Overview
EN ISO 1183-3:1999 - Plastics - Methods for determining the density of non-cellular plastics - Part 3: Gas pyknometer method (ISO 1183-3:1999) specifies a laboratory method to determine the density (or specific volume) of solid, non-cellular plastics of any shape that do not contain closed pores. The standard describes the principle, required apparatus, specimen preparation, calibration, measurement procedure and test reporting requirements for gas pyknometer measurements (pressure- or piston-type). It is widely used for accurate polymer density measurement and material characterization.
Key topics and requirements
- Scope and principle: Determine specimen volume by measuring the change in gas volume or pressure in a pyknometer when a test specimen is introduced; density = mass / volume. The method relies on the pressure–volume relationship for gases (ideal gas law).
- Apparatus and materials:
- Analytical balance (accuracy 0.1 mg).
- Gas pyknometer with cell-volume accuracy (example: 0.01% of cell volume).
- Measurement gas - helium recommended (≥ 99.99% purity) or other non-adsorbing, non-corrosive gases (e.g., dry air), operating pressures up to ~300 kPa.
- Thermostatic control (preferably 23 °C ±1 °C) or built-in temperature control.
- Specimen preparation:
- Dry to constant mass unless otherwise specified.
- Test powders/granules may be measured as received; solid shapes can be cut to fit cell.
- Avoid introducing closed pores (grind if necessary).
- Calibration and procedure:
- Calibrate the pyknometer using a specimen of known volume or density; recalibrate if temperature, gas, pressure or cell volume change.
- Perform measurements on three or more specimens; calculate mean density and standard deviation.
- Accuracy and precision:
- Precision statement pending inter-laboratory data; expected repeatability ≈ 0.1% and reproducibility ≈ 0.2% (indicative).
- Reporting: Report must reference ISO 1183-3 and include material identification, mean density and standard deviation, specimen masses, conditioning, gas and purity, temperature, calibration material, pyknometer type/manufacturer, any deviations and test date.
Applications and users
- Practical uses: polymer density determination, evaluation of degree of crystallinity, estimation of filler content, quality control, material specification and R&D comparisons.
- Typical users: materials testing laboratories, polymer manufacturers, quality engineers, R&D scientists, certification bodies and standards organizations requiring reliable polymer density measurement using gas pyknometer techniques.
Related standards
- ISO 1183 (series) - other parts for density determination:
- Part 1: Immersion, pyknometer and titration methods
- Part 2: Density gradient column method
- Reference keywords: EN ISO 1183-3:1999, ISO 1183-3, gas pyknometer, density of plastics, polymer density measurement, pyknometer method.
