I am producing a flocculent precipitate when doing free radical polymerization of itaconic acid in aqueous solution, what should this substance be? How is it produced?The initiator is sodium persulfate at five percent of the total reactants, and the reaction temperature is 80 ℃.
Article Free-radical polymerization of itaconic acid in the presence...
Dear all, most probably it is an insolubility as a consequence of crosslinking. If so use the neutralized salt form of IA. Please have a look at the attached thesis. By the way it not important to suspect the implication of the type of the initiator, it a matter of functional group and the high reactivity of IA (generally about 1hr is enough to achieve high conversion and high MW). My Regards
Abdelkader BOUAZIZ Thanks for your answer. I tried vacuum drying polyacrylic acid after synthesis, and I got film formation, is it because the MW of polymerization is too large? If I want to synthesize polyacrylic acid with a molecular weight of around 5000, what is the general reaction time and temperature?
I don't think 5000 MW is a polymer, may be it is a true oligomer. You should search and find kinetics studies on MW evolution with respect to polymerization time. These are old studies. My Regards
Your initiator most likely chemically reacts with your reactants and generates a stable molecules which might precipitate
There are many articles on the net where PAA is manufactured using APS and SBS as the initiators (The SBS controls the Mwt). You can even leave out the SBS and use small amounts of APS (0.2%). Add it over 3 - 4 hours. Check your Mwt thereafter and adjust the APS as required.
I never seen a precipitation of persulfates or SBS. This is very unusual in acrylic emulsion polymerizations. A polymer you are making is not dispersed well in your system and, as a result of that, it precipitated. I would recommend to try some other surfactants
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