Effect of Reactive Blending on Phase Co-Continuity

The type of morphology which is formed during melt-blending depends on the material characteristics of the constituent polymers (interfacial tension, viscosity of the components and their ratio), their volume fiaction and mixing conditions. 

A lot of literature exists concerning the formation of co-continuous phase morphologies in uncompatibilized binary polymer blends. In general, the blend component with the lowest viscosity and highest volume fiaction forms the continuous phase, while the blend component with the highest viscosity and lowest volume faction forms the dispersed phase. The continuity of one phase within the other at low volume fractions depends on the 

Several relations have been proposed in literature by giving the volume fraction at which co-continuity can be formed as a fimction of the viscosity ratio. These include the relations proposed by Paul and Barlow [65], Jordhamo et al. [66], Metelkin and Blekht [67], and Utracki [68]. All these relations describe the phase inversion as a function of the viscosity ratio. It has been shown by Willemse et al. that the viscosity ratio alone is not sufficient to predict the phase inversion point in all cases [69]. Parameters such as the interfacial tension, the absolute values of the viscosities rather than their ratio, the phase dimensions, and the mixing conditions can have an important effect on the formation of continuous phase structures. Therefore, Willemse et al. proposed a new empirical model by introducing the dependence of the formation of the continuous morphology on material properties (matrix viscosity, interfacial tension) and processing conditions via the consideration of the shape of the dispersed phase required for achieving phase cocontinuity [69]. 

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