Rheology is an interdisciplinary field which draws on
mathematics and differential geometry, chemistry, thermodynamics, polymer science and mechanics of continua.
It includes as special cases hydrodynamics and theory of
elasticity while studying more general cases of viscoelastic materials and of non-linear and complex fluids.
Derivation of the constitutive equation from the microscopic properties, the structure-property relationship of materials
or ''structural rheology'' generalises methods of statistical mechanics from study of N-particle systems to more complex ensembles, e.g. to three-dimensional networks of polymer chains to derive equations of rubber elasticity.
Rheology is science of flow, of deformation of liquids and
solids, and of the in-between viscoelastic materials, such as asphalt, glass, dough or plastics (polymers).
The properties of the materials are described by the
constitutive equation (rheological equation of state)
which may an include other then mechanical quantities, such
as magnetic or electrical fields. Constitutive equation describes the memory of materials, effects of thermal and stress history and effects such as hysteresis.