On a class of constitutive equations for viscoelastic liquids

Simple rheological equations that describe non-linear viscoelastic phenomena in polymeric liquids have long attracted the attention of many rheologists. Although there are many ways of deriving such equations, only one concept is considered here. This concept is based on the introduction of an internal parameter, the recoverable strain tenson, and arises from a special kinematic study together with the formalism of irreversible thermodynamics. The main part of the paper sets out the theory for a single mode but a multimode extension is demonstrated towards the end and is compared with experimental data. Finally some of the problems that remain unsolved in the theory are discussed.The aim of this paper is to acquaint rheologists with the author's views as the model rheological equations he developed have recently been discussed in the literature without his participation.