ISO 22007-7:2023

Overview

ISO 22007-7:2023 - "Plastics - Determination of thermal conductivity and thermal diffusivity - Part 7" - specifies a transient, plane-heat-source method for measuring thermal effusivity of plastics and polymer-based materials. The method uses a self-heated planar probe (combined heater and resistance thermometer) embedded in or between specimens and records the transient temperature response after a single-step heat pulse. The standard covers materials with thermal effusivity roughly from 40 to 40 000 W·s1/2·m−2·K−1 and temperatures from 50 K to 1000 K.

Key topics and technical requirements

• Measurement principle: Single-step heat pulse with a planar probe acting as both heater and temperature sensor; analysis of temperature vs. time to derive the normal-direction thermal effusivity (b = sqrt(λ · ρ · cp)).
• Two experimental configurations:
  • Configuration A (rod-shaped specimens) - for higher-effusivity materials (≈ > 1 000 W·s1/2·m−2·K−1). Typical cross-section area ~7 mm² up to ~1 000 mm²; rod lengths ~3 mm to ~100 mm. Probe cross-section should match specimen cross-section.
  • Configuration B (bulk specimens) - for lower-effusivity materials (≈ < 1 000 W·s1/2·m−2·K−1). Typical specimen cross-sections ~2 000 mm² to ~50 000 mm²; thickness ~3 mm to ~30 mm. Specimen must completely embed the probe with specified margins.
• Apparatus and probe design: Follows requirements of ISO 22007-2 (hot disc / transient plane heat source), but allows probe shape variation (cylindrical, square, rectangular) provided heat distribution is uniform across the probe area.
• Specimen preparation and probing depth: Guidance on matching specimen geometry and probe area, controlling probing depth, and considering volumetric heat capacity and heat losses to surroundings.
• Quality controls: Calibration, verification procedures, precision and bias assessment, and required test report contents.

Practical applications

• Measuring directional thermal effusivity for plastics, composites, layered materials and anisotropic rods.
• Characterizing thermal interface materials (TIM) in stacked configurations to reflect real application performance.
• R&D and quality control for industries where heat transfer properties of polymers matter: electronics cooling, automotive, aerospace, thermal management systems, and materials development.
• Useful for small/irregular specimens and composite structures where conventional steady-state methods are impractical.

Who should use this standard

• Materials scientists and polymer engineers measuring thermophysical properties.
• Test laboratories performing thermal characterization for product development or certification.
• Designers of thermal management solutions and suppliers of TIMs and polymer-based insulators.

Related standards

• ISO 22007-1 - General principles for determination of thermal conductivity and diffusivity.
• ISO 22007-2 - Transient plane heat source (hot disc) method (referenced for apparatus and basic methodology).

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