Powder XRD will recognize crystalline and polycrystalline regions if you are able to spin the sample 360 degrees whilst taking the 2-theta scan. It will also, in a sense, recognize amorphous regions in that there will be only a large broad region with no distinct peaks. For clarification, it sounds as though you are looking to distinguish between two highly ordered states that are of different sizes? How do you believe the states are different from each other if it is not size? If you ARE looking to distinguish by size you can use the Scherrer equation to get the coherent crystal domain size from the full-width half-maximum of the crystal peaks present in the XRD scan.

Thanks Susan, However, I am not looking for differences based on the size of the cellulose crystals but the samples differ in having or not the crystalline domains ( For simplicity sake, I am leaving out the amorphous regions for the moment). The ordered state does not necessarily have the same inter chain-distance as in the crystal form. Moreover, the ordered state is smaller in size (in the cross-direction of the chain) compared to the crystal cross-section. Further two or more ordered units may align with each other in a way that causes some imperfection, from a crystal point of view, on the interface.

One more thing, just to clarify. The two samples, one ordered and the other crystalline, are not mixed together. They will be analyzed separately. Can I then expect to see different characteristics in the diffractograms?

Three simple comments:

- cellulose is one of the examples often used by ICDD to see how it is possible to identify it and say something about crystallinity (see e.g. http://www.icdd.com/knowledge/tutorials/pdf/How%20to%20analyze%20polymers.pdf)

- PDF analysis can tell you a lot in this case (you need a very large Q range to be able to tell something about hte local and the average structure)

- if you ARE looking to check for size, please READ before using Scherrer equation (there are lot of comments about this in several other threads). Scherrer equation was developed in a very specific case (seldom met) and extending it arbitrarily in scope and meaning is in several cases nonsense. I can't even imagine the meaning of that equation for a macromolecular system. For a material like this, a paracrystal model is perhaps more adequate and something about modelling the microstructure of paracrystals is available in the literature

Thank you Matteo for the useful link.