https://doi.org/10.1351/goldbook.D01565
The fractional amount of for for
crystallinity
in the polymer sample (mass fraction
; volume fraction
).Notes:
- The assumption is made that the sample can be subdivided into a crystalline phase and an amorphous phase (the so-called two-phase model).
- Both phases are assumed to have properties identical with those of their ideal states, with no influence of interfaces.
- The degree of crystallinitymay be expressed either as themass fractionor as thevolume fraction, the two quantities being related by
where and are the densities of the entire sample and of the crystalline fraction, respectively. - The degree of crystallinitycan be determined by several experimental techniques; among the most commonly used are: (i) X-raydiffraction, (ii)calorimetry, (iii) density measurements, and (iv)infraredspectroscopy(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 ofcrystallinityby different methods is frequently encountered.