The Morphology of Multiphase Polymeric Materials

This complex morphology results primarily from spinodal decomposition within the rubber domains, although nucleation and growth kinetics are sometimes important. As described in Section 4.3.5, nucleation and growth results in spheroidal domains, while spinodal decomposition often results in interconnected cylinders. The actual morphology is not always obvious in thin section transmission electron microscopy. 

The rubber cellular domain structures are sometimes called salami structures, after their appearance. The toughness obtained in such materials is related to the rubber phase volume, which is the rubber volume plus the occluded polystyrene cellular domain volume. 

Phase inversion itself usually requires some type of shearing action on the polymers, or else metastable morphologies may result. During a polymerization the timing of the phase inversion is controlled by the volume fraction and the viscosity of each phase (18,19), 

The path of the ratio of the volume fractions to the inverse viscosity ratios in equation (13.12) may be tortuous in the polymerization of monomer 2 in the presence of polymer 1. As the polymerization of monomer 2 proceeds, the viscosity of both phases increases but not necessarily at the same rate. However, the volume fraction of the polymer-2 rich phase increases at the expense of the polymer-1 rich phase. 

Consider another case for the application of equation (13.12), this one involving the crosslinking of a polymer, which increases its viscosity. Blends of 

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