Analysis of Morphology Formation in Elastomer Blends

Abstract

Based on the assumption that an equilibrium particle size of dispersed phase will be reached when the breaking-down rate and the coalescence rate are balanced, a theoretical expression was obtained. The theory showed qualitatively that the equilibrium particle size becomes smaller when (1) the stress field is increased, (2) the interfacial tension between matrix and dispersed phase becomes smaller, and (3) the concentration of dispersed phase decreases. Qualitative verification of the theory was obtained by experimental examination of the NR-EPM blend system. In practice, in order to obtain a small particle size in a short time at above 20% volume fraction, the matching of rheological properties of the matrix and the dispersed phase is desirable. On changing from internal mixer to mill, the temperature became one of the most influential factors that control the particle size. Future work, such as the quantitative value of interfacial tension as a function of temperature, and macroscopic breaking energy measurement, etc., is necessary to confirm the theory quantitatively.

Interactions, structure and properties in poly(lactic acid)/thermoplastic polymer blends

“…It is known, though, that the size of dispersed particles depends, among others, on interfacial tension which can be related to the Flory-Huggins interaction parameter [60,62,64,76]. The relationship of these parameters is supported also by the results presented above and the data of Table 1.…”

“…The size of dispersed particles decreases as a function of mixing time until an equilibrium is reached between break-up and coalescence [61]. Several different models aim to describe the factors affecting this process and the final morphology [61][62][63][64][65][66][67]. According to them, equilibrium particle size is assumed to depend on numerous factors including composition, shear rate, the relative viscosity and interfacial tension of the components, degradation, energy required for particle break-up, coalescence probability, etc.…”

Mixing of viscous immiscible liquids. Part 1: Computational models for strong–weak and continuous flow systems

“…Two sets of experimental data (Tokita, 1976;Favis & Chalifoux, 1988) displaying this trend are shown in Fig. 14.…”

“…Fig. 9 shows three sets of experimental data obtained from the literature corresponding to a polymer blend produced in a Banbury mixer (Favis & Chalifoux, 1987;Schreiber & Olguin, 1983;Tokita, 1976). As is standard practice we plot the average size of the dispersed phase versus viscosity ratio.…”

Thermal and rheological behavior of reactive blends from metallocene olefin elastomers and polypropylene

“…In order to guarantee blend homogeneity it is crucial to attain good interaction at interface and stabilization of morphology during processing [32] . Among the important parameters for droplet formation and breakup in viscoelastic fluids are viscosity and elasticity ratios, interfacial tension, blend composition and type of flow [33] . An extensional flow field as present in an internal mixer is believed to be more effective for tread formation and breakup, moreover a broader viscosity ratio can be used and still lead to small particle size [34] .…”