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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

This article is dedicated to the study of the thermal parameters of composite materials. A nonlinear least-squares criterion is used on experimental transfer functions to identify the thermal conductivity and the diffusivity of aluminum-polymer composite materials. The density measurements were achieved to deduce the specific heat and thereafter they were compared to values given by differential scanning calorimetry measurement. The thermal parameters of the composite material polypropylene/aluminum were investigated for the two different types of aluminum filler sizes. The experimental data were compared with several theoretical thermal conductivity prediction models. It was found that both the Agari and Bruggeman models provide a good estimation for thermal conductivity. The experimental values of both thermal conductivity and diffusivity have shown a better heat transport for the composite filled with large particles.

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