-10-2012, 05:43 AM   #6
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I checked with the German distributor of Expancel a couple of days ago and he was quite surprised to hear it used for this purpose. The minimum quantity is 300 kg, which would last a lifetime for me.
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Old 01-10-2012, 08:03 AM   #7
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If you are doing vacuum bagging in our atmosphere, nothing will increase compaction except rising outside atmosphere pressure (which I hope you cant do ). If you use expanding stuff on top of your prepreg layup and cover it with vacuum bag and pull vacuum it will not increase pressure on your layup when that stuff expands. Max you can theoreticaly reach is 1 atmosphere (exact value depends on your altidude). Rest will just rise the vacuum bag.
Thats why you have to use autoclave or something similar (rubber membranes compressed with hydraulic pressure, etc.).

Expanding stuff will increase pressure on your layup only if its in closed space. You can google trapped rubber tooling and similar things. With trapped polymers you can have extremly high compacting pressures. But there are lot of different problems with this like uneven pressure when core is not designed correctly. With this technology you can produce hollow one piece aerodynamic wings for cars for expample.
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