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Short answer
Differential scanning calorimetry (DSC) is a thermal analysis technique that follows how a material’s heat behaviour changes as temperature is programmed. In practice it is used to read a glass transition, a melting temperature or a crystallization temperature, and each of those has its own ASTM test method with its own scope and operating range.
Definition and scope
DSC belongs to the family of thermal analysis methods. ASTM E794 describes it alongside differential thermal analysis (DTA) as a route to melting and crystallization temperatures, and ASTM E1356 uses DSC to assign glass transition temperatures. Both name research, quality control and specification acceptance as uses, so the method is used in research, quality control and specification acceptance alike.
DSC is about thermal events and heat capacity. It does not measure mass change; for that, see the guide on thermogravimetric analysis (TGA). The underlying physics sits in thermodynamics and, for the materials side, physical chemistry.
How DSC is used in practice
The two ASTM methods below show what a DSC result is actually asked to deliver.
Glass transition (ASTM E1356)
ASTM E1356, Standard Test Method for Assignment of the Glass Transition Temperatures by Differential Scanning Calorimetry, applies to amorphous materials and to partially crystalline materials that contain amorphous regions. The material must be stable, meaning it does not decompose or sublime in the transition region. DSC detects the glass transition because it appears as a step change in specific heat capacity, not as a sharp peak. The standard gives a normal operating range of -120 C to 500 C, which an instrument may extend. The glass transition temperature can reflect thermal history, processing conditions, stability and reaction progress (for the materials context, see polymer science).
Melting and crystallization (ASTM E794)
ASTM E794, Standard Test Method for Melting And Crystallization Temperatures By Thermal Analysis, covers the melting and crystallization temperatures of pure materials by DSC and DTA. It suits thermally stable materials with well-defined melting temperatures. The normal range is -120 C to 600 C for DSC and 25 C to 1500 C for DTA. Melting and crystallization appear as peaks, in contrast to the step of a glass transition.
Which standard covers which measurement
| Question | Method | Normal range | Fits when |
|---|---|---|---|
| Where is the glass transition? | ASTM E1356 | -120 C to 500 C | Amorphous, or partly crystalline with amorphous regions; no decomposition or sublimation in the transition region |
| At what temperature does a pure material melt or crystallize? | ASTM E794 | -120 C to 600 C (DSC); 25 C to 1500 C (DTA) | Pure, thermally stable material with a well-defined melting temperature |
The comparison above is the practical gain: the choice of method follows the event you need to locate, and the applicability condition, not the instrument, decides whether a result is valid. Current editions: ASTM lists E1356-25 as active for glass transition, and E794-24 as active for melting and crystallization, with the 2018 revision of E794 now historical (ASTM listings checked 2026-10-29).
Where it matters for labs and quality control
- Material that decomposes while it changes state. E1356 requires stability through the transition region, so a sample that decomposes or sublimes there is outside its scope. TGA is the mass-change measurement that addresses that question. Freeze-drying work is a related use of thermal data; see the lyophilization guide.
- Mixtures and impure materials. E794 is framed for pure materials; the standard covers pure materials, so a mixture falls outside its stated scope.
- Specification acceptance. Because both methods name specification acceptance as a use, the method designation and edition belong in the report next to the temperature.
Common misunderstandings
- “A glass transition is a melting point.” It is not. It is a step in heat capacity in amorphous regions, while melting is a peak.
- “DSC works for any sample.” Each method states the material types it suits; outside that scope the number is not covered by the standard.
- “DSC tells you what is lost on heating.” Mass loss is a thermogravimetric measurement. DSC and TGA answer different questions and are often read together.
- “One temperature range fits all.” The normal ranges differ between methods (-120 C to 500 C for E1356, -120 C to 600 C for DSC under E794), and instruments may extend them.
FAQ
What does differential scanning calorimetry measure?
It is used to locate thermal events such as the glass transition (a heat-capacity step), melting and crystallization (peaks) in a temperature-programmed run.
Which standard covers the glass transition by DSC?
ASTM E1356.
Which standard covers melting and crystallization temperatures?
ASTM E794, which covers DSC and DTA for pure, thermally stable materials.
How is DSC different from TGA?
DSC reports thermal events and heat capacity changes; TGA reports mass change with temperature.
Sources
- ASTM International, E1356 Standard Test Method for Assignment of the Glass Transition Temperatures by Differential Scanning Calorimetry: https://store.astm.org/e1356-23.html (checked 2026-10-29; the listing shows E1356-25 as the active edition).
- ASTM International, E794 Standard Test Method for Melting And Crystallization Temperatures By Thermal Analysis: https://store.astm.org/e0794-06r18.html (checked 2026-10-29; the listing shows E794-24 as the active edition).
