Rheological properties mathematical characterization

The fundamental rheological characterization of a material requires the experimental determination of a constitutive equation (a rheological equation of state) that mathematically relates stress and strain, or stress and strain rate. The constants in the constitutive equation are the rheological properties of the material. 

A dynamic mechanical analyzer (DMA) is a controlled-stress or con-trolled-strain instrument that provides information on mechanical properties such as modulus, energy dissipation, and material stability. This versatile instrument is able to perform studies of materials in both the melt and solid states. Melt-state studies have been covered earlier, in the introduction to rheology. DMA is a powerful technique for developing a fundamental understanding of polymer behavior. A vast amount of research has led to the development of a mathematically rigorous science that allows for the characterization of polymers as well as the extrapolation of properties. 

---