Hello,
I'm looking for an easy way to detect if a PET film is AlOx/Siox coated or not.
especialy when PET is laminated to another film (e.g. PE).
Thanks for your help.
What surface equipment do you have access to? XPS should be able to tell you.
What surface equipment do you have access to? XPS should be able to tell you.
If you have access to XPS or IR spectrometer the suggestions of Joseph and Andrei are the way to go. If you don't have or you are looking for a quick-and-dirty test: water contact angel.
Put a drop of water on the film. The CA will be 80-90° in the case of PET, around 100° for PE. If you have an oxide coating (no matter if it is SiOx, AlOx, or others) a water drop will have a CA in the range between 40° and about 70°. This is due to adsorbates from the atmosphere. Water will spread (CA < 10°) on a clean oxide surface. You can clean the coating by a thorough flushing with e.g. isopropanol, pure (non-denaturated!) ethanol, aceton. Use a solvent with a low content on non-volatile substances and let it run off the surface rather than letting dry the liquid film.
Thank you all,
XPS can't always work because in some cases AlOx is also coated with a protective layer. So I'm interested in FTIR (ATR or transmission) if I can monitor a specific wavelength?
Regards.
If the XPS has the capability to do sputter depth profiling, then that should work no matter what other coatings. I am not sure IR will do what you want now that you say there are other coatings, but it would certainly be the easiest to try.
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