Charles Smith wrote:

Group,

I have data for a four day immersion on two different epoxy

samples

in

oxygenated fuel.

Sample 1 was pure Aeropoxy PR2032/PH3660 resin cured for at

least

three

months at room temperature.
Sample 2 was an epoxy/glass laminate coated with Jeffco 9700

(supplied by

Bill Schertz).

Both samples were nominal 1X1 inch squares.  The fuel mixture

was

ASTM Fuel

C/Ethanol blend 85/15 by volume.  ASTM Fuel C is a high aromatic

fuel blend

intended to simulate premium gasoline and is 50/50 (v/v)

iso-octane

and

toluene.  The ethanol was added at 15% to make the fuel mix as

aggressive as

it gets.  Only methanol blended at this ratio would be worse.

After four days, the pure Aeropoxy volume changed by +12% and

its

weight

changed +9%.
The Jeffco sample volume change was +10% and its weight change

was

+5%.

If these samples were elastomers, I would think the results

quite

good; on

the order of what I would expect to see using 70 Shore A

durometer

fluoroelastomer.  However, they are materials which should have

considerably

higher crosslink density than elastomers and I could hope for

better

results.  I am not raising any red flags.  The fuel mix is

extremely

aggressive and represents worse case and these are quite low

volume

changes.

I haven't tested avgas yet and would expect much, much milder

results.  I

have put the samples back into the fuel mix and will pull them

out

when they

reach one month duration and measure again.

I did speak with Scott the tech service chemist at PTM&W and he

tells me

that the Aeropoxys have not been tested or certified for fuel

contact.  He

advised coating tanks with a polysulfide sealant and I have

asked

them to

mail me their literature on coatings they recommend.  I'll be

happy

to share

that with the group if any are interested.

Charlie Smith
Cruiser 4021

I am interested in the epoxy / fuel compatability issue, am using PTM&W

for

structure of the Cozy and am using West Systems for the fuel tanks.  I

ran a

test on the West Systems using regular gas and the reformulate gas used

in

Texas (which should be banned from the earth) with no degradation with
either type of fuel.  If anyone can test for alchol compatability of the
West System (used in the marine industry), I would really appreciate it.
Wendell Voto

Which West Systems epoxy do you use for tanks?

Thank you

Jerzy

 
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