Overview
ISO 22007-3:2008 - Plastics: Determination of thermal conductivity and thermal diffusivity - Part 3 describes the temperature wave analysis method for measuring the thermal diffusivity of thin plastic films and plates in the through-thickness direction. The standard covers solids and melts, isotropic and orthotropic plastics, and thermal-diffusivity values from 1.0 × 10⁻⁸ m²/s to 1.0 × 10⁻⁴ m²/s. Measurements may be performed in air, inert atmospheres, reduced/elevated pressures or vacuum across a range of temperatures.
Key topics and technical requirements
- Measurement principle: generate a temperature wave by a.c. Joule heating on the front surface and detect its phase shift at the rear surface; thermal diffusivity is derived from phase-shift vs. frequency analysis.
- Specimen geometry: typical thin films 10 µm–500 µm thick, usually ~10 mm × 10 mm; thickness must be measured with a calibrated micrometer or appropriate gauge before testing.
- Apparatus components: heater and sensor resistive elements (preferably sputtered on opposite faces), backing plates for liquids, specimen holder, constant-temperature enclosure, function generator, lock-in amplifier and phase-shift measurement device.
- Performance limits and controls:
- Thermal-diffusivity range: 1.0 × 10⁻⁸ to 1.0 × 10⁻⁴ m²/s.
- Temperature stability of enclosure: specimen temperature change ≤ ±1 K during measurement.
- Heater power adjusted to limit specimen temperature rise to ≤ 1 K.
- Sensor bias current: 1 µA to 10 mA.
- Recommended phase-shift accuracy: ±0.01°; frequency accuracy better than 50 ppm.
- Specimen states: suitable for solid or molten plastics and for isotropic or orthotropic materials.
- Calibration & uncertainty: standard includes provisions for calibration, verification and uncertainty analysis (see Annexes for mathematical background and uncertainty examples).
Applications and users
- Practical uses:
- R&D and material development for thin polymer films, coatings and membranes.
- Thermal characterization in electronics, packaging, nanotechnology and biomedical polymers.
- Quality control and comparative testing of thin plastic components and melts.
- Typical users:
- Materials scientists, polymer engineers, thermal analysts, test laboratories and calibration facilities needing accurate through-thickness thermal-transport data.
- Advantages: high sensitivity and good temperature resolution for small or thin specimens where conventional bulk methods are unsuitable.
Related standards
- ISO 22007-1 - General principles for thermal conductivity/diffusivity of plastics.
- ISO 22007-2 - Transient plane heat source (hot disc) method.
- ISO 22007-4 - Laser flash method.
- Normative references: ISO 472 (plastics vocabulary), ISO 80000-5 (quantities & units - thermodynamics), ISO/IEC Guide 98-3 (GUM:1995, uncertainty).
Keywords: ISO 22007-3:2008, temperature wave analysis, thermal diffusivity measurement, plastics thin films, thermal transport properties, through-thickness thermal diffusivity.