Overview
ISO 3219-2:2021 - Rheology: Part 2 defines the general principles of rotational and oscillatory rheometry. It sets out measuring principles, symbols, terms and definitions, and the structure of measuring assemblies used to determine rheological properties such as shear viscosity, shear stress, shear rate, and viscoelastic parameters. Detailed practical information is provided in Annex A, and the document references ISO 3219-1 for general terms and definitions.
Key topics and technical requirements
- Measuring principles: Distinguishes rotational (steady or variable loading) and oscillatory tests (imposed oscillatory strain or stress) and explains controlled-deformation (CD), controlled-rate (CR) and controlled-stress (CS) test modes.
- Basic equations: Includes core relations for shear stress (τ = F/A), shear rate (γ̇ = v/h), and viscosity (η = τ/γ̇) using the two-plate model; defines sinusoidal strain and stress relationships in oscillatory tests and the loss angle δ.
- Rheological parameters: Defines elastic (storage) modulus G′, viscous (loss) modulus G′′, complex viscosity |η*| and loss factor tan δ for viscoelastic characterization.
- Measuring assembly requirements: Coverage of temperature control systems, measuring geometries and accessories. Geometries include absolute measuring geometries (where flow profiles and rheological parameters can be calculated exactly) and relative measuring geometries (where they cannot). Specific geometries addressed include cone‑plate, coaxial cylinders and plate‑plate configurations.
- Geometric and mechanical factors: Introduces symbols and factors such as the flow field coefficient (k), strain factor, shear stress factor, geometry compliance and torsional compliance.
- Practical influences: Terms and phenomena like no‑slip condition and wall slip are defined; measurement artefacts (bearing friction, transducer inertia, drive losses) are identified and quantified via defined symbols.
Applications and users
ISO 3219-2 is relevant for:
- Materials scientists and rheologists characterizing fluids and soft solids (paints, varnishes, polymers, coatings, pastes).
- QA/QC laboratories and test houses establishing reproducible rheological test methods.
- Instrument manufacturers (rotational/oscillatory rheometers) designing compliant measuring assemblies and reporting test performance.
- R&D teams optimizing formulations where viscosity and viscoelastic behavior (G′, G′′, tan δ) affect processing and end‑use performance.
Practical applications include formulation development, process control, quality acceptance testing, and comparative material evaluation using standardized rotational and oscillatory rheometry procedures.
Related standards
- ISO 3219-1: General terms and definitions for rotational and oscillatory rheometry (normative reference).
- Other parts of the ISO 3219 series (background and application‑specific parts) are in preparation and provide further guidance.
Keywords: ISO 3219-2, rheology, rotational rheometry, oscillatory rheometry, shear viscosity, shear stress, shear rate, G′ G′′, rheometer, measuring geometries, cone-plate, plate-plate, coaxial cylinders.
