Does anyone know where to find R&G products in the US? Their epoxy is
very good for building composite aircraft. Lots of information on the
website: http://www.r-g.de/en/
As for whether or not curing will enhance the properties of any given
epoxy, it would be easy and fast to do a test on identical samples where
one is cured with heat and one is not.
Jimmy
[EMAIL PROTECTED] wrote:
Are you completely set on using West? As I recall (although I don't recall where
the numberrs come from) West System doesn't develop properties with post
curing as nice as some other epoxies. For instance, I have an epoxy mix picked
up from a boatbuilder I know which has a considerably higher glass transition
temperature after post cure. ( but again, it's been so long I don't recall exactly
what those properties or cure temps are).
For a small job like this, I'd probably use Phase Two from an outfit called System
Three. You will get a paper telling you exactly how to postcure it. (Two hours at
140F, but it has to be that warm all the way through). An unusual property is
that it becomes relatively opaque because of the two phases, which are
supposed to make it tougher than a singly phase epoxy. Not sure if this works
in terms of strength and toughness, but it handles ok. Heat deflection temp
claimed as 64C (147F)
For a big job I'd go back to that boatbuilder I know or else look into Raka as
mentioned below.
If I thought the volume was going to be pretty high I'd definitely look into
prepregs. Probably save a lot of labor and get better properties too, although I
haven't played with prepregs yet. Your oven might not be enough for them,
though.
I seem to recall MGS (sp?) epoxies are made for postcure as well.
You might try Raka. The proprieter is willing to talk to you on the phone, and
can recommend temperatures etc. for various epoxies he has.
If you pick the right materials and cure it right, you can use colors other than
white, although I certainly wouldn't do it with West.
If you must use West, it sounds like 120F for 4 to 8 hours is good. I found it in
the following newsletter from West:
http://www.westsystem.com/ewmag/18/pdf/tanks.pdf
Now, some of that epoxy is mixed slightly different, but not much.
Don't exceed 140F:
http://westsystem.com/webpages/userinfo/moreinfo/coldtemp.htm
(that's a clue that you may not get great thermal properties)
Note that, according to the physical properties on the West site, 105/206 is only
good for 123F heat deflection temperature. That's why we need to keep it white!
I think, given the labor involved, that if the results are important it's a false
economy to use the epoxy on hand. Nothing wrong with WEST if you aren't
going to use the result in high temps or need really high properties in the resin.
In that case I'd use the ordinary version of RAKA because I've used it with good
results in the past and it was cheaper.
I realize that you probably have 10X the practical experience laying up glass
stuff that I have, but I've looked into the post curing thing a little bit.
Even if you stick with WEST, if you get it to 100F overnight it will be reasonably
well cured overnight. But I understand post curing works best AFTER the initial
cure.
Bill & Bunny Kuhlman wrote:
Granddaughter Alyssa and I are involved in vacuum bagging processes:
carbon fiber spar caps, fiberglass over foam flying surfaces, and a
molded all glass fuselage pod and boom.
We're using West System 105/206 for all of the components.
We know that post curing - higher than room temperature heat over
several hours to a full day - will make the epoxy matrix stronger,
but after a long web search have been unable to get firm numbers for
either the temperature required or the recommended time period.
If anyone can pass on this information, we'd very much appreciate it.
We have our "hot box" made and can take it up to 160 degrees F.
Many thanks in advance!
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