Title: glass
Long Title: IUPAC Gold Book - glass
DOI: 10.1351/goldbook.12773
Status: current

Definition
Amorphous matter in the glassy state, i.e., below its glass-transition temperature.

Notes
1) A glass is usually described as a solid, as most physical properties vary in a manner similar to those in the crystalline state. However, considering the ongoing debate about the nature of the glass transition, and the ability of some glasses to flow, some authors prefer to consider glasses in the context of the liquid state.
2) The creep compliance of a glass is less than \(\pu{E-9 N-1 m2}\), and the dynamic viscosity larger than \(\pu{E4 Pa s}\).

Related Terms
- crystalline state: https://goldbook.iupac.org//terms/view/12754
- glassy state: https://goldbook.iupac.org//terms/view/12774

Source
- PAC, 2013, 85, 1017. 'Glossary of terms relating to thermal and thermomechanical properties of polymers (IUPAC Recommendations 2013)' on page 1029 (https://doi.org/10.1351/PAC-REC-12-03-02)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/12773/html
- json: https://goldbook.iupac.org/terms/view/12773/json
- xml: https://goldbook.iupac.org/terms/view/12773/xml

Citation: Citation: 'glass' 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.12773
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Accessed: 2026-04-18T06:00:24+00:00