Theoretical description of steady droplet size in polymer blends containing a compatibilizer

A theory was derived which describes the dependence of the size of disperse d droplets on the composition of compatibilized polymer blends in steady sh ear flow. The effect of droplets breakup and coalescence on the interfacial area available for molecules of a compatibilizer and, hence, on interfacia l tension has been considered. Dependences of the droplet size on the volum e fraction of the dispersed phase has been determined for the following cas es: (i) constant density of a compatibilizer on the interface; (ii) all com patibilizer molecules are localized on thr interface; (iii) maximum density of a compatibilizer on the interface exists which is characteristic of the system under study. The shapes of the dependences of the droplet size on t he amount of dispersed phase for these cases are different. They strongly d ifferentiate if the total amount of a compatibilizer or the ratio of the am ount of compatibilizer to that of dispersed phase is constant during an inc rease in volume fraction of the dispersed phase. (C) 2000 Elsevier Science Ltd. All rights reserved.