I have synthesised Sty-BA latex with %40 SC but I would like to increase viscosity? Particle size is nearly 100 nm. Does it depent on PS? What can I do to increase viscosity?
Hello dear, I dont know which is your case, but you can do it so;
1) Increasing the solid content
2) Increasing the particle size (it can be obtained, reducing the surfactant amount employed in the synthesis).
3) add an tickener
In addition to the options pointed out by Dr. Murillo, you can achieve increased viscosity by promoting latex crosslinking.
we increase viscosity of latex as NBR or SBR latex by very low irradiation dose. It may be gamma or electron beam as physical methods
And also I use APS initiator, SDS and non-ionic surfactant mixture. Sty-BA ratio is 50/50.
Dear Ali,
Have you tried to increase the "Degree of Polymerisation of individual polymer components"?
The smaller is the distance between the particles, the higher is the interaction between them. The higher is the interaction between the particles, the greater is the viscosity of the latex.
There are two ways to increase the viscosity of a latex. INCREASING the solids content or DECREASING the particle size.
For example, if you have a particle size as small as 20 nm you can not have a solids content greater than 20 or 30% because you will have practically a gel.
However, you have to consider that very small particles tend to be more unstable and may coalesce to form larger particles or clots.
You can also add thickeners to the latex but you have to check the compatibility with the rest of the formulation to avoid the colloidal instability of the latex.
Finally, the polymer is within the particles so its molecular weight does not influence the viscosity of the latex.
Dear Esther
Your answer and Murillo's answer contradict with each other about particle size. ???
I support Dr.Murillos suggestions.But keep in mind increasing particle size may lead to unstable latex.So may be a combination of all the approaches,in consideration of the properties required is to be used.
If the particle size is increased at the same solids content, the viscosity of the latex will decrease.
Dear Ali
You have two parameters to consider: solids content and particle size.
Keeping constant the solids content , to decrease the distance between particles you have to reduce their size. You can do the calculation.
Keeping constant the particle size, to decrease the distance between particles you have to increase the solids content. You can also do the calculation.
When particles are closer each other, there are more interactions among them and the viscosity of the latex is higher.
You can find a better explanation in chapter 13 of the book of P.A. Lovell & M.S. El-Aasser: Emulsion Polymerization and Emulsion Polymers.
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