Overview
EN ISO 22007-4:2024 - "Plastics - Determination of thermal conductivity and thermal diffusivity - Part 4: Light flash method" specifies a standardized laboratory method to determine the thermal diffusivity of thin solid plastic discs in the thickness direction using the light flash method. The technique measures the transient temperature rise at the rear face of a specimen produced by a short energy pulse on the front face and derives thermal diffusivity by comparing the recorded thermogram with theoretical models.
Key topics and requirements
- Scope and applicability
- Applies to homogeneous plastics and composites with isotropic or orthotropic structure.
- Typical covered diffusivity range: 1 × 10⁻⁷ to 1 × 10⁻⁴ m²·s⁻¹.
- Temperature range: −100 °C to +400 °C; measurements possible in gaseous or vacuum environments.
- Note: measured values for inhomogeneous specimens can be thickness dependent.
- Measurement principle
- A short, spatially uniform light pulse (previously called "laser flash", now "light flash") heats the front face; the rear-face thermogram (temperature vs time) is recorded.
- Key parameters: pulse width, time origin, half-rise time (t1/2) and maximum temperature rise (ΔTmax).
- Thermal diffusivity is obtained by data analysis against theoretical or numerical models (see Annex B).
- Apparatus and calibration
- Core components: furnace or climatic chamber, flash source (e.g., laser/light pulse), pulse detector, transient IR detector, specimen holder and data acquisition/analysis unit.
- Requirements for thermal control (±0.5 K stability for ≥30 min) and measurement device performance are specified.
- Clauses cover specimen preparation, coating, thickness measurement, calibration/verification, and uncertainty estimation.
- Documentation
- Test report requirements and normative/ informative annexes (pulse correction, alternative calculation methods, specimen prep for mouldable thermoplastics/thermosets).
Applications and who uses it
- Materials testing laboratories and certification bodies for polymer thermal property data.
- R&D and quality control teams in plastics, composites, electronics packaging, automotive and aerospace industries.
- Use cases:
- Thermal characterization for heat-transfer modeling and simulation.
- Selection and development of insulating or thermally conductive polymeric materials.
- Performance assessment of composite laminates and orthotropic materials.
- Design validation for thermal management in electronics and transport components.
Related standards
- ISO 22007-1 (General principles for thermal conductivity/diffusivity testing)
- ISO 291 (Conditioning and testing atmospheres)
- ISO 527-1 (Tensile properties - general principles)
- ISO/IEC Guide 98-3 (Guide to the expression of uncertainty in measurement)
EN ISO 22007-4:2024 is the latest edition (supersedes the 2017 version) and reflects the updated terminology and procedural clarifications for consistent, reproducible measurement of polymer thermal properties.