Overview
EN ISO 6721-2:2019 - Plastics: Determination of dynamic mechanical properties - Part 2: Torsion‑pendulum method (ISO 6721-2:2019) is a CEN-adopted international standard that specifies two torsion‑pendulum test methods (Method A and Method B) for measuring the linear dynamic mechanical properties of plastics. The standard determines the storage and loss components of the torsional modulus as a function of temperature for small deformations in the frequency range 0.1 Hz to 10 Hz. Temperature‑dependent results provide insight into polymer transition regions (for example, glass transition and melting) and the onset of plastic flow.
Key Topics
- Test scope: Linear dynamic torsional response for plastics (not suitable for rubbers or non‑symmetrical laminates).
- Methods A and B:
- Method A: inertial element suspended from the specimen.
- Method B: inertial element suspended from a wire; the wire is part of the oscillating system.
- Measured properties: torsional storage modulus (G') and loss modulus (G''), and logarithmic decrement (damping).
- Frequency and temperature: designed for 0.1–10 Hz; typical temperature ranges for many plastics can span approximately −50 °C to +150 °C (illustrative).
- Apparatus and instrumentation:
- pendulum/inertial element, clamps, oscillation‑inducing and recording devices,
- temperature‑controlled chamber and gas supply,
- equipment to measure specimen dimensions and temperature.
- Standard test procedures: specimen preparation, conditioning, mounting, temperature control, measurement, calculations and correction factors (damping, dimensional, longitudinal force), precision and reporting requirements.
Applications
- Materials characterization: determine glass transition temperature, secondary transitions, and viscoelastic behavior.
- Product development & R&D: compare polymer formulations, additives, fillers, and processing effects.
- Quality control & acceptance testing: batch verification of dynamic mechanical properties.
- Failure analysis & service life assessment: assess temperature-dependent stiffness and damping for parts under dynamic loading.
- Typical users: polymer scientists, materials engineers, mechanical designers, testing laboratories, and regulatory bodies requiring standardized dynamic mechanical analysis of plastics.
Related Standards
- ISO 6721-1 - General principles for dynamic mechanical property determination (normative reference).
- ISO 6721-3 - Addresses methods for non‑symmetrical laminates (this document’s methods are not applicable to such laminates).
- ISO 4664-2 - Recommended for dynamic testing of rubbers (EN ISO 6721-2 is not suitable for rubbers).
- Full ISO 6721 series for complementary test methods and guidance.
Keywords: EN ISO 6721-2:2019, torsion‑pendulum, dynamic mechanical properties, torsional modulus, storage modulus, loss modulus, plastics testing, viscoelasticity, glass transition.
