Bisphenol A Epoxy Resins - Session 17 

For that case, you should choose the right set of Epoxy - Hardener system. search for top-coating products, which are resistant to yellowing. Be aware that if your epoxy is suitable, you should go for a proper hardener also. For example TETA and DETA or their adducts could be good choices. Check the TDS of the employed Epoxy and Hardener, make sure that their color is below 100 APHA. Moreover, the hardener is so susceptible to moisture and oxygen. they should be avoided...

Hello, thanks for your comment. You react ECH with Bis-A? or you add NaOH solution to the prepared epoxy-hardener solution? Explain your procedure and I will look through it.

If you want to react ECH with Bis-A to produce epoxy resin, you should be aware that the presence of NaOH may alter the reaction. One of the reactions of epichlorohydrin is hydrolysis with sodium hydroxide. This reaction produces glycerol and sodium chloride as the main products. The hydrolysis of epichlorohydrin is a step-growth polymerization that can produce linear or crosslinked polymers depending on the concentration of sodium hydroxide, the reaction temperature, and the dropping method . The lower the concentration of sodium hydroxide, the higher the yield of glycerol...

@@EpoxyChannel-yu9bu yes I am producing liquid epoxy resin based on bisphenol A and epichlorohydrin with NaOH as a catalyst. The application of this epoxy resin would be used in the coating field. The change of colour turns to yellow apear after adding the NaOH as a catalyst. Could you please give some advice to solve this problem

Hey Jaffar. Thanks for your explanation. Actually, there are crystal clear epoxy products on the market for the intended use... but if you want to synthesis the resin yourself, you should be aware of a few points. Firstly, the role of NaOH is to close the opened epoxy at the latest stages of the reaction, and as the reaction is thermodynamic equi, this kind of yellowing is investible. Even ordinary epoxy products at the market are kind of yellow. The premium products are crystal clear and have higher prices in the market. Moreover, be aware that the color often has little effect on the properties of the final product. If you wish to have a crystal clear product, First, you have to use super pure ECH and Bisphenol A and NaOH at the first step. Secondly, the whole reaction, even step 2, MUST be conducted under an inert gas blanket, say under nitrogen or argon gas. You should avoid oxygen, CO2, and humidity during the synthesis and avoid higher temperatures. Briefly, you should minimize oxidation. Metals can also result in yellow color in your product. The contact with metals, i.e., pipes, should be minimized. Finally, in the industry final product is often purified and color will be omitted. Distillation of the final product, again under nitrogen purge is another strategy you can count on... @@jafarrullahabdulaziz18

please communicate through my email and I see what is the situation you are exactly refereeing to. For now, be aware that there is a conflict between the type of hardener and the employed chemical, if you have used proper system.

@@EpoxyChannel-yu9bu please may you write your email address sir

@@EpoxyChannel-yu9bu please if you don't mind to write your email sir

@@EpoxyChannel-yu9bu please may you write your email address the we can discuss sir