Overview
ISO 19935-3:2021 - "Plastics - Temperature modulated DSC - Part 3: Separation of overlapping thermal transitions" specifies a standardized TM‑DSC method for separating overlapping thermal events in plastics into reversing (heat‑capacity related) and non‑reversing (kinetic) heat flow components. The method uses temperature modulated differential scanning calorimetry (TM‑DSC) to improve interpretation of transitions such as glass transition, cold crystallization, melting and other kinetic processes.
Key topics and technical requirements
- Principle: Separate the total heat flow rate into reversing and non‑reversing components by modulating the heating rate. Reversing = heat capacity component; non‑reversing = kinetic component. Separation is effective for effects on the time scale of the chosen modulation.
- Apparatus & materials: Equipment and sample handling in accordance with ISO 19935‑1 and ISO 11357‑1.
- Calibration: Follow ISO 19935‑1 and ISO 19935‑2 for general calibration, modulation amplitude and phase calibration, and for specific heat capacity measurement.
- Procedure: Specimen preparation, instrument setup and measurement procedures follow ISO 11357‑1 and ISO 19935‑1/‑2. Key experimental parameters include underlying heating rate, modulation frequency, amplitude and waveform.
- Data interpretation: Guidance on interpreting reversing vs non‑reversing heat flow, with examples (e.g., quenched PET) showing how cold crystallization and melting appear in the non‑reversing signal while glass transition appears in reversing heat capacity.
- Reporting: Test reports must reference ISO 19935‑3:2021 and include specimen identification, instrument type/model, crucible details, purge gas, calibration details, sample mass and history, temperature program (frequency/amplitude/waveform), and plots of total, reversing and non‑reversing heat flow.
Practical applications and users
- Materials research: Resolve overlapping transitions in polymers to better characterize glass transition, crystallization and melting behavior.
- Quality assurance & production testing: Routine checks of raw materials and finished plastic products where clearer separation of thermal events improves pass/fail decisions.
- Failure analysis & R&D: Distinguish kinetic processes (e.g., crystallization, reactions, enthalpy relaxation) from heat‑capacity changes for formulation development and troubleshooting.
- Instrument manufacturers and testing labs: Implement standard TM‑DSC procedures, calibrations and reporting to ensure reproducible and comparable results.
Related standards
Keywords: ISO 19935-3:2021, temperature modulated DSC, TM‑DSC, plastics, reversing heat flow, non‑reversing heat flow, separation of overlapping thermal transitions, DSC, specific heat capacity.