Analysis of the Phase Structure Development during the Melt Mixing of Polymer Blends

Abstract

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.

Polymer Blends

“…well understood qualitatively for binary polymer blends with dispersed structure. It is broadly accepted that the size of dispersed droplets in flowing blends is controlled by the competition between the droplet breakup and coalescence (70,(90)(91)(92)(93)(94). On the other hand, the droplet breakup and coalescence in blends with viscoelastic components are complex events only approximately described.…”

“…On the other hand, the droplet breakup and coalescence in blends with viscoelastic components are complex events only approximately described. Moreover, the flow field in mixing devices is also complex, which further complicates correct description of the phase structure development (70,(92)(93)(94). Deformation of a droplet in a flow field is controlled by the competition of the deforming stress, t, setting on the droplet by external flow field and the shape conserving interfacial stress, s/R, where R is the droplet radius (70,(90)(91)(92)(93)(94)(95)(96).…”

“…For flow in mixing devices, the dependence of Ca c on p lies between those for shear and extensional flow (94). Two main breakup mechanisms were recognized: stepwise, ie, a repeated droplet breakup into two fragments; and transient, where the droplet is stretched into a long fiber that bursts into a chain of small droplets (70,90,(92)(93)(94)97). It seems that the stepwise mechanism operates for Ca only slightly higher than Ca c and the transient mechanism for Ca > > Ca c .…”

Morphology of PC/SAN blends: effect of reactive compatibilization, SAN concentration, processing, and viscosity ratio

“…The competing processes of drop break-up and coalescence during melt processing determine the final morphology of these mixtures. 5,6,[23][24][25][26][27][28][29][30][31] Morphology Development…”

Morphology Development of Polymer Blends in Extruder: The Effects of Compatibilization and Rotation Rate

“…[2] It is believed that the early mixing stage is controlled by breakup, and the final stage is dominated by the balance between drop breakup and coalescence. [27,[36][37][38][39] Besides this general observation, the effects of polymer compositions, viscosity ratio, processing time or temperature, and shear rate on morphology evolution of polymer blends have also been investigated. [27,[40][41][42][43] Compatibilization is a common method used to improve the mixing of polymer blends and control the morphology.…”