Deagglomeration-reagglomeration

Kraus model of deagglomeration-reagglomeration of filler aggregates, assimilated to "soft spheres."... 

A5.2 Kraus Deagglomeration-Reagglomeration Model for Dynamic Strain Softening... 

Dynamic modulus varies with strain because of a deagglomeration-reagglomeration process of soft spheres. 

Improved mineral dispersion and wet out by the matrix resin leading to mineral deagglomeration and resistance to reagglomeration. 

To account for the strain-dependence of the dynamic moduli, Kraus considered that, at equilibrium the rates of aggregate deagglomeration and reagglomeration are equal and assumed that power law functions account for the strain dependency, i.e. ... 

As previously commented, the postulate considered by Kraus (i.e.. Equation 5.34) imparts symmetries in both the G (Yo) and the G"(Yo) functions. If indeed, experimental data support an horizontal symmetry for the elastic modulus, with respect to the mid modulus value, no vertical symmetry (with respect to y<) is generally observed for the viscous modulus. The deficiencies of the Kraus model are therefore, embedded in the starting postulate. Various modifications have been proposed to account for the nonsymmetri-cal behavior of G" without changing the physical ideas leading to the model. Using different strain exponents for the deagglomeration and reagglomeration processes (Equation 5.34) was probed by Ulmer who concluded that it... 

At equilibrium the rates of aggregate deagglomeration and reagglomeration are equal, i.e. ... 

Gv =G" maximum value of viscous modulus (occur-ing at the critical strain) m=exponent related to the rates of deagglomeration and reagglomeration of filler particles... 

---