Substitute for EPON 828? 3

[KirbyWan]

Howdy all,

I am trying to find a material substitution for EPON 828. This is to repair a DC-10 antenna panel which is a laminate honeycomb core panel made from 250°F cure prepreg fiberglass. The DC-10 SRM 51-43-01 provides a wet layup repair using EPON 828 or Hetcon 92. I want to use the same process only with EA9390 adhesive and cure cycle similar to B757 SRM 51-70-17.

The problem I am having is finding data on these old adhesives. The Epon 828 data sheet is very short on strength properties. It can be cured with dozens of different curing agents and it lists the strenght of up to 10000 psi without mentioning which curing agent was used. I can't find any information on Hetcon 92.

Does anyone have recomendations for how to substitute materials? I can't really do a test since I don't have Epon 828 data to compare against. There is plenty of data on EA9390 from Henkel and in BMS 8-301, but what do I compare it to.

Thanks to the community for pointing me in the right direction.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[rb1957]

yet a decade ago we were just about swilling the stuff ...

 

[KirbyWan]

Yeah, OSHA has added rules to limit the number of radioactive spider bites that are permissible per 8 hour shift. It's not like in the old days.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[berkshire]

Kirby
I realise this may be taking you off to where you do not want to go.
Miller does sell TETA. this hardener at 11 to 13 parts per hundred will give you a room temperature cure that can be post tempered up to 180 degrees F and give you the strengths you are looking for.
Back in the 70's I used to practically bathe in this stuff.
In the 80's I got an MSDS sheet with an order of TETA and nearly had a heart attack when I saw what it could do to you.
Even this stuff is a pretty aggressive hardener, however,
this was an approved room temp resin system for several aircraft Mfrs in the 70's Unfortunately I have discarded most of those old data sheets. The only old Boeing document I have is D6-24483 for the 767 ( 1985)
Which lists Epocast 956 and 9449 hardeners
Which I do not think will help you. I think you are dealing with an old DPS spec which Boeing has now taken over.
You may have to break down and ask Boeing for help on this one.
B.E.

 

[KirbyWan]

I found enough property data comparing a wet lauyp of EA9390 with fiberglass to the DPS spec for the original prepreg fiberglass layup to comence the hand waving that this is an acceptable substitute. It's not as rock solid as I would like, but with my experience of EA9390 I feel confident that the repair is structurally sound. I did an earlier comparison of EA9390 wet layup with carbon fiber and hit an average of 118 ksi. This is a good resin system.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[rerig]

Maybe this will help with the "Warm Fuzzy".

 

[berkshire]

rerig,
I gave you a star , that document is 4 years younger than mine.
B.E.

 

[KirbyWan]

Thanks, Rerig,

That'll help if someone second guesses my repair. And i can go through that and get a real idea of how strong it really is based on a whole slew of data. Excellent, a Star for you.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[rerig]

A little more research revealed that Epon 828 is DMS1688.
However, It isn't very helpful. It doesn't show strengths for different hardeners.
My copy is from 2003. 3 Pages.

Exerpt:
4. TECHNICAL REQUIREMENTS:
4.1 Mechanical and Physical Properties: The properties of a laminate, tested at 70-85F, shall be as specified in MIL-R-9300, Type 1, in addition to the following elevated temperature requirements when tested lengthwise at
300F ±10 after aging for 1/2 hr at this temperature:
Flexural, Flatwise, psi, min
Ultimate Strength, 40,000 psi
Initial Modulus of Elasticity 2 X 106
Ultimate Compressive Strength, Edgewise, psi, min 20,000
Ultimate Tensile Strength, psi, min 30,000

4.1.1 Barcol Hardness:: The Barcol hardness of the laminate fabricated as specified in MIL-R-9300 shall be a minimum of 60. Size of specimen shall be in accordance with Fed. Test L-P-406.

 

[KirbyWan]

Rerig,

Yeah I found that spec and read through it, but it didn't have any useful property data that I could compare. I didn't have any flexural flatwise data on EA9390. For that I had flatwise tension, but no info on the Epon 828 for flatwise tension. It's like they purposely avoided providing any datum point that matched up between the two adhesives.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[rerig]

EA 9390 is BMS 8-301.

I should read the intent of problems first. I gave you all I had on Epon 828, but, why not repair per DC-10 SRM V-II 51-62-01, GENERAL REPAIR OF ADVANCED COMPOSITES.
Using Table 1, Sh 2 (EA9396 - DPM 5535-5).
Cure 1 Hr at 150F.
EA9396 Attached.

 

[KirbyWan]

I looked at that, but it said '... to be used with the specific repairs included in this structural repair manual.' and this part is not listed in the SRM. It's not even listed in the IPC. I was tempted, but I wasn't sure it would apply. I also wanted to use EA9390 since I feel it is a better repair material then the RT cure adhesives.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.