| Self-similar mixing microstructures of chaotic mixing were utilized to produce an array of morphological features in the blending of polyamide 6 and polypropylene.; A specially designed batch chaotic mixing device was built in-house to produce chaotic mixing under controlled conditions of temperature, initial segregation, and shear rate. Periodic waveforms applied to the rotor elements created non-linear perturbation to fluid element trajectories and produced chaotic mixing of polymers.; The effects of chaotic mixing parameter (&thetas;), shear gap of mixing chamber, waveforms, viscosity ratio and composition of the components, and in situ compatibilization on pathway of morphology development were studied. Poincaré maps, stretching distribution, and carbon black advection experiments were shown to be good tools to shed light on the effect of chaotic mixing on evolution of morphology.; Our results indicate that the PP-phase deformed into thin lamellas, which developed numerous perforations and underwent stretching to produce fibrils with aspect ratio as high as 10,000. The extended fibrils broke up into droplets due to capillary instability. A value of &thetas; = 1440° provided the best results, e.g., uniform mixing, faster generation of droplets, and smaller drop size with narrow size distribution. A mixing chamber with shear gap reduced by 25 percent provided better mixing at lower value of &thetas;. Also, a sine waveform produced better results than a square and a combination of steady and sine waveforms in terms of producing a narrower droplet size distribution. The square waveform produced higher effective stretching but caused premature breakup of extended fibrils in low shear zones and led to droplets with wider size distribution.; The results showed that the fastest rate of deformation of polypropylene-phase into layers, fibrils, and droplets occurred when the zero-shear viscosity ratio was 0.8. The drop size of the PP-phase increased about two fold in the viscosity ratio range of 0.8 to 30, as the concentration of the PP-phase was increased from 10 to 30 wt%.; Chaotic mixing conditions generated domain sizes much smaller than predicted by the balance between shear and interfacial forces and those obtained in the Brabender Plasticorder. More than 90% of the drops fell below the equilibrium size. |
