The theory of coalescence in melts of polymer blends was derived on the basis of the Smoluchowski theory for colloid systems. An approximation for a flux of particles used for solutions of colloids in water was analyzed. It is shown that this approximation cannot be used for polymer blends, and an approximation is suggested that could be justifiably used for them. A system of equations was derived for the time dependence of the number of individual i‐mers, using the relation suggested for the diffusion flux of particles. In an approximation of the uniform increase in particle size, equations were found for the time dependence of the number of particles, the average radius of the particle, and the interface area in the volume unit of the blend. The suggested theory predicts measurable coalescence in considerably more viscous systems than mechanically applied relations of the Smoluchowski theory for aqueous colloid solutions.

The paper presents analysis of the phase structure development in polymer blends, where a minor component is dispersed in the matrix consisting of a major component, during the melt mixing, Problems of modelling of the flow field in mixing devices are briefly discussed. Relevant results of theoretical and experimental studies of the droplet breakup and coalescence are summarized. Theories dealing with the competition between droplet breakup and coalescence are discussed in detail. Their results are compared with experimentally determined dependences of the size of dispersed droplets on mixing conditions, properties of the components, and blend composition.

dynamischen Gleichgewichts zwischen dem Zerfallen und der Koaleszenz der Polymerpartikelchen interpretiert. Bei Elastomerkonzentrationen, die hOher als 15% liegen, korrelieren die Unterschiede zwischen der Schlagzahigkeit einzelner Polymermischungen mit der Partikelgr6Be des Modifizierungselastomeren. Eine Dispersion, deren Struktur noch feiner ist als die der mit optimalen Schlagztihigkeitseigenschaften, kann nur bei Verwendung von hochviskosen Polypropylenmatrizes hergestellt werden.

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The dynamic mechanical behavior of the binary blends high‐density polyethylene/EPDM rubber (ethylene‐propylene‐diene terpolymer) and isotactic polypropylene/EPDM rubber was investigated by means of a free‐oscillating torsional pendulum. Comparison of the moduli of the systems studied and predictions drawn from several models show that phase inversion in the polyethylene/EPDM blends takes place at the volume fraction vPE = 0.5, while polypropylene preserves a certain phase continuity also as the minor component (0.5 > vPP > 0.2) in blends with EPDM. Because of faster shrinkage in the course of cooling, inclusions are exposed to negative hydrostatic pressure, which accounts for a drop in the glass‐transition temperature of the rubber. The strength of the relaxation associated with the glass transition of inclusions and tensile impact strength increase proportionately to the rubber content in polypropylene (0 < vEPDM < 0.4). Dynamic mechanical response spectra of commercial EPDM/polyethylene impact modifiers are compared with the results for model systems.