Stability of Blend Morphology

In order to decrease the interfacial area in blends with a dispersed morphology, two approaches are possible. The first approach involves a shape relaxation of the deformed particles that may occur as the latter tend to acquire a spherical shape. Nevertheless, highly stretched particles can simultaneously undergo further breakups after the cessation of flow, and this process is concurrent to shape relaxation [99]. A second approach to reducing the total surface energy of the system is for the droplets to become fused this will lead to a coarsening of the blend s phase structure. 

Coalescence in quiescent blends containing spherical dispersed droplets can be induced by interdroplet molecular forces, namely van der Waals forces and/ or Brownian motion. An approximate theory of the molecular forces and Brownian motion-driven coalescence was derived [107] which considers the interaction of a droplet only with its nearest neighbor. Furthermore, it considers the system as monodispersed, and also treats the Brownian motion in a very approximate manner. The theory was derived for Newtonian droplets in a Newtonian matrix, and for Newtonian droplets in a viscoelastic matrix described by the Maxwell model. Coalescence in viscoelastic matrix was shown to be more rapid than in the Newtonian matrix with the same viscosity. 

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PBT/HDPE PBT 1 to 90 wt% Nanofil 919 PBT phase and interface based on blend composition The MMT particles located at the blend interface reduce the interfacial tension between blend components. The addition of organoclay also increases the thermal stabilization of blend morphology Hong et al. 2006a, b... 

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