14206 IUPAC Gold Book - axial advancement per constitutional repeating unit 10.1351/goldbook.14206 14206 current synonym: unit height 1 Projected length of a constitutional repeating unit (CRU) on the chain axis. The axial advancement per CRU is characteristic of the conformation of a polymer chain. A large axial advancement per CRU is said to define a more extended conformation and a small axial advancement per CRU is said to define a more contracted conformation. The value of \(h\) is obtained from the equation \[h = \frac{c}{M_{\rm{R}}}\] where \(c\) is the chain identity period and \(M_{\rm{R}}\) is the number of CRUs in \(c\). In cases where the equivalence postulate does not apply, \(h\) is an average value. PAC, 2011, 83, 1831. 'Definitions of terms relating to crystalline polymers (IUPAC Recommendations 2011)' on page 1836 (https://doi.org/10.1351/PAC-REC-10-11-13) https://goldbook.iupac.org/terms/view/14206/html https://goldbook.iupac.org/terms/view/14206/json https://goldbook.iupac.org/terms/view/14206/plain Citation: 'axial advancement per constitutional repeating unit' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.14206 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. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . 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. 2026-06-29T00:19:37+00:00