[brunog]

QED: "quod erat demonstrandum" or Quantum Electrodynamic ??

[lgalla]

Jonpry ask Bruno or Cam,I never joke.
I thought you were refering to FBE.
http://en.wikipedia.org/wiki/Fusion_..._epoxy_coating

[ckelloug]

Jonopry,

I don't agree with your proof. The reason that I don't agree is that Tg is not an intrinsic property of epoxy, it is an extrinsic one based on the temperature history of the cure. Thus, if you cure epoxy at low temperature you get a material with a low Tg and if you cure the same chemistry at a higher temperature you get an increased Tg.

Heating doesn't help cure epoxy by increasing the Tg, it helps cures epoxy the because it increases the rate at which chemical bonds are formed between either the epoxy and itself or the epoxy and the hardener. Heat works by increasing the amplitude of the motion of the molecules increasing the likelihood that they come into close enough proximity to react. This increase in motion also allows otherwise rigid networks of molecules to slip over one another and when the temperature gets high enough, the material is no longer rigid e.g. the glass transition temperature.

The following article shows how Tg increases with percent cure. Since heat increases the rate at which a given percent cure happens, it also increases the Tg at a given point in the cure cycle. This doesn't directly prove what I said but if you read enough epoxy datasheets about cure conditions vs. Tg, it can be shown empirically to be correct. I had another article showing how increased cure temperature increased Tg in IPDA cured epoxy but I left my only copy at my lab.
http://findarticles.com/p/articles/m.../ai_n28901382/

Regards all,

Cameron

[jonpry]

We should probably just agree to disagree. I don't see any use in pursuing this matter because it may be of no practical value. I think you argument doesn't really hold water though. This whole notion of chains of molecules needing to twist is fairly intuitive, but jut doesn't have anything to do with the way it really works. Epoxy curing is a thermodynamically favorable process. So at any temperature above absolute zero, it will cure, completely, eventually. If one were to make a new Tcg with a definition of the temperature that the epoxy will cure further, a useful amount, in a time period which I will live long enough to witness. I cannot prove that Tcg<Tg.

I agree that these properties are highly dependent on the curative used. I think there is a temperature, which is different for each agent, at which they kind of act the same though. Basically the breaking of the amine and joining it with the epoxide group has some hump energy. Below the temperature where the average molecule has enough energy to overcome this barrier, curing is quite slow, and since the stuff is a liquid, one could make the argument that Tcg>Tg. I think once you get beyond this activation energy the curing properties are similar. At the point curing starts to happen, there is a substantial loss of entropy in the system. Making the energy required to make the amine-epoxy bond much higher. It seems totally reasonably to me that one can never get a sufficient amount of entropy back into the polymer (to cure in a reasonable time) without making it go through the phase change.

[Steven.ji]

I heard a Spanish company engaging in polymer concrete, does anyone know the name of this company?

Steven

[johnohara]

Steven.ji~

Cosentino, S.A.

http://www.silestone.com/world/compania.htm

~John

[Steven.ji]

Steven.ji~

Cosentino, S.A.

http://www.silestone.com/world/compania.htm

~John

Dear Friend

This is stone for decoration, not for machine bed.

I heard a machine tool company cooperate with a university in Spanish. They already get this technology.

Is there anyone know about it?

BR

Steven

[brunog]

Steven,
I believe it's FATRONIK-Tecnalia : www.fatronik.com

Best regards

Bruno

[ckelloug]

Let me be the first to welcome Mr. Terry Capuano, author of the Machine Design article on E/G and president of Castanite (formerly of Accures Castings) to CNCZONE. For anyone who didn't notice, he just posted to the index thread for the E/G thread.

[cncagain]

Did anyone ask Terry any questions yet? He volunteered to answer. No posts for over a month, is this thread now sleeping? There are some interesting things over in the practical use thread for e/g. Aluminum oxide looks promising.
Has anyone made anything useful from this material yet?
Ken

[Herbertkabi]

Dear Friend
This is stone for decoration, not for machine bed.

Hmm?
http://www.cnczone.com/forums/showthread.php?t=85699,
At that many machines in cnczone made from wood :violin:

Cheers,
Herbert

[ckelloug]

Great Work, Herbert :cheers:

I exchanged an e-mail with Terry. I'd have to say that I felt like he was marketing but it's hard to tell over e-mail.

In our short exchange, he said this:

<blockquote>"Our PC has a resin content of only 7%. It is extremely important to keep the
resin content low to maintain properties ideal for machinery bases. Since we
describe the content in weight percent a small change in content has a big
change in properties."</blockquote>

Regards All,
Cameron

[jhudler]

In our short exchange, he said this:
"Our PC has a resin content of only 7%. It is extremely important to keep the resin content low to maintain properties ideal for machinery bases."

That pretty intuitive, and doesn't sound like anything we don't already know. If he's commercial would he be willing to send you (Cameron), samples to test? What about pricing?

-Jack

[johnohara]

If he's commercial would he be willing to send you (Cameron), samples to test? What about pricing?

Or his process/formula for success at 7%.

~John

[Herbertkabi]

I dont believe these thing are in US otherwise than in Europe - you can go and ask samples from nearest workshop represents ***stone company - they have huge lot of on the backyard. I got small samples before I ordered my parts and got large "samples" after received my order - they was not envious guys at all, largest plate was 600 x 1200, there was some insignificant color defectes and because called back by some high horse housewife.
cheers,
herbert

[ckelloug]

Somebody else ought to talk to Terry at www.Castinite.com. I've said enough about what I was up to that I'd be surprised if he tells me anymore. At any rate, though, the 7% by weight corresponds well to the 88% by volume.

Regards All,

Cameron

[johnohara]

Cameron~

Roach contributed more to this thread's discussion than Terry ever will. At least his posts were funny, interesting and informative.

Cider, xbox, bouncin' molds and insight.

$.02
~John

[ckelloug]

I miss Roach. I learned a lot decoding the things he was saying.

Say, Look what showed up today over at the lab This is a 2HP counter rotating vibrator vibrating table with vertical only vibration along with a TECO N3 3HP VFD. Should make martinis "shaken not stirred" as well as good E/G specimens. I've got to catch up with Herbertkabi since he's giving me grief over on his build thread

[johnohara]

Then there it shall be. Post 4000 is dedicated to Walter and Roach.

Here's a tip of the hat to you too Cameron as well as lgalla, greybeard, jhudler, brunog, martinw, Geof, Zumba, romihs, jsage, and the4thseal.

Happy 4000th post everybody.

~John

[vishnu]

I think its time to freeze this thread. No one on earth today will have time to read 334 pages & 4000 posts, but if one does he will earn a Doctorate . Its up to the cnczone moderators to decide. New baby threads on this area will be suitable i hope.