Overview - ISO 4590:2016 (Rigid cellular plastics - open/closed cell volume)
ISO 4590:2016 specifies a reproducible laboratory procedure to determine the volume percentage of open cells and closed cells in rigid cellular plastics. The standard requires measurement of the specimen’s geometrical volume (Vg) and its air-impenetrable volume (Vi), then uses those results to calculate the apparent and corrected open‑cell contents and the complementary closed‑cell percentage. ISO 4590 covers three alternative measurement methods for Vi (pressure variation and two volume‑expansion techniques), calibration, specimen preparation and conditioning, and reporting requirements.
Key technical topics and requirements
- Measurement principle: Vi is obtained by applying Boyle‑Mariotte law in a controlled, non‑deformable chamber first without and then with the specimen; Vg is measured from specimen dimensions.
- Methods specified:
- Method 1 - Pressure variation (pyknometer): uses differential pressure readings and a calibrated piston/scale system.
- Method 2a - Volume expansion (original technique) and Method 2b - Volume expansion (modernized apparatus): method 2b updates equipment and calibration procedures.
- Specimen preparation and quantity:
- Minimum of three test specimens; three tests per specimen.
- Cutting restrictions (no hot‑wire cutting) and removal of dust/skins; sectioning patterns to produce different surface/volume ratios.
- Typical specimen sizes: method 1 and 2b - 25 × 25 × 25 mm; method 2a - 100 × 30 × 30 mm (tolerances specified).
- Conditioning and atmosphere: condition samples ≥16 h at (23 ± 2) °C and (50 ± 5) % RH; tests should be performed at the same controlled conditions.
- Calculations and corrections:
- Compute apparent open‑cell percentage ω = (Vg − Vi) / Vg × 100.
- Plot ω versus surface/volume ratio r and extrapolate to r = 0 to obtain corrected open‑cell percentage ω0 (accounts for cells opened by cutting).
- Closed‑cell percentage ψ0 = 100 − ω0.
- Calibration, precision and test reporting: apparatus calibration, procedural notes, precision statistics and required test report contents are specified.
Applications and who uses ISO 4590:2016
- Quality control and batch testing for manufacturers of rigid cellular plastics (foam insulation, structural foams).
- Independent testing and certification laboratories performing open/closed cell content analysis.
- Materials researchers and product developers evaluating foam microstructure impact on thermal, acoustic and mechanical performance.
- Construction, HVAC and packaging sectors that require validated open/closed cell data for product selection and compliance.
Related standards
- ISO 1923 - for determination of linear dimensions used in calculating surface area and geometrical volume.
- Developed by ISO/TC 61/SC 10 (Cellular plastics).
Keywords: ISO 4590:2016, rigid cellular plastics, open cells, closed cells, impenetrable volume, pyknometer, volume expansion, foam testing, specimen conditioning.