Among Various Viscoelastic Properties

This result clearly shows that (unlike an elastic material) the relaxation modulus and the creep compliance are not reciprocals. That is. 

In cases where the rate of change of strain or stress is very small, the creep compliance and relaxation modulus may be approximately the inverse of each other. Consideration of simple Maxwell and Kelvin models confirm the condition given by Eq. 6.42 as in Homework problem 6.7. 

In Chapter 5, using Alfrey s correspondence principal for a generalized mechanical model it was found that the stress and strain could be related in Laplace transform space as 

Note also that while reciprocity of the modulus/compliance is not valid in the time domain (Eq. 6.42), it is valid in the transform domain 

Expressions analogous to Eq. 6.43 were developed in Chapter 5 using a 

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Among various dynamical properties of polymeric liquids, an important and conspicuous property is their medianics. As one knows in everyday life, polymeric liquids (chewing gum, dough, or egg white, for example) show quite distinct flow behaviours from the usual liquids like water a polymeric liquid is usually quite viscous and has visible elasticity. For example if one stretches chewing gum and releases it quickly, then it will shrink like rubber, yet chewing gum is a liquid and can fill a container of any shape. Tliis property, called the viscoelasticity, is just one of the many distinctive properties of polymeric liquids. The purpose of this book is to understand such properties from the molecular point of view. 

In this book, we review the most basic distinctions and similarities among the rheological (or flow) properties of various complex fluids. We focus especially on their linear viscoelastic behavior, as measured by the frequency-dependent storage and loss moduli G and G" (see Section 1.3.1.4), and on the flow curve— that is, the relationship between the "shear viscosity q and the shear rate y. The storage and loss moduli reveal the mechanical properties of the material at rest, while the flow curve shows how the material changes in response to continuous deformation. A measurement of G and G" is often the most useful way of mechanically characterizing a complex material, while the flow curve q(y ) shows how readily the material can be processed, or shaped into a useful product. The... 

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