{"term":{"id":"12813","title":"time–temperature superposition principle","longtitle":"IUPAC Gold Book - time–temperature superposition principle","doi":"10.1351\/goldbook.12813","code":"12813","status":"current","synonym":"<em>synonym<\/em>: TTS Principle","definitions":[{"id":1,"text":"Principle stating that the value of a viscoelastic property measured at a given temperature, after a given length of time or at a given frequency, is equal to the value of the property at a different temperature after a length of time or at a frequency equal to the given length of time or given frequency multiplied by a shift factor, \\(a_{T}\\) , with the value of the shift factor being independent of length of the time or frequency.","notes":{"1":"The Williams–Landel–Ferry (WLF) equation provides a semi-empirical relation between the shift factor \\(a_{T}\\) and the temperature, at temperatures near the glass-transition temperature, \\(T_{\\rm{g}}\\)."},"links":[{"term":"Williams–Landel–Ferry (WLF) equation","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/12821"},{"term":"shift factor","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/12801"}],"sources":["PAC, 2013, 85, 1017. 'Glossary of terms relating to thermal and thermomechanical properties of polymers (IUPAC Recommendations 2013)' on page 1042 (https:\/\/doi.org\/10.1351\/PAC-REC-12-03-02)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/12813\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/12813\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/12813\/plain"},"citation":"Citation: 'time–temperature superposition principle' 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.12813","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.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","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.","accessed":"2026-04-18T01:26:05+00:00"}}