Why Choose Modulated Differential Scanning Calorimetry (MDSC)? MDSC transforms standard DSC into a comprehensive analytical tool by separating Total Heat Flow into Reversing and Non-Reversing components. MDSC allows you to improve both sensitivity and resolution simultaneously [1].

However, achieving maximum benefit requires optimal experimental conditions [2]. The three critical parameters—Period, Heating Rate, and Amplitude—must be selected based on your specific requirements and instrument limits.

How to Choose Modulation Parameters

1. Define the Event Range: First, estimate the temperature range of the transition you are analyzing. 

2. Optimize Cycles: Adjust the Period and Heating Rate sliders to achieve 4–6 modulation cycles within that temperature range. A higher number of cycles increases resolution. Use the interactive display below to visualize these cycles. Note: A period of 40s or greater is recommended to maintain calibration constants [2]. 

3. Set the Amplitude: Increase the amplitude to improve sensitivity. Higher amplitude generates a higher instantaneous heating rate (shown as the magenta curve in the bottom-right panel).

• Check Limits: Ensure the highest and lowest instantaneous heating rates are within your instrument's capabilities.

• Choosing a Modulation Mode: The relationship between amplitude and heating rate determines your mode:

(i). Heat-Cool (Lowest Heating Rate < 0 °C/min): Select this if you are analyzing a Glass Transition (Tg) or Heat Capacity (Cp).

(ii) Heat-Only (Lowest Heating Rate > 0 °C/min): Select this for Melting or to resolve simultaneous melting/crystallization events.

How to Use Quasi-Isothermal MDSC (Time-Dependent Events) Quasi-isothermal MDSC equilibrates the sample at a specific temperature to study time-dependent events [3].

• To demonstrate: Set the Heat Rate to 0 in the panel below.

• Setup: Select a specific Period and Amplitude. While lower temperature amplitudes ensure isothermal conditions, higher amplitudes (combined with lower periods) generally improve sensitivity.

References

[1] L. C. Thomas, Why Modulated DSC®? An Overview and Summary of Advantages and Disadvantages Relative to Traditional DSC, TA Instruments.

[2] Choosing Conditions in Modulated DSC®, TA Instruments

[3] L. C. Thomas, Measurement of Accurate Heat Capacity Values, TA Instruments

Please send any corrections or suggestions to mail.nskk@gmail.com 

You can view the temperature modulation and instantaneous heating rate corresponding to your parameter.