Overview
ISO 19935-1:2018 - Plastics - Temperature modulated DSC - Part 1: General principles defines the general principles for using temperature-modulated differential scanning calorimetry (TM‑DSC) for plastics. It describes the measurement principle and apparatus, sampling, calibration and reporting conventions that are common to the ISO 19935 series. Part 1 is deliberately focused on fundamentals; details for specific test methods are reserved for subsequent parts of the series.
Key topics and technical requirements
- Measurement principle: Difference in heat flow between specimen and reference under a controlled, periodic temperature modulation superimposed on an underlying heating/cooling rate.
- Temperature modulation modes: Variable heating-rate modulation, sinusoidal and non‑sinusoidal waveforms, single- and multi-frequency modulation.
- Calculation of heat flow and heat capacity: Treatment of underlying and periodic heat-flow components; extraction of apparent and complex heat capacity (real and imaginary parts or magnitude/phase).
- Reversing vs non‑reversing signals: Separation of reversible (heat capacity related) and non‑reversible (kinetic or latent heat) contributions.
- Instrument considerations and calibration: Requirements for modulation amplitude and phase calibration, frequency-dependent calibration factor K(ω), and the effect of instrument time constants on analysis.
- Time‑dependent behavior: Handling non‑equilibrium processes (relaxation, vitrification) via time‑dependent heat capacity and frequency-domain (Fourier) treatment.
- Procedure and reporting: General experimental conditions, interpretation guidance, and required elements for the test report to ensure comparability and traceability.
- Normative references and theory: Links to ISO 472 (vocabulary), ISO 11357-1 (DSC general principles) and theoretical background (Annex A).
Practical applications and users
ISO 19935-1 is intended for laboratories and organizations performing thermal analysis of polymers. Typical applications include:
- Characterizing glass transition, melting, crystallization and cold crystallization.
- Measuring heat capacity and separating overlapping thermal transitions.
- Monitoring curing or cross‑linking reactions in thermosets and elastomers.
- Quality assurance, raw-material checks and preparation of data sheets/databases.
- Research and development where improved resolution of overlapping events or kinetic contributions is required.
Who uses it:
- Polymer scientists and materials engineers
- Thermal analysis and QA laboratories
- Instrument manufacturers and service providers
- Standards developers and regulatory bodies
Related standards
- ISO 11357-1 - Plastics: Differential scanning calorimetry (general principles)
- ISO 472 - Plastics: Vocabulary
- ISO 80000-5 - Quantities and units (thermodynamics)
Keywords: ISO 19935-1, temperature modulated DSC, TM-DSC, modulated differential scanning calorimetry, plastics thermal analysis, heat capacity, complex heat capacity, calibration, polymer testing.