Elastic modulus elastomeric networks

As is obvious from the above discussion, a very detailed understanding of entangling in elastomeric networks is required for interpretation of the elastic modulus, in particular its dependence on deformation and swelling. 

Linear Elastic and Rubber Elastic Behavior. Although stiffening is quite noticeable in the glassy regime of the amorphous phase, the most spectacular effect is seen in the rubber elastic regime phase, as already evoked in the case of reinforcement by cellulose whiskers (2). The PA6-clay hybrids example presented in Table 3 is quite representative of the situation encoimtered with semi crystalline thermoplastics, but elastomeric networks benefit as well of clay layer dispersion with a two- to threefold increase in modulus for polyurethane or epoxy networks... 

The mechanical properties of elastomeric networks are described within the theory of rubber elasticity, which accounts for the behavior of a network—in fact, its elastic modulus—as a function of its molecular parameters (number of elastic... 

The principle rheological properties which reflect the polymer process dynamics are the loss modulus (C), storage modulus (G"), dynamic complex viscosity (n ), and tan delta parameters. In simplified form the loss modulus describes the viscous or fluid component of viscosity. That is, how easily the molecules can move past each other. The storage modulus describes the elastic or network entanglement structure of the polymers. It is, therefore, sensitive to cross linking, reaction formation and the elastomeric modifiers. The complex dynamic viscosity is the combined effect of both moduli discussed. It, therefore. 

In order to complete our model, we need to know the soft phase modulus, Egp. It depends on several factors, most notably polyol equivalent weight. Eg, polyol functionality, fp, and polyol glass transition temperature, Tgp. At temperatm-es substantially above (elastomeric region), the modulus of the soft phase can be described using network elasticity models [57-59] ... 

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