The ultrasonic disintegration behavior of polystyrene-block-poly(ethylene-co-butylenes)-block-polystyrene (SEBS) in polypropylene (PP) melts was studied by means of scanning electron microscopy (SEM) and dynamic rheological measurements. A disintegration kinetics model of the dispersed phase in polymer matrix was proposed to explain the ultrasonic disintegration kinetics, and it is in accordance with the equation: d(t) = d infinity +d(0)-d infinity/1+K-t. The experimental results showed that the average particle diameter of SEBS decreased with sonication time and approached a limiting value (the equilibrium diameter), below which no further disintegration occurred. The effects of ultrasonic power, ultrasonic frequency, sonication distances, and heating temperatures on the morphology of PP/SEBS blends were also investigated. SEM results demonstrated that the increase of ultrasonic power could enhance the dispersion of SEBS. And SEBS particles were more easily disintegrated at 20 kHz. Moreover, the disintegration extent decreased with the increase of sonication distance or melt temperature. The dispersion state of SEBS was indirectly evaluated by the dynamic rheological properties. It was found that there was an increase in the complex viscosity, storage, and loss moduli as the ultrasonic intensity was in an appropriate scope. (C) 2016 Wiley Periodicals, Inc.
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