Originally Posted by
ckelloug
Sandi,
I looked at your epoxy the other day but until getting the Reichhold formulation, I wasn't really sure what to compare it to. Comparing the fluxral modulus of yours vs. the Reichhold stuff, your R&G epoxy is 2730MPa while the Reichhold stuff has flexural modulus of 4900MPa. Given all things equal, your epoxy will deflect about 30% more that the stuff Walter et. al are using when formed into a beam. The viscosity of your R&G epoxy is 1600 cps while the epoxy from Reichhold is only 600 cps, (I assume the epoxy is similar to the hardener but may be wrong). An cps (centipoise) is equal to an mPas which is a milli-Pascal second. From wikipedia water is 1 centipoise in viscosity while motor oil is 250 cps in viscosity.
I believe your epoxy is about 3 times as viscous as the stuff from Reichhold and it also seems to be much faster curing. They show the R&G stuff being cured overnight at room temperature and 10h at 70C. The Reichhold data sheet shows theirs being cured overnight at room temperature and 2 hours at 120C or 7 days at room temperature.
A 4 inch square beam 48 inches long made from your epoxy cured according to the data sheet with a 100 lb load placed in the middle would deflect .027 inches while the epoxy Walter is using would deflection .022 inches. This does not reflect the addition of aggregate or particles.
In short, your epoxy is more viscous and faster curing with slightly lower strength than the stuff Walter et. al. are using. There is no reason however that you can't make serviceable parts with it, it may just require different processing to avoid air bubbles, slightly larger members to avoid deflection and perhaps slightly different aggregate design. Unless you are engineering your stuff to really tight tolerances all this is to say the difference probably won't matter except in ease of mixing.
I am very very far from expert at this, but I hope this helps.