Overview
ISO 6721-12:2022 - "Plastics - Determination of dynamic mechanical properties - Part 12: Compressive vibration - Non-resonance method" specifies a laboratory method to measure the compressive complex modulus E* of polymers using a non‑resonance compressive vibration technique. The standard covers measurements typically from 0.01 Hz to 100 Hz and is applicable to semi‑rigid plastics with dynamic storage moduli in the range 1 MPa to 1 GPa. It is especially suited for right‑angled prisms, cylinders or tubes and for studying temperature‑ and frequency‑dependent viscoelastic behavior across the glass–rubber transition.
Key topics and technical requirements
- Principle: Apply a sinusoidal compressive force or displacement well below the specimen’s fundamental resonance; measure force, displacement and phase angle to calculate E′ (storage modulus), E″ (loss modulus) and tan δ (loss factor).
- Frequency & modulus ranges: Typical frequency 0.01–100 Hz; storage modulus measurement range 1 MPa–1 GPa.
- Test device & transducers:
- Loading assembly with vibrator, compression plates and force/displacement transducers.
- Compression plate finish: Ra = 0.25 µm, parallel surfaces.
- Transducer calibration traceable to national standards; calibration accuracy ±2% for minimum amplitudes.
- Data acquisition accuracy: amplitude ±0.5%, phase ±0.05°, frequency ±1%.
- Temperature control:
- Temperature‑controlled enclosure with recommended range (example) −100 °C to +250 °C; temperature measurement to ±0.5 °C.
- Tests can be run as temperature sweeps to capture relaxation behavior.
- Specimen geometry & preparation:
- Shapes: right prism, cylinder or tube; length/width (or diameter) ratio between 1 and 2 (preferably 1).
- Dimensional measurement accuracy ±0.5% or ±0.05 mm.
- Machined ends must be flat, parallel and perpendicular to the axis.
- Procedure, calculations & reporting: Steps for mounting, preloading, performing tests, computing E′, E″, tan δ, presentation vs temperature/frequency, precision and required test report items.
Practical applications
- Characterizing viscoelastic and damping properties of semi‑rigid polymers for product design and material selection.
- Studying glass‑rubber transition and temperature/frequency dependence of compressive moduli.
- Quality control and comparative testing for automotive, aerospace, electronics, consumer goods, vibration‑isolation components, and polymer R&D.
- Input data for finite element models where compressive dynamic properties and loss factors are needed.
Who uses this standard
- Materials testing laboratories and conformity assessment bodies
- Polymer R&D and formulation scientists
- Product designers and mechanical engineers working on vibration and damping
- Manufacturers needing standardized test methods for specifications and regulatory compliance
Related standards
Keywords: ISO 6721-12:2022, compressive vibration, non-resonance method, dynamic mechanical properties, compressive complex modulus, storage modulus, loss factor, polymers, semi-rigid plastics.
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