Differential Scanning Calorimeter (DSC) for Chemical Reactivity Testing
Differential Scanning Calorimetry (DSC) is a technique used to measure changes in material heat generation as a function of time and temperature. These heat changes are often associated with reactions or transitions in materials.
The DSC is used primarily to determine glass transition temperatures, melting and boiling points, heat of fusion and specific heat. This data can be used directly in process optimization and in kinetic studies of reactive chemicals, to predict product performance and chemical degradation characteristics.
The data measurements from the equipment provide quantitative and qualitative information about physical and chemical changes that involve exothermic or endothermic processes, or changes in heat capacity. DSC test provides
- Onset temperature
- Heat flow rate
- Heat of melt / crystallization
- Latent heat of evaporation
- Melting/boiling temperature
- Enthalpy of endotherm
- Enthalpy of exotherm
Standards / References:
ASTM E537 “Standard Test Method for the Thermal Stability of Chemicals by Differential Scanning Calorimetry”
Equipment used:
- DSC 204 F1 Phoenix (Differential Scanning Calorimeter manufactured by Netzsch™ Group of Selb, Germany)
- DSC 2910 Modulated by TA Instrument
- High pressure sample crucible (Picture 1)
DSC
High pressure sample crucible
Test details:
Different techniques are employed depending on whether an open or closed test is desired. For closed tests, approximately 5-20 mg of the sample is introduced into a high-pressure stainless-steel crucible (110 bar), material of construction could be aluminum, stainless-steel, titanium. All the battery material samples are prepared under argon environment. The crucible is placed into the instrument alongside an empty reference crucible. Temperature vs. time is recorded for both systems along with heat flow (mW/mg). Temperature or heat flow differences between them indicate exotherm or endothermic behavior.
The DSC most frequently operates in a scanning mode, ranging from 1-20 °C/min. Operator skill ensures proper calibration. The instrument is fully automated; once operating, it needs minimal to no operator intervention. Various atmospheres can be imposed during open tests.
Some details on the DSC include:
- Test cell material options include aluminum (open), stainless steel, and gold plated
- Operating test cell temperature range: room temperature to 500°C
- Temperature Accuracy: +/-0.1°C
- Scanning operating mode: ranging from 1-20 °C/min (10 °C/min)
- Operating test cell pressure range: 0 to 110 bar
- Sample size: 10 mg standard
- Data recorded is generally in heat flow (W/g) vs. temperature (°C)
Example Test:
Graphite and graphite fiber anode samples recovered from multiple coin cell at fully charged state were tested in a high-pressure crucible. Scan heat mode of 10 °C/min were used. The test results of DSC tests are summarized in Table 1 and comparative plots are shown in Figure 1. Test results indicate that both the samples had three exothermic reactions between 100°C and 400C. First exotherm was of interest for this study and results are summarized in Table 1.
Table 1: DSC Test Results of Lithiated Anode Sample
| Parameter | Description | Results | |
|---|---|---|---|
| Lithiated Graphite | Lithiated Graphite Fiber | ||
| To | Onset temperature of enthalpy change, °C | 110 | 112 |
| Tp | Peak temperature, °C | 133 | 135 |
| Te | Peak end temperature, °C | 152 | 160 |
| ΔE | Change in enthalpy, J/g | 136 | 292 |
Figure 1: Comparative DSC Plot of two Lithiated Anode Samples
FAQ:
1. How does ARC differ from DSC testing?
While Differential Scanning Calorimetry (DSC) provides screening data at small sample scales, ARC replicates adiabatic conditions to simulate real-world runaway behavior — offering more accurate insight into large-scale hazards.
2. What kind of samples can be analyzed using DSC?
Solids, liquids, powders, and polymers—typically stable at room temperature. Reactive chemicals or energetic materials require specialized high-pressure or sealed crucibles.
3. How is DSC used in process safety or chemical reaction hazard analysis?
DSC identifies whether a substance undergoes self-heating, exothermic decomposition or polymerization, or incompatible reactions at process or storage temperatures—guiding safe temperature limits (TMR, SADT, etc.) and pressure relief design.
4. How does DSC differ from TGA (Thermogravimetric Analysis)?
DSC measures heat flow associated with transitions, while TGA measures weight changes with temperature (e.g., due to evaporation or decomposition).
5. What are the limitations of DSC?
- Small sample size may not represent bulk behavior.
- Cannot measure pressure evolution directly.
- Not ideal for very slow or gas-evolving reactions.
- Requires complementing tests (e.g., ARC, VSP2 and APTAC) for full hazard analysis.