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Understanding morphological changes in polymer blends in the initial melting region of an extruder is crucial for optimizing the polymer mixing process. In blends with a large difference in their softening temperatures, a processing‐phase inversion transition occurs when a larger volume‐fraction of the higher melting component is present. The morphological changes in 80/20 PVDF/PS blends were examined (where PVDF forms the major phase) in an internal mixer under different processing conditions, such as preset temperature program, fill volume and rotor speed. We studied the torque behavior, energy consumption during mixing and phase inversion point for both 80/20 PVDF/PS and 80/20 PP/PS blends. PP needed 2.4 times higher mechanical energy to be deformed and to achieve a similar phase inverted state, compared to PVDF. To examine the effect of the minor phase properties, two 80/20 PVDF/minor ph.ase systems were examined: (i) a low‐melting viscous EVA (ethylene vinyl acetate copolymer), and (ii) a low viscosity PCL (polycaprolactone). Using a range of techniques, such as torque monitoring, optical microscopy, SEM etc., it is established that the nature of the minor phase (amorphous vs. semicrystalline), minor phase melt viscosity and the exact processing parameters influence the point at which the phase inversion occurs. [ABSTRACT FROM AUTHOR]

The vulcanization behavior and mechanical properties of clay/fluoroelastomer nanocomposites produced by melt-mixing of Dyneon FPO 3741 (a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene) with 10 phr of unmodified montmorillonite (CloisiteNA) or di(hydrogenated tallow-alkyl) dimethyl ammonium-modified montmorillonites (Cloisite15A and Cloisite20A) were studied. The properties of clay/FKM nanocomposites were compared with composites prepared using 10 and 30 phr of carbon black. The effects of clay surfactant and surfactant concentration on the vulcanization behavior, mechanical, and dynamical properties of peroxide cured composites were studied. XRD results of cured composites showed a decrease in d-spacing and indicated deintercalation of the clays after the vulcanization process. It was also found that organoclays retard the FKM peroxide vulcanization process. Significantly, higher maximum torque on vulcanization was obtained with organoclays versus unmodified clay and carbon black. Although the morphologies of organoclay/FKM nanocomposites studied by XRD and TEM suggest similar intercalated/exfoliated structures, the organoclay with the lowest concentration of surfactant (95 meq/100 g clay) resulted in the highest increase in torque, modulus, hardness, and tear strength in the clay/FKM nanocomposites. It was also found that organoclays can increase both the hydrodynamic reinforcement and hysteresis loss of FKM nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]