IUPAC > Gold Book > alphabetical index > D > degree of crystallinity of a polymer


degree of crystallinity

of a polymer
The fractional amount of crystallinity in the polymer sample (w c for mass fraction; φ c for volume fraction).
  1. The assumption is made that the sample can be subdivided into a crystalline phase and an amorphous phase (the so-called two-phase model).
  2. Both phases are assumed to have properties identical with those of their ideal states, with no influence of interfaces.
  3. The degree of crystallinity may be expressed either as the mass fraction or as the volume fraction, the two quantities being related by w c = φ c ρ c ρ where ρ and ρ c are the densities of the entire sample and of the crystalline fraction, respectively.
  4. The degree of crystallinity can be determined by several experimental techniques; among the most commonly used are: (i) X-ray diffraction, (ii) calorimetry, (iii) density measurements, and (iv) infrared spectroscopy (IR). Imperfections in crystals are not easily distinguished from the amorphous phase. Also, the various techniques may be affected to different extents by imperfections and interfacial effects. Hence, some disagreement among the results of quantitative measurements of crystallinity by different methods is frequently encountered.
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Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.
Last update: 2014-02-24; version: 2.3.3.
DOI of this term: doi:10.1351/goldbook.D01565.
Original PDF version: http://www.iupac.org/goldbook/D01565.pdf. The PDF version is out of date and is provided for reference purposes only. For some entries, the PDF version may be unavailable.
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