Meaning
An international standard outlines the experimental procedures for determining the dynamic mechanical properties of plastics under tensile vibration using non-resonance methods. The protocol of ISO 6721-4 provides measurements of the storage modulus, loss modulus, and loss factor as functions of temperature or frequency. This analytical framework enables polymer chemists to characterize transition regions and damping behavior in solid plastic specimens.
Testing Parameter
The method applies a sinusoidal tensile deformation to a strip of polymer while measuring the resulting force and phase angle. Laboratory technicians control the oscillation frequency and temperature ramp rates to generate reproducible sweep curves. This precise thermal analysis identifies the glass transition temperature with higher sensitivity than standard differential scanning calorimetry.
Resin Development
Raw material manufacturers use the standard to optimize resin formulations for vibration damping or high-stiffness applications. Comparative testing of different polypropylene grades helps compounders select appropriate elastomeric modifiers for impact resistance. The dynamic mechanical data generated helps engineers model part performance under cyclic loading.
Process Engineering
Injection moulders use this dynamic data to understand how parts behave during demoulding or subsequent machining. Modulus changes across the temperature range help determine the necessary cooling time before part ejection. This prevents post-molding warpage and ensures dimensional consistency.
