Blending dispersive mixing

Surface tension plays a significant role in the deformation of polymers during flow, especially in dispersive mixing of polymer blends. Surface tension, as, between two materials appears as a result of different intermolecular interactions. In a liquid-liquid system, surface tension manifests itself as a force that tends to maintain the surface between the two materials to a minimum. Thus, the equilibrium shape of a droplet inside a matrix, which is at rest, is a sphere. When three phases touch, such as liquid, gas, and solid, we get different contact angles depending on the surface tension between the three phases. 

These experimental mixers enabled the study of the role of the rheological properties of the individual blend components on the mechanisms and rates of dispersive mixing. Three commercial polymers Dow Chemical Company polystyrene (PS686) and low density polyethylene (PE 132) and Chevron low density polyethylene (PE 1409) were used in the study. Figure 11.32 (a) shows the viscosities of the three polymers at 200°C (121). PS 685... 

Fig. 11.34 The dispersive mixing mechanism of the equiviscous Blend 2 at 180°C and 120rpm. Repeated stretching and folding is evident, which result in sheets that have holes, ligaments, and droplets. [Reprinted with permission from Proceedings of the Eighth Semi-annual Meeting of the Polymer Mixing Study, Polymer Processing Institute, Hoboken, NJ (1994).]...

Fig. 11.39 Melt-melt dispersive mixing Blend 2 in the TSMEE at 140°C and 120 rpm. [Reprinted...

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