“Did you know…….?.” series for May/June 2019
"Did you know that different instruments used for particle size measurements operate on different principles, and often give different average particle diameters and particle size distributions? Key questions for latex producers are therefore: What is the best type of instrument? What particle size measurement method is most useful for my purpose (quality control, scaleup, R&D)? Which average particle diameter should I be using in my work (number average? volume aveage? intensity average)? The answers to these questions can have important implications for ensuring consistent latex quality or for successfully troubleshooting scaleup and production problems. For example, DLS (dynamic light scattering) is perhaps the most commonly used technique. However what is often not realized is that DLS is not very sensitive to the presence of small particles if larger particles are present. You could have a significant population of small particles made by secondary nucleation, which may dramatically impact your latex properties, and yet your particle size measurements may not reveal anything unusual. More generally, particle size measurements from different instruments cannot be reliably compared to each other.
This subject is treated in detail in several of our STEPn workshops, especially STEP 2 “Characterization of Latex Particles”.
We welcome comments and further discussion of this topic. Please contact us via our website. epced.com