Term: degree of crystallinity
https://doi.org/10.1351/goldbook.D01565

Definition:
The fractional amount of crystallinity in the polymer sample (w c for mass fraction; φ c for volume fraction).

Notes:
0) The assumption is made that the sample can be subdivided into a crystalline phase and an amorphous phase (the so-called two-phase model).
1) Both phases are assumed to have properties identical with those of their ideal states, with no influence of interfaces.
2) The degree of @C01433@ may be expressed either as the @M03722@ or as the @V06643@, the two quantities being related by wc = φc.ρc/ρ where ρ and ρ c are the densities of the entire sample and of the crystalline fraction, respectively.
3) The degree of @C01433@ can be determined by several experimental techniques; among the most commonly used are: (i) X-ray @D01711@, (ii) @C00786@, (iii) density measurements, and (iv) @IT07399@ @S05848@ (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 @C01433@ by different methods is frequently encountered.

Related Terms:
1) crystallinity (http://doi.org/10.1351/goldbook.C01433).
2) mass fraction (http://doi.org/10.1351/goldbook.M03722).
3) volume fraction (http://doi.org/10.1351/goldbook.V06643).
4) diffraction (http://doi.org/10.1351/goldbook.D01711).
5) calorimetry (http://doi.org/10.1351/goldbook.C00786).
6) infrared (http://doi.org/10.1351/goldbook.IT07399).
7) spectroscopy (http://doi.org/10.1351/goldbook.S05848).

Source: Purple Book, 1st ed., p. 75 (http://old.iupac.org/publications/books/author/metanomski.html)

Citation: 'degree of crystallinity' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.D01565

License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.

Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.