Meaning
International standards for determining the dynamic mechanical properties of plastics describe the methods found in this document. Compliance with iso 6721 ensures that measurements of stiffness and damping are consistent across different laboratories and equipment types. The standard covers various modes of deformation, including tensile, flexural, shear or compression loading across a range of temperatures and frequencies.
Protocol Standardization
Defined specimen geometries and loading rates provide the framework for repeatable data collection. These rules prevent variations in results that would otherwise arise from different sample preparation techniques.
Viscoelastic Response
Measuring the phase lag between applied stress and resulting strain allows for the separation of the storage modulus from the loss modulus. This data shows how a material stores energy elastically and dissipates it as heat. The tangent of the phase angle identifies the glass transition temperature and other secondary relaxations.
Such curves are far more descriptive than a single-point modulus value found on a standard datasheet.
Process Prediction
Verification is necessary when swapping resins for a high-performance application. Understanding the damping characteristics helps in designing parts for vibration sensitive environments. Moulders rely on these standardized tests to verify that a specific resin grade will maintain its structural properties at the high end of its operating temperature range.
