Rheologica Acta

, Volume 49, Issue 3, pp 285–298 | Cite as

Interfacially active particles in droplet/matrix blends of model immiscible homopolymers: Particles can increase or decrease drop size

  • Prachi Thareja
  • Kevin Moritz
  • Sachin S. VelankarEmail author
Original Contribution


Particles have been shown to adsorb at the interface between immiscible homopolymer melts and to affect the morphology of blends of those homopolymers. We examined the effect of such interfacially active particles on the morphology of droplet/matrix blends of model immiscible homopolymers. Experiments were conducted on blends of polydimethylsiloxane and 1,4-polyisoprene blended in either a 20:80 or 80:20 weight ratio. The effects of three different particle types, fluoropolymer particles, iron particles, and iron oxyhydroxide particles, all at a loading of 0.5 vol.%, were examined by rheology and by direct flow visualization. Particles were found to significantly affect the strain recovery behavior of polymer blends, increasing or decreasing the ultimate recovery, slowing down or accelerating the recovery kinetics, and changing the dependence of these parameters on the applied stress prior to cessation of shear. These rheological observations were found to correlate reasonably well with particle-induced changes in drop size. The particles can both increase as well as decrease the drop size, depending on the particle type, as well as on which phase is continuous. The cases in which particles cause a decrease in drop size are analogous to the particle stabilization of “Pickering emulsions” well-known from the literature on oil/water systems. We hypothesize that cases in which particles increase drop size are analogous to the “bridging–dewetting” mechanism known in the aqueous foam literature.


Polymer blends Pickering emulsions Strain recovery Interfacial tension Compatibilizers 



We thank Rhodia Silicones and Kuraray America for providing the PDMS and PI homopolymers, respectively. We are grateful to Elementis Inc., Dyneon Corp., and Prof. Phule (University of Pittsburgh) for making particles available for this research. This research was supported by a CAREER grant CBET- 0448845 from the National Science Foundation, USA.


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Prachi Thareja
    • 1
  • Kevin Moritz
    • 1
  • Sachin S. Velankar
    • 1
    Email author
  1. 1.Department of Chemical EngineeringUniversity of PittsburghPittsburghUSA

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