long period

symbol: $L$; unit: $\pu{m}$
synonym: long spacing
https://doi.org/10.1351/goldbook.14251
Average periodicity (repeating distance) of the layers of lamellar crystals in a stacked assembly.
Note: The long period is usually measured by SAXS (small-angle X-ray scattering), SANS (small-angle neutron scattering), atomic force microscopy (AFM), or transmission electron microscopy (TEM), and is the sum of the average thickness of the lamellar crystals and the average thickness of the amorphous inter-lamellar region.
Source:
PAC, 2011, 83, 1831. (Definitions of terms relating to crystalline polymers (IUPAC Recommendations 2011)) on page 1855 [Terms] [Paper]
Citation: 'long period' 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.14251 RIS BibTex EndNote
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