Viscoelastic gels, Maxwell model

We will now consider the viscoelastic properties of silicone gels with a mechanical model. It is possible to express complex mechanical behaviors by properly connecting a spring and dashpot, which are the mechanical models for modulus and viscosity, respectively. The Maxwell model, which is the model to connect a spring and dashpot in series, continues to deform upon application of external force. It is therefore liquidlike and is convenient to express the mechanical properties of a sol, which has elastic properties. In contrast, the Voigt model, which is the model to connect a spring and dashpot in parallel, reaches a finite deformation and exhibits equilibrium. Hence, it is solidlike and is convenient to express a gel that shows loss in mechanical energy [201]. 

For a viscoelastic liquid with a single relaxation time, a Maxwell model can be made which relates the viscosity to the gel elastic modulus E and the stress relaxation time... 

Rheological measurements performed on highly concentrated W/0 emulsions (gel emulsions) showed that the equation proposed by Princen also holds for these systems. Measurements of the viscoelastic properties showed that these materials have a viscoelastic response that can be fitted to a Maxwell liquid element. The elastic and viscous terms of this model vary as a function of frequency as ... 

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