Rigidity modulus, definition

Adhesive systems can be divided into rigid, flexible structural and elastic bonding groups. A fourth group comprises sealants. These adhesive and sealant systems have a different, reversible elastic deformation and shear modulus (Fig. 6). Reversible elastic deformation is explained in more detail in the Glossary/ Definition of Terms at the end of this chapter. 

Elastic modulus is a quantitative measure of the stiffness or rigidity of a material. For example, for homogeneous isotropic substances in tension, the strain (e) is related to the applied stress (o) by the equation E = o/e, where E is defined as the elastic modulus. A similar definition of shear modulus (g) applies when the strain is shear. 

For example, in Chapter 6, to begin with three parameters, p (shear stress), e (shear strain), and E (modulus or rigidity), are introduced to define viscosity and viscoelasticity. With respect to viscosity, after the definition of Newtonian viscosity is given, a detailed description of the capillary viscometer to measure the quantity t follows. Theories that interpret viscosity behavior are then presented in three different categories. The first category is concerned with the treatment of experimental data. This includes the Mark-Houwink equation, which is used to calculate the molecular weight, the Flory-Fox equation, which is used to estimate thermodynamic quantities, and the Stockmayer-Fixman equation, which is used to... 

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