I want to calculate the PDI for droplets in the emulsion but I found two equations for this as follows:
PDI=Mw/Mn
PDI=(Standard deviation)/(Average mean size)
I calculate PDI for the prepared emulsion with this two formula, but they give two different answers.
What is the relation between these two equations?
They are different equations for Pdi and both are correct. One relates to MW polydispersity (usually in polymers) and the other to particle size distribution. There is no relationship between them. All emulsions are thermodynamically unstable.
There is no 'correct' range. I think you are still confused with your first PDI that refers usually to polymeric systems. In terms of emulsion particle size distribution, a wide distribution may imply that the particles are agglomerating or creaming but this is not a given. Your question is akin to 'how long is a piece of string'?
I found the answer and you tell wrong.
The PDI value of approximately 0.1 is correspond to the polydispersity of monodisperse standards and values greater than 0.7 indicate that the sample has a very broad size distribution.
Please download the attached file.
@Hossein Esmaeili
What has your last comment to do with the question you asked and what is the relation between polydispersity of a monodisperse standard and an emulsion? Your thought process is extremely confused. Incidentally a polydispersity of 0.1 does not correspond to a monodisperse particle size standard. These typically have lower Pdi's (
I think there are no differences between them. The PDI has a specified definition
@Hossein, Alan Rawle is right. Those two PDIs you mention in your question are two different things.
In fact, PDI=Mw/Mn is a quantity used to describe the polydispersity of Polymers. Polymers and Emulsions are also two different things. How would you define Mw and Mn of an Emulsion?
I recommend reading a good book on colloidal science (e.g. The Colloidal Domain) to get a good foundation of the science before trying to dig information from papers, which often are concerned with more specific aspects.
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