Migration of nanosilica particles in polymer blends

Abstract

Hydrophilic pyrogenic silica melt mixed in immiscible polypropylene/poly (ethylene‐co‐vinyl acetate) (PP/EVA) blend was found to migrate from the PP matrix to the EVA dispersed domains and remained confined inside them. Surprisingly, it was shown than silica was also able to migrate from a dispersed PP phase to an EVA matrix but this transfer was slower and not complete. The same silica with a hydrophobic surface treatment moved and accumulated to the blend interface and in PP. The mechanisms from which this migration proceeds are discussed. Whereas self diffusion of the particles was shown to have almost no effect, shear induced movements and collisions with dispersed drops is believed to be the most efficient mechanism. The possible trapping of silica aggregates during droplet–droplet coalescence was impossible to observe but is thought to be a possible additional mechanism. No quantification on the relative importance of the latter phenomenon can be drawn at the moment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1976–1983, 2008

Tuning the processability, morphology and biodegradability of clay incorporated PLA/LLDPE blends via selective localization of nanoclay induced by melt mixing sequence

“…The migration of nanoclays from the matrix to the dispersed phase takes place more easily than from dispersed droplet to the matrix. However it is quite evident that migration of nanoclays from the matrix to the dispersed phase is not the only possible migration type [25]. It is interesting to underline that in spite of higher affinity between LLDPE and 15A, no localization of this organoclay within LLDPE phase is observed in any sample obtained by different mixing methods.…”

“…In this context addition of compatibilizer to a clay-containing multiphase system can have its own contribution towards clay positioning and its state of dispersion due to induced changes in the system thermodynamic. This topic has been discussed intensively in the literature [19][20][21][22][23][24][25][26][27][28][29]. Undoubtedly, the mixing procedure has also a strong effect on the localization of nanoclay.…”

Role of nanosilica localization on morphology development of HDPE/PS/PMMA immiscible ternary blends

“…This stems from the fact that the addition of nanofiller into immiscible polymer blends has proved to be an efficient method to develop a new family of polymer nanocomposites with a great tailoring potential for producing products with combination of prescribed properties. In this context the localization of nanoparticles has been found to play an important role in determining the resulting morphologies of polymer blends [11][12][13][14][15][16][17][18][19][20][21]. This is why a considerable number of studies have been directed toward understanding parameters controlling the nanoparticle localization in polymer blends.…”

“…Hence they can form a network of connected or interacting particles in the molten polymer [25,26]. Elias and coworkers [15,16] studied the effect of two types of nanosilica (Hydrophobic and hydrophilic silica) on the morphology of polypropylene/ poly (ethylene-covinyl acetate) PP/EVA immiscible blends and their possible migration towards more favorable phase. A significant reduction in the EVA droplets size was observed for both types of silica-filled samples which was mainly attributed to compatibilizing effect of nanofiller.…”

Tuning the nano/micro‐structure and properties of melt‐processed ternary composites of polypropylene/ethylene vinyl acetate blend and nanoclay: The influence of kinetic and thermodynamic parameters

“…The subsequent morphological analysis showed uniform dispersion of the EVA compatibilizer and the organoclay in the main PP phase, producing intercalated composites. A significant amount of work has been published on PP/EVA/nanoclay composites, [16][17][18][19][20][21][22][23] migration of fillers, and mixing sequences in ternary polymer blend composites 24 ; however, to the best of our knowledge, only one study 23 has explored how organoclay incorporation affects the blend morphology and the spatial distribution of the nanoclay, and how these factors in turn affect the mechanical properties. The authors of this study 23 only focused on the effect of the blending sequence on the morphology and properties of ternary nanocomposites using a twin-screw extruder, but did not investigate the kinetics of nanoclay migration in composites, the kinetics of microstructure formation, or the relation between microstructural differences and the properties of the nanocomposites.…”