Overview
ISO 1675:2022 specifies a standardized laboratory method for determining the density of liquid resins used in plastics by the pycnometer method. The procedure measures the mass of resin contained in a calibrated pycnometer at 23 °C and applies an air-buoyancy correction to report density in grams per millilitre (g/ml) to three decimal places. The method is intended primarily for low- and medium-viscosity resins; it can be more difficult to apply to very high-viscosity materials.
Key topics and requirements
- Principle: Mass measurement of resin in a pycnometer of known volume at 23.0 °C.
- Apparatus:
- Pycnometer (graduated glass flask with ground glass stopper or stopper with capillary); volume accuracy 0.01% or better at 23.0 °C.
- Balance with 0.2 mg readability.
- Thermostatic device capable of maintaining (23.0 ± 0.1) °C.
- Transparent conical (Erlenmeyer) flask, 200–600 ml, for sample preparation.
- Procedure highlights:
- Prepare at least 150 g of resin and remove entrained air bubbles before and during temperature equilibration.
- Weigh the empty pycnometer, fill to the graduation mark ensuring no bubbles, equilibrate (wait ≥30 min), then weigh again.
- Apply an air buoyancy correction (ISO gives an air density value at 23 °C / 50 % RH) when calculating density.
- Expression of results:
- Density calculated by formula in the standard and reported to three decimal places (g/ml).
- The standard includes a method to verify or determine pycnometer volume using distilled water at 23 °C (water density given).
Practical applications
- Routine quality control and batch verification of liquid resins used in polymer production, coatings, adhesives, and composite formulations.
- Material data reporting for technical data sheets and regulatory documentation.
- Comparative laboratory testing when consistent, traceable density values at 23 °C are required.
Who should use this standard
- Materials and analytical laboratories performing plastics testing.
- Quality assurance and R&D teams in polymer, coatings, adhesives and composite industries.
- Certification bodies and suppliers who need reproducible density measurements for specifications or acceptance tests.
Related standards
- ISO 1183-1 - Methods for determining the density of non-cellular plastics (includes immersion and pycnometer methods).
Keywords: ISO 1675:2022, pycnometer method, density determination, liquid resins, plastics testing, 23 °C, air buoyancy correction, pycnometer volume.
