There are arguments in support of both. As far as I know, determining the percent crystallinity with XRD only requires one sample, while with DSC you would need a reference sample with which to compare your experimentally determined values. DSC would probably be the quicker method though, if time is a constraint. You also have to be sure you have accurate temperature and enthalpy calibrations as well as an accurate determination of the peak areas. If you have easy access to both methods, why not try both and compare your results? Hope this helps.
Really good question, I would agree with Zach Evenson. However how the material is presented would be an issue. For powders DSC would be better, because preferred orientation effects in XRD come into play if the crystalline regions or particles are in the nm region. Have you considered dynamic mechanical analysis? This would be much better for monitoring crystallinity and or amorphous content if you have a monolith. I have published a little (2 papers) on using DMA with a powder pocket for amorphous pharmaceuticals and pharmaceutical polymers. But the best approach would be to investigate any review paper or book by Bernard Wunderlich, he is one of the word leaders in the analysis of polymers using thermal techniques. Cheers Paul
As has been suggested by Zach Evenson, why not try both method and compare the result. However it should be noted out that both techniques are temperature dependence. While running the DSC for polymer needs higher temperature than that of XRD, one should wonder what kind of comparison we would have. Whats more if the running temperature is somewhere near a trasformation region,one would expect the degree of crystallinity is slightly higher.
May be DSC is a faster and much more straight forward to get the crystallinity, provided that you have the enthalpy value for a 100% crystalline material (which is generally theoretically calculated). I am not sure if either of the methods can be designated 'more accurate', you probably need to decide on availability, convenience etc. As point out by others, it could be interesting to compare the values from these methods, not sure if the comparison is reported already for any system.
Well i Guess that his will depend on the sample itself. As long as in both cases the method is based on calculating areas the accuracy on the method will depend of how much clear are those areas.
Other question might be how the different spherulite size or different allomorphic phase could influence the measure in that cases ...
I guess that, We cannot compared the result obtained by Both method quantitatively but can qualitatively.
In order to compare these two techniques one should note that newly developed X-ray sources and detectors provide a very good spatial resolution. "it is possible to follow development of structure in a processing line, such as in spinning and drawing operation, or in extrusion of films with a time resolution of less than one second." [1] Another example would be studying structural inhomogenities caused by temperature or stress gradients during the process. Please note that these are only developments with the conventional "two-phase" model. There are also a set of new methods that such as Grazing Incidence Diffraction (for studying thin films) or Microbeam diffraction that can be used in special cases to gain even better results. So from my standpoint, XRD is the number one technique for polymers and gives more reliable results. However, like all other methods, it has its own drawbacks. The one that comes to my mind is that when degree of crystallinity is very low, the peaks are very weak and hard to distinguish from fully amorphous polymer.
DSC or in general Thermal Analysis are complementary methods to further investigate the sample and you can obtain different parameters such as enthalpy of crystallization from it. It is suggested, as it is written in previous comments, that if possible, combination of these techniques be used to get more accurate results.
[1]https://www.researchgate.net/publication/230561647_Recent_developments_in_polymer_characterization_using_X-ray_diffraction
I also ask you to take a look at this papers:
http://onlinelibrary.wiley.com/doi/10.1002/polb.10128/abstract
Article Recent developments in polymer characterization using X-ray ...
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