# These are flashcards an notes made by students on topics like 'droplets', 'particles' and 'droplet', originating from:

ISBN-13 9990002019708
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## Study Cards on droplets, particles, droplet

Which properties of an emulsion are quite dependent on size?
• Larger droplets cream/sediment easier due to gravity
• The appearance of a product
• Small droplets (<50 nm) --> almost transparent
• Larger droplets (50 nm - 10 um) --> scatter light (milky white)
• Even larger --> scatter light much less (yellowish)
What are 2 different ways of counting particles to obtain the distribution curve?
1. Count the number of particles smaller than a size --> particles that are much larger also count for 1
2. Total interfacial area present on the particles --> smaller droplets count less than larger droplets --> more realistic
3. Volume of the particles smaller than the specific size --> total amount of oil present in small, medium or larger droplets
Which 4 ways can be used to determine the average droplet size?
• By looking at the frequency distribution and taking the size at which the distribution is maximal --> modal size
• Summing up the size of all particles and dividing by number of particles --> number average diameter (d10)
• Sum up the volumes of all particles and divide this by the total number of particles --> volume average diameter (d30)
• Summing up the volume of the particles and dividing it by the surface are of the particles --> Sauter diameter (d32)
Which 3 things about droplets can be measured?
• Droplet size distribution
• Average droplet size
• Width/span of the distribution
What is the difference in stability of droplets with a different distribution width?
Monodisperse (same sized droplets) --> more stable
Polydisperse (smaller and larger) --> less stable, larger droplets can initiate creaming
What are 4 different methods to measure the droplet size distribution?
1. Microscopy
1. Droplets larger than 1 um --> optical microscopy
2. Droplets smaller than 1 um --> electron microscopy
2. Light scattering
3. Following the dynamics of the droplets (dynamic light scattering) --> Doppler shift, larger droplets slower Brownian motion
4. Count droplets individually --> Coulter counter method