Epoxy - physical properties

General Composites Discussions Products Talk
#1

I’ve been searching for a great epoxy with some certain properties.

It will be used for infusion so it needs to be 700cps or higher.

It needs to be clear, not amber or dark color.

I’d like it to be hard, at least Shore D 75, preferably higher.

The shear strength to be 3,500psi or more.

Also non-blushing (cycloaliphatic) hardener.

Room temp curing.

The resin i currently use is a tad thick for infusions @ 600cps 70F. Also it’s a bit too flexible, like it’s not hard enough. perhaps i should be weighing out each component before mixing, i do it by volume instead. The Shore D is 70-75. The shear strength is 2500 psi. Modulus of elasticity is 5.7x 10 to the sixth power.

#2

Isn’t 600 cps thinner than 700cps?

#3

lol, i guess i should look that up. Ok so i’m not a scientist haha :smiley:

You’re correct, the lower the cps number the closer you get to a waterlike thickness.

so 600 cps @ 70F must be decent for infusion since i’ve seen infusion specific resins say they are 770cps A 70F.

Yep, my darn problem is vacuum leak. stupid &^% vacuum bag. I was thinking the resin was too thick to flow good. Ok my resin isn’t the problem, in fact on paper it looks really good for infusion and composites.

The problem i was having was the resin not being pushed into the mold from the resin cup. Later i ended up finding 3 vacuum leaks in my bag and one on a fitting to the resin pot.

#4

Hey, I have seen a lot of good epoxies form this company, but their site doesn’t work all that well, so oyu gotta call to get the numbers on their products. They look to have a lot of very specific resin system for a lot of different things. check out thier systmes and also the individual resin and hardener links, they have viscosities listed, some are really Thin!!

I’ve been wanting to try them, but I guess I will have to wait to use up all my current stock of resin.

www.jeffcoproducts.com

#5

I was sooo happy when i just demolded these c/f parts… they came out great, even with the vacuum leaks. That was a relief because i had to throw away two parts yesterday that didn’t infuse properly. That gets expensive throwing parts away.

#6

D*mn, JeffCo has like 25 different epoxy hardeners:eek:

I’m checking out that site now, i’ll see if i can get the spec sheets from them, and prices. Something is wrong with their server computer…it’s mega slow.

#7

For infusion, you’ll probably want a resin viscosity of 500cps or thinner, which would be a LOWER number. 400cps is good, but there are some epoxies out there around 200cps. Makes a huge difference when thin stuff is used!
As for clarity, it doesn’t matter at all. There is almost no resin on the surface, so it won’t be noticeable. We sometimes infuse with black resin, and the finished components still come out the same as with totally clear resin. Don’t choose resin based on the color.
You’ve mentioned that the parts don’t seem to be stiff enough. This could very well be due to a lack of post cure. It can make a flimsy part become rock solid. We use some epoxies that cure to a lower stiffness than our vinylesters at ambient temp. But when the epoxy is cured at 180*, it becomes orange (from light amber originally) and stiffness just about triples.

#8

I think you would be happy using the huntsman reninfusion 8604 resin system, check out the specs: http://www.nfgsales.com/files/active/0/RENINFUSION%208604_Ren%208604.pdf . I highly recommend it from personal experience. it is a clear blue hew transparent resin. shows carbon off nice, 370cps, very tough, room temp cure, decent TG

#9

sorry not meaning to hijack…

what is the difference between the “Tg” and the “Heat distortion” temp?

#10

Fastrr did you get in touch with them?

#11

I think it might just be the difference in testing method. I know to find Tg they will put a laminate in a machine and twist it under different temperatures to determine the Tg. I think Heat distortion temp test load the center of the laminate under different temps

#12

I see, but what does the quoted temperature tell me about the resin?

is that the max service temperature that it’s allowed to be exposed to?

if I have a Tg of 75celcius and I need to expose the composite to 100celcius what will happen?

what tells us the max temp that the resin can handle?

I’m just trying to make sense of this stuff, I thought I knew what it meant…

#13

Hojo, the specs read very nice on that epoxy combo. What type of hardener is that… amine? toxic fumes come from the hardener container when opened?

No contact with JeffCo as of yet.

#14

yes, when a laminate reaches its Tg it will change its shape and not go back. you would want to have a higher Tg then what your part will be exposed to. expect any part that sits directly in the sun to hit easily up to 150 degrees.

#15

yes, there is a nice toxic cloud that will emit from the container of the hardener apon opening. once mixed you cannot smell it. as with all epoxies always were gloves, even if your not allergic now you very easily can become allergic and it sucks. I have been allergic to epoxies for 8 years, so I always wear a pair of nitrile disposable gloves then latex on top of that.