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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: pmg on December 06, 2011, 04:04:20 AM

Title: Viscosity and blending
Post by: pmg on December 06, 2011, 04:04:20 AM

Is it possible to work out the viscosity of two liquids when mixed at room temperature using a formula?

I have an ISO 220 and an ISO 15.

Is there a formula that will give the volumes of each one that is required to create an ISO 68 in any amount. Or a formula that can be adapted to reach any viscosity just by mixing two viscosity's? Or a formula that would need them to be heated to different temperatures???

Thanks

Title: Re: Viscosity and blending
Post by: fledarmus on December 06, 2011, 07:37:06 AM

not really - viscosity is so dependent on the exact nature of the intermolecular interactions that there really isn't a good theoretical model for determining viscosities of mixtures.

That being said, there are particular types of mixtures for which calculations have been developed. I have seen methods for calculating the viscosity of mixtures of polymers which have the same structure but different average molecular weights, and empirical methods for calculating viscosities of oils blended from proprietary formulations (essentially a graph of composition vs. viscosity from blending a high and low viscosity oil). These are mixtures of very similar compounds differing only in molecular weight, so the intermolecular interactions are as similar as possible.

I don't know what your particular application is, but if you contact the providers of your materials, they may know the viscosity dependence on mixing.

Title: Re: Viscosity and blending
Post by: marquis on December 06, 2011, 10:33:57 AM

Many times, it depends on if the liquids are newtonian or non-newtonian.  If they are newtonian, you have a chance.  Unfortunately, most liquids are not newtonian.

Good luck.