1. posterid:2320973
  2. Recommended Epoxy System?

Re: Recommended Epoxy System?

Larry Severson
 

I am working a unique system that involves a heat box w/fan and smaller parts up to 6.5 ft long, not a complete Q2.

 

Larry Severson

18242 Peters Ct

Fountain Valley, CA  92708

(714) 968-9852

 

From: Q-LIST@... [mailto:Q-LIST@...]
Sent: Saturday, August 29, 2015 3:18 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Re: Recommended Epoxy System?

 

 

Larry,

 

Post cures need to be controlled events. It is very difficult to follow a post cure schedule and keep the whole structure even temperature. That is why I use Aeropoxy and get a Tg over 150F. No need to post cure and take a chance of ruining your structure.

 

Your method will leave the structure with areas that the Tg increased and areas where it did not increase. Maybe if you build a giant rotating fixture and spin it the sun can heat the whole thing.

 

Regards,

 

Charlie Johnson


On Aug 28, 2015, at 12:35 PM, 'Larry Severson' larry2@... [Q-LIST] <Q-LIST@...> wrote:

If you go to vacuum infusion using the PTM&W (2712) epoxy, the Tg can be raised to 212 degrees F. But that requires slow post curing cycles. That means raising the temp 10-20 degrees in at least 2 hour cycle periods. Every time you take the plane out of the hanger, if the temp is above the initial curing temp, the Tg will be raised, as long as the new temp is higher than the previous time. Unfortunately, if the plane is exposed to above Tg temp at any time, the plane is subjected to epoxy delinking and plane sag.

 

Each epoxy has a different ultimate Tg.

 

Larry Severson

18242 Peters Ct

Fountain Valley, CA  92708

(714) 968-9852

 

From: Q-LIST@... [mailto:Q-LIST@...]
Sent: Friday, August 28, 2015 10:44 AM
To: Q-LIST@...
Subject: Re: [Q-LIST] Re: Recommended Epoxy System?

 

 

I'm not Charlie, but I've done quite a few
postcuring tests and DMA/DMTA Tg tests on epoxy
systems in various projects. I always saw a
definite upper limit for an epoxy system, no
matter what postcure cycle. Quite often they were
amazingly low, like 80 degrees Centrigrade for
low-viscosity vacuum-injection systems.

Rob

At 19:11 28 08 2015, you wrote:
>Thanks Charlie,
>
>Can you tell me, does Tg rise each time the
>ep oxy gets heated to a higher temp than the prior heating?
>
>Cheers,
>Jay
>
>

 

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