degree of crystallinity

of a polymer
https://doi.org/10.1351/goldbook.D01565
The fractional amount of
crystallinity
in the polymer sample (wc for
mass fraction
; ψc for
volume fraction
).
Notes:
  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 wc=ψcρcρ where ρ and ρc 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.
Source:
Purple Book, 1st ed., p. 75 [Terms] [Book]