[HailoMan]

Apology in advanced if this is a silly question, but is melamine hygroscopic?
Looking at the chemical structure, one would almost immediately assume that it is hygroscopic: http://en.wikipedia.org/wiki/Melamine

However, I tried looking it up and the following data sheet from a supplier claims that it is non-hygroscopic:
http://www.at-ir.com/melamine/DataSheet/==TechnicaLInformation==DMM2006TISGPH.pdf
However, they do mention that "Depending on ... moisture content and storage conditions, occasionally lump formation may occur". Does that not imply that it is somewhat hygroscopic (otherwise why would moisture content affects lump formation?!?!). Water solubility of 3 g/L is also not all that low.

[discodermolide]

I am not sure you can infer hydroscopicity from the molecular structure.
Anyway is there a definition of this property? I mean in terms of how much water a compound absorbs in a given time at a certain temperature and humidity?

[HailoMan]

Well, I was simply inferring it based on the multiple amine groups on melamine (generally speaking makes a molecule more hydrophilic?)

As for the definition of this "hygroscopy"?
I'm mainly interested in knowing if under ambient condition melamine is likely to soak up water (say if 1% of its weight would be made out of water if left standing under ambient condition).
Just hoping for rough indications that's all.

[discodermolide]

Well do the experiment and see what happens.

[HailoMan]

Well do the experiment and see what happens.

Just in planning stage at the moment, hence why I posted here.
Don't wanna order 1 kg of melamine just to find out that it soaks up water.

[discodermolide]

In your link to the technical info. it says "It is a stable non-hygroscopic chemical when stored under normal, dry warehouse storage conditions.".
Unless you are in a high humidity environment I would expect that statement to be correct.