Overview
ISO 1183-3:1999 - "Plastics - Methods for determining the density of non-cellular plastics - Part 3: Gas pyknometer method" specifies a standard test method for determining the density or specific volume of solid, non‑cellular plastics of any shape that do not contain closed pores. The method uses a gas pyknometer (pressure- or volume-measuring) to determine specimen volume by measuring gas volume or pressure change when the specimen is introduced. Results are used to calculate density at a stated temperature.
Keywords: ISO 1183-3:1999, gas pyknometer, density of non-cellular plastics, plastics density measurement, pyknometer method.
Key Topics
- Scope and applicability
- Solid, non-cellular plastics without closed pores; any specimen shape.
- Principle
- Volume change in a pyknometer upon specimen insertion is measured directly or via pressure changes (ideal gas law).
- Gases with low adsorption (preferably helium) are recommended.
- Apparatus & materials
- Analytical balance (0.1 mg accuracy).
- Gas pyknometer sized to specimen; recommended accuracy ~0.01% of cell volume.
- Measurement gas (helium 99.99% preferred) and thermostatic control (typically 23 °C ±1 °C).
- Specimen preparation
- Dry to constant mass if required; avoid closed pores (grind if needed).
- Condition specimens where density is sensitive to humidity, thermal history or crystallinity.
- Calibration & procedure
- Calibrate pyknometer using a specimen of known density or volume; recalculate if cell volume, temperature, gas type or pressure change.
- Measure three or more specimens; calculate mean density and standard deviation using the calibration factor.
- Precision & reporting
- Formal inter-laboratory precision not available; expected repeatability ≈0.1% and reproducibility ≈0.2% (informative).
- Test report must include method reference, specimen ID, conditioning, gas and purity, temperature, pyknometer type, calibration details and results.
Applications
- Determining polymer density for quality control, material characterization and batch comparison.
- Estimating degree of crystallinity and filler content in plastics.
- R&D where precise volume/density measurements inform processing or materials selection.
- Useful in laboratories, compounders, polymer producers, independent testing houses and certification bodies.
Who uses it: materials scientists, polymer engineers, QA/QC laboratories, test labs, and standards bodies involved in plastics characterization.
Related Standards
Note: Follow safety and local regulations when using high-pressure gases and laboratory equipment.
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