Gels equilibrium elastic shear modulus

A typical evolution of equilibrium mechanical properties during reaction is shown in Fig. 6.1. The initial reactive system has a steady shear viscosity that grows with reaction time as the mass-average molar mass, Mw, increases and it reaches to infinity at the gel point. Elastic properties, characterized by nonzero values of the equilibrium modulus, appear beyond the gel point. These quantities describe only either the liquid (pregel) or the solid (postgel) state of the material. Determination of the gel point requires extrapolation of viscosity to infinity or of the equilibrium modulus to zero. 

According to the theory of rubber elasticity [29], the "equilibrium" shear modulus Ge°(T), above Tg, of a polymer crosslinked beyond its gel point, is determined by Mc. Equation 11.22... 

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