ISO 1183-3:1999

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

• ISO 1183-1: Immersion, pyknometer and titration methods
• ISO 1183-2: Density gradient column method

Note: Follow safety and local regulations when using high-pressure gases and laboratory equipment.