Magnesium hydroxide—filled polypropylene foams were prepared by a compression-molding chemical foaming process and studied considering the effects of foaming and the presence of the particles on the microstructure (cellular structure and induced particle and polymer orientations), dynamic mechanical, and flame retardancy of the polypropylene composites. Two magnesium hydroxide concentrations, 50 and 70 wt%, as well as different foam densities, were considered. Results are discussed in terms of the observed anisotropy-induced cellular and particle and crystal orientations and their effects on the direction-dependent dynamic mechanical and flame behavior results. Preliminary flame retardancy characterization of the several solid and foamed composites showed interesting results due to foaming, foams globally exhibiting a higher extinguishability than the respective solid composites.

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