General Properties of Bicontinuous Phase Nanocomposites

The most important characteristics of nanocomposites, which arise from the cocontinuity of the two phases, are as follows  

For the case of properties listed in (a) and (b) one notes that the phase cocontinuity produces conditions for which the strain in the two phases, resulting from an externally applied stress, is constant across the two phases and uniform through any cross section of the composites. 

In view of the continuity of the reinforcing inorganic phase, the global stress acting on the composite across this section is fairly close to the sum of the stresses on the two phases, weighted by the respective volume fractions, that is. 

For conditions in which the strains in the two phases are equal, Eq. (24.1) (law of mixtures) can also be written in terms of Young s modulus, E (see Chapter 2). The modulus obtained from the law of mixtures corresponds to the maximum value achievable in composite materials. 

Since the maximum stress that a material will withstand is synonymous with its strength, that is, the value of the stress at which fracture occurs, it can be stipulated that due to the isostrain conditions within the two phases, fracture in bicontinuous nanocomposites takes place when the most brittle phase, in this case the inorganic phase, reaches its ultimate strain value, E g.acture- When this condition is reached, fracture will rapidly propagate through the organic phase without any further increase in strain. Expressed in terms of fracture conditions Eq. (24.1), therefore, becomes 

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