These are flashcards an notes made by students on topics like 'coating', 'melt-based' and 'crystallisation', originating from:

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- Wageningen University
ISBN-13 9990002019708
665 Flashcards & Notes
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Study Cards on coating, melt-based, crystallisation

For which materials is melt-based formation mechanism suitable?
For materials that can form melt at attainable temperatures.
What happens during melt-based formation mechanism?
The product is dipped in a bath of the melt (e.g. Chocolate coatings).
Which 2 mechanisms in melt-based formation mechanism can lead to the formation of a coating?
  1. If the product itself is below the crystallisation or solidification temperature, the melt will solidify against the product. If this is caused by crystallisation, this will lead to a solidified layer around the product.
  2. The melt does not solidify during dipping; a layer of liquid material sticks to the surface of the product. The time of immersion is not important. The product should be transferred as quickly as possible to a cooler (e.g. Blast cooler), where the film is solidified.
How are the coating thickness and keeping time in the cooler related?
A coating that is 2x as thick, needs a cooling time that is 4x as long.
What can be reasons that the coating is inhomogeneous due to film drainage?
If the coating solution does:
  • Not have a sufficiently high viscosity
  • Have another barrier against flow
What can prevent material to have film drainage?
  • Rotating the product
  • Adding components, such as polymers to the solution
  • Properties of the film can be altered by tempering. This can lead to re-crystallisation, giving other crystal shapes or different orientation in the film. It can also lead to a reduction in the amount of defects and to a change in mechanical properties.
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