Physical Properties Evaluation of Polymer Materials by Temperature-Modulated DSC

Significance of the Topic

Temperature‐modulated differential scanning calorimetry (TM‐DSC) enhances the capabilities of standard DSC by deconvoluting overlapping thermal phenomena. This is critical for polymer science, where transitions such as glass transition, melting, recrystallization and curing often occur in close temperature ranges. TM‐DSC enables precise characterization of specific heat changes and reaction enthalpies, supporting material development, quality control and research in analytical chemistry.

Objectives and Study Overview

The article presents an application note (No. T156) demonstrating the use of TM‐DSC with the Shimadzu DSC-60 Plus system. Representative polymer materials—including polyethylene terephthalate (PET), nylon 6 and epoxy resin adhesives—were evaluated to illustrate how modulation separates reversing and non‐reversing heat flows, thereby clarifying complex thermal events.

Methodology

A small‐amplitude sinusoidal temperature modulation is superimposed on a constant heating rate. The resulting data are processed by the LabSolutions TA analysis software to yield:

• Reversing heat flow, corresponding to changes in specific heat (e.g. glass transitions, melting).
• Non‐reversing heat flow, representing enthalpic events (e.g. crystallization, curing reactions).
• Total heat flow, equivalent to standard DSC output.

Used Instrumentation

• Shimadzu DSC-60 Plus differential scanning calorimeter
• LabSolutions TA software for TM-DSC data analysis

Main Results and Discussion

1. PET Analysis

• Heating rate: 2 °C/min, modulation: ±0.2 °C over 40 s cycle.
• Total heat flow showed overlapping glass transition and enthalpy relaxation around 75 °C.
• Reversing curve isolated the baseline shift from glass transition; non‐reversing curve highlighted the enthalpy relaxation peak.
• Non‐reversing data revealed exothermic recrystallization near 117 °C and melting‐related exotherm around 231 °C.

2. Nylon 6 Behavior

• Samples cooled at −30 °C/min, heated at 2 °C/min with ±0.5 °C modulation over 80 s.
• Total heat flow displayed overlapping recrystallization (∼193 °C) and melting (∼222 °C) peaks.
• TM-DSC separated recrystallization in the non-reversing channel and melting in the reversing channel.

3. Epoxy Resin Adhesive Curing

• Two curing times at room temperature: 4.5 h and 42 h. Measurements at 3.5 °C/min with ±0.5 °C modulation over 60 s.
• Total heat flow showed glass transition shifting from −19 °C (4.5 h) to ∼32 °C (42 h) and decreasing curing exotherm.
• Reversing and non-reversing curves distinctly separated glass transition baseline shifts from exothermic curing peaks.

Benefits and Practical Applications

• Clear separation of overlapping thermal events improves accuracy in determining transition temperatures and reaction enthalpies.
• Enhanced detection of subtle enthalpy changes (e.g. enthalpy relaxation) that may be missed in standard DSC.
• Valuable tool for polymer formulation, processing optimization, quality control and failure analysis.

Future Trends and Possibilities

• Integration of TM-DSC with hyphenated techniques (e.g. TM-DSC-FTIR) for simultaneous thermal and chemical analysis.
• Development of advanced modulation programs and higher throughput configurations for rapid screening.
• Application to a wider range of materials including biopolymers, composites and nanomaterials.
• Machine learning–based analysis of complex TM-DSC data for automated event identification.

Conclusion

TM-DSC significantly extends the analytical power of standard DSC by separating reversible and irreversible thermal events. The case studies on PET, nylon 6 and epoxy adhesives demonstrate improved resolution of transitions and reactions, facilitating more detailed characterization and process monitoring of polymeric materials.

References

• Shimadzu Application Note No. T156: "Physical Properties Evaluation of Polymer Materials by Temperature‐Modulated DSC"