In regards to ambient air moisture absorption, will increasing hydrophobicity also limit the hygroscopicity of nylon 6,6? My thoughts are that by limiting the surface interactions of moisture, you can also limit the bulk absorption of the moisture. As in, maintaining the same level of hygroscopicity but reducing the rate of ambient moisture absorption by increasing hydrophobicity.
Thanks in advance.
Hey Thomas,
I'm no expert, but I think Nylon 6,6 is hygroscopic as a result of the amide having a large electrostatic attraction to water resulting in hydrogen bonding. With that logic, you would have to remove the amide functionality or give it a better hydrogen bonding agent than water to prevent it from wanting to absorb the water. Unfortunately, removing the amide = loss of precious properties... I wonder if protecting the amide N-H could help prevent some of the hydrogen bonding? although it would probably mess up the properties as well.. Surface chemistry could possibly work, you could do a test run where you soak the fibers in some sort of amphiphile that has a preference for amides, won't be permanent but would at least test your theory...
That or store it in a desiccator and heat before using. . . :/
Hope this helps.
Baillie
Dear all,
as far as the surface is the starting point for water absorption and diffusion to the bulk matrix, I suggest two idees:
- surface crosslinking (by radiation for exemple).
- surface grafting of hydrophobic compound (water repelant).
Regards
make the amide positive and add carboxylate should from a poly electrolyte complex
Thanks for the feedback! I have experience with surface treatment for wettability in polypropylene and polyethylene fabrics, but it's a bit tricky trying to alter the polymer itself before spinning the fibers. I'll definitely look into these suggestions and hopefully be able to provide an update in the future.
@Bailie, you're right on that! I can't sacrifice any of those precious nylon properties though since we still have to maintain spec for our products.
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