Similarly describes creep. A logical step forward is therefore is therefore to find some combination of these two basic models which can account for both phenomena. A simple model which does this is known as the standard linear solid, one example of which is shown in Fig. 5.7(C). In this case a Maxwell element and spring are in parallel. The presence of the second spring will stop the tendency of the Maxwell element undergoing simple viscous flow
There have been many attempts at devising more complex models which can give a better representation of the viscoelastic behavior of polymers. As the number of elements increases the mathematics becomes more complex. It must be stressed that the mathematical models only give a mathematical representation of the mechanical behavior and as such do not give much help in interpreting the viscoelastic properties on a molecular level.