Overview
ISO 15106-5:2015 - titled "Plastics - Film and sheeting - Determination of water vapour transmission rate - Part 5: Pressure sensor method" - specifies a laboratory method for measuring the water vapour transmission rate (WVTR) of plastic film, plastic sheeting, and multi‑layer structures using a pressure sensor. The method provides relatively rapid WVTR measurement across a wide range of permeability values by detecting pressure increase on the downstream side as water vapour permeates through the specimen.
Key topics and technical requirements
- Principle: A specimen seals two chambers (upstream and downstream). The upstream is filled with controlled water vapour; permeation is measured as pressure rise in the downstream chamber.
- Apparatus components:
- Transmission cell with constant transmission area (typical diameter 5–200 mm).
- Pressure sensor for downstream chamber (recommended sensitivity ~0.2 Pa).
- Water vapour generator with reservoir pressure sensor (min. sensitivity ~20 Pa).
- Cell volume‑control device (to extend measurement range) and vacuum pump (ultimate vacuum ≤ 1 Pa).
- Specimens & conditioning:
- Representative, defect‑free specimens; larger than the transmission area.
- Typical testing of three specimens unless agreed otherwise.
- Conditioning to the chosen test temperature and humidity prior to testing.
- Test conditions: Standard selectable conditions include 25, 40, 60 °C (all at 90% RH) and 85 °C at 85% RH (± specified tolerances).
- Procedure: Evacuate chambers, introduce water vapour upstream, record downstream pressure vs. time, determine steady‑state slope (dp/dt).
- Calculation: WVTR is calculated from downstream volume, transmission area, temperature and measured dp/dt (formula in clause 10).
- Quality controls: Background measurement (cell without sample) recommended; report must include apparatus, sample details, area, thickness, conditioning, and mean result.
- Precision: Interlaboratory precision not yet established (no precision statement in this edition).
Applications and users
ISO 15106-5 is applicable wherever accurate WVTR/WV permeability data are needed for plastic films and multilayer laminates. Typical users include:
- Packaging engineers assessing moisture barrier for food, pharmaceuticals, electronics.
- Materials scientists and R&D teams developing barrier films and coatings.
- Quality control and test laboratories performing standardized WVTR certification.
- Suppliers specifying barrier performance for multi‑layer structures.
Benefits include rapid measurement capability and suitability for a wide WVTR range; important when comparing barrier performance or validating new materials.
Related standards
- ISO 15106 series (other detection methods): Part 1 (humidity sensor), Part 2 (infrared), Part 3 (electrolytic), Part 4 (gas‑chromatographic), Part 6 (atmospheric pressure ionization MS), Part 7 (calcium corrosion).
- ISO 4593:1993 (thickness determination of films and sheeting) is referenced in the bibliography.