Compoflex RF150

General Composites Discussions Composites Talk
#1

I’m planning to infuse a small three layer CF laminate (one layer of 10 oz uni followed by two layers of 7 oz 2x2 twill). The laminate is flat and approx 15 inches in diameter with a 1/2 inch lip around the perimter. After reading some posts on here I think I’m going to try Adtech’s 820 infusion epoxy (unless you guys recommend another infusion epoxy that will cure at RT) with Compoflex RF150. My question is this: Is it acceptable to use a layer of peel ply (red stripe for example) between the laminate and the Compoflex? The only reason I want to use the extra peel ply is to get a smoother finish on the laminate AND because I dont think the Compoflex will conform to the 1/2" lip around the perimeter of my laminate (the lip is angled outward approx 45 degrees). I should note that I’ve only used the Compoflex SB RF 150 before and it left a VERY rough surface (which by the way MUST be sanded for a good secondary bond… I found that out the hard way!). My plan is to (a.) lay the laminates, then the red stripe peel ply over the entire laminate, then the compflex, then bag -OR- (b.) lay the laminates, then red stripe peel ply JUST over the 1/2" lip + 1/2" or so each side of the lip, then the compoflex over everything BUT the 1/2" lip, then bag.

Any advice appreciated!

BTW: I have some VE infusion resin that I could use but I’ve heard VE doesnt wet out CF very well so I’m spooked to use VE on this part.

#2

Yes, it is perfectly acceptable to use peelply below Compoflex 150RF. I do not see any problems.

About using VE with carbon: Why not? You are the first one telling me it will not impregnate. Do use an infusion VE, however. Hand laminating VE (and UP) are thixotropic, and will not infuse well.

#3

herman, most carbon is not sized for VER, but for epoxy. carbon will wet out as long as you have a slow flow, and a good resin. HOWEVER, the resin might not bond to the fibers, and can delaminate, and fail very quickly. Cutting is an issue, because fibers may fray, depending on fiber/resin content and cutting method.
Depending on what the part is, it might not matter at all. Depending on the fiber sizing, it might be ok for VER (hybrid, etc)

#4

Thanks Herman & Riff! The purpose of th laminate is to stiffen an area on the wing of a low wing experimental aircraft next to the entry point into the xxxxpit where the inner layer of wing skin & 1/2" foam core has been removed to allow the main wheels (retractable) to tuck up a bit tighter (quite a few other owners of this same model aircraft have made the same mod but they’ve used regualar e-glass to closeout the area where the inner layer of skin/foam core have been removed). I’m using CF becuase it’s not only stiffer but I plan on clear coating the laminate to show off the CF for anyone inspecting my work close enough to peek up in the wheel well from beneath the wing) The wing skin is composed of (from outer to inner) 4 layers of e-glass - 1/2" foam core - 3 layers of e-glass. The area where the inner skin has been removed is aprox mid way between the trailing edge of the wing and the wing spar. NOTE: When I say “stiffen” the purpose is merely to prevent someones foot from flexing/cracking the skin in this area when they stand on the wing to get in/out of the xxxxpit. The VE resin that I have is special infusion VE (very low viscosity) that uses a different cataylist (not MEPK) to reduce the tendency for the resin to boil under vacuum. Your thoughts?

#5

That special catalyst (which is not catalyst, you crazy Americans :)) is a Cumyl hydro peroxide, which is (as good as) free from H2O2. It is the H2O2 which react with the VE, and causes bubbling.

I have a very slow MEKP/CHP blend, which does bubble somewhat, but only the first 5 minutes or so. After that it is stable. And it gives nice long geltimes, and a thorough cure.

On sizings: I should look it up. Most over here is regular silane sizing, for EP, UP and PH

#6

Most sizings that are used on carbon fiber are composed of epoxy. There are some newer urethane based sizings that have been developed specifically for interfacing carbon fibers and vinyl ester. It usually has to be special orders which equals $$$$$$$.

I don’t think silane sizings works with carbon fiber…I could be wrong though.

#7

Sounds correct, glass is sized with silane, carbon with epoxy