Filler migration prediction

It is generally acknowledged that two distinct factors contribute to the final localization of the fillers thermodynamic effects, based on the affinity that the fillers might have with the polymers and kinetic effects that include the mode of preparation of the composites and the ability of the fillers to migrate to a different location, i.e., from one phase to the other or from one phase to the interface. These factors are critical in the prediction and control of filler localization and are described in detail below. 

Other than the thermodynamic effects, the mixing time can significantly affect the equilibrium location of filler in fact, the additional processing time can even lead to migration of filler particles from its equilibrium position as predicted from the surface energy analysis. Future work on polymer blends containing nanoparticles should combine the basic and applied research that has been done... 

Using data on the surface tension values of the rubbers and nanoclays used, the master curve of filler localization in 50/50 HNBR/NR and 50/50 HNBR/ ENR blends was calculated and is presented in Figure 6.24(a). A clay fraction of about 0.9 and 1.0 localized in the HNBR phase of HNBR/ENR and HNBR/ NR blends, respectively, was found, i.e. an almost complete localization of clay in the HNBR is predicted for both blends, when they reach a thermodynamic equilibrium state. Thus, at the beginning of the preparation of HNBR/ (NR-clay masterbatch) and HNBR/(ENR-clay masterbatch) blends, nanoclay pre-mixed in the NR and ENR phase is far away from its equilibrium state. Nanoclay is expected to migrate to the HNBR phase during the blending process. 

---