[Dolphinsiu]

I do think that eveyone knows what epoxy resins is if we have done experiment in science club. However, do anyone know what exactly epoxy resins are made of? Someone says it is made from unsaturated polyester, hardening agent (purple liquid, actually I don't know what exactly the chemical compound is used) and enhancer (cobalt salt. Again I don't know what salt exactly is used). The product formed is highly transparent. Do anyone has information available for epoxy resin? (As I really feel confused why it is usually shown to be made of epichlorohydrin and bisphenol-A, is such polymer formed by free radical polymerization or condensation polymerization?). Thank you!

[ARGOS++]

Dear Dolphinsiu;
One of the most important representatives is Araldite!
I wrote already once about in the Forum.

A Lot of Info you can get at:  "What is Araldite?”.
Also Wiki knows little bit about:  "Araldite”.
(see there under: “Epoxy”.)

I hope to have been of help to you.

Good Luck!
                    ARGOS⁺⁺

[Dolphinsiu]

But do you know the purpose of adding hardening agent and enhancer (cobalt soap)?

[Arkcon]

All I have is the following Wiley journal link with abstract, but at least it gives you a starting point for your literature search:

http://www3.interscience.wiley.com/cgi-bin/abstract/104027836/ABSTRACT?CRETRY=1&SRETRY=0

[ARGOS++]

Dear Dolphinsiu;

The Resin reaction needs on one side to be catalysed, and on the other side there most be a “partner” for Chlorine.

I don’t know the exact mechanism but you may try to balance the reaction.
If I’m not completely wrong, then on the right side HCl must result as one product (maybe bound to the hardener), because during hardening it does never smell like Chlorine, but like an “Amine”.

Maybe Cobalt soap is what they tell, an enhancer to design the wide variety of the resin property.

Good Luck!
                    ARGOS⁺⁺

[Dolphinsiu]

It seems I name the word wrongly. It should be polyester resin. It is a transparent plastic in liquid state. After casting and drying, it will form different shape of cubic according to the shape of the cast.

References:
http://ccn.hkcampus.net/~ccn-t01/resin.ppt

I hope you can understand what I have said according to the picture from the powerpoint in the above slide.

From Arkcon,
 
The effects of adding various cobalt complexes to a tetraglycidyl methylene dianiline-based epoxy resin were determined. The addition of cobalt(III) acetylacetonate was found to alter the epoxy cure and improve the flexural strength and fracture toughness of the cured resin. These effects were not duplicated by the addition of various other cobalt complexes...

[Arkcon]

From Arkcon,
 
The effects of adding various cobalt complexes to a tetraglycidyl methylene dianiline-based epoxy resin were determined. The addition of cobalt(III) acetylacetonate was found to alter the epoxy cure and improve the flexural strength and fracture toughness of the cured resin. These effects were not duplicated by the addition of various other cobalt complexes...

Oh yeah, that's what the abstract says, but you'll need the article to really understand it.  I also found a patent while Googling, so you can look into that, if you're really interested.

[Dolphinsiu]

Actually do anyone know the actual monomer and initiator used in make this craft?

http://home.cpss.edu.hk/eca/sci_soc/expt/PS.htm