Overview - ISO 11357-4:2021 (DSC - Specific heat capacity of plastics)
ISO 11357-4:2021 specifies accepted laboratory methods for determining the specific heat capacity (cp) of plastics using differential scanning calorimetry (DSC). The standard defines the measurement principle, apparatus and specimen requirements, two measurement modes (continuous‑scanning and stepwise‑scanning), calibration practice, baseline adjustment, calculation and reporting rules. It is part of the ISO 11357 DSC series for thermal analysis of plastics.
Key topics and technical requirements
- Measurement principle: Each cp determination uses three runs at the same scan rate - a blank run, a calibration run (calibration material in the sample holder), and a specimen run. The specific heat is derived from differences in heat flow and known masses.
- Calibration material: α‑alumina (synthetic sapphire) of high purity (≈99.9 %) is the recommended calibration material to establish reference heat capacity.
- Scan modes:
- Continuous‑scanning method - single continuous temperature ramp with baseline stabilization before and after the ramp.
- Stepwise‑scanning method - small temperature intervals with integration of heat flow over each interval; not suitable across first‑order phase transitions.
- Apparatus and crucibles: DSC apparatus per ISO 11357‑1. Crucibles for specimen and reference must be identical and their total masses must not differ by more than 0.1 mg (or corrections applied).
- Test conditions: Guidance on start/end temperatures, heating/scanning rates, dwell times for isothermal baselines (typical dwell times 2–10 min), sensitivity settings and temperature increments (commonly 5 K or 10 K).
- Data handling: Procedures for baseline adjustment, numerical rounding, precision and bias assessment, and required test report content are specified.
Practical applications and users
- Who uses it: Polymer scientists, R&D labs, materials testing laboratories, quality control engineers, thermal analysts, regulatory bodies, and instrument manufacturers.
- Why it’s used:
- Obtain reliable cp data for thermal modelling, heat‑transfer simulations and process design (moulding, extrusion).
- Compare materials for thermal management or insulation properties.
- Support materials selection, certification and failure analysis in automotive, packaging, electronics and building sectors.
- Provide standardized cp data for research, product development and quality assurance.
Related standards
- ISO 11357‑1 - DSC general principles (referenced for apparatus and basic DSC practice)
- ISO 472 - Plastics vocabulary
- ISO 80000‑1 - Quantities and units
Keywords: ISO 11357-4:2021, differential scanning calorimetry, DSC, specific heat capacity, plastics, cp measurement, α-alumina calibration, continuous scanning, stepwise scanning, thermal analysis.