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In this work, microcellular ABS foams were studied. A series of injection molding samples defined by a design of experiments was carried out to analyze the effect of shot volume, mold temperature, and injection velocity on the morphology, mechanical properties, and surface roughness of microcellular samples. A predominant influence of shot volume on the cell structure and tensile properties was evidenced. Higher cell densities and narrower cell size distributions were obtained at lower injection volume. However, elastic modulus and tensile strength were improved by increasing the shot size. The effect of mold temperature and injection velocity was secondary. Higher levels of mold temperature and injection rate provided finer cell morphologies, but their effects on the elastic modulus and tensile strength were negligible. The decrease in shot volume and increase in gas content led to poor surface quality, whereas it was greatly improved by raising both mold temperature and injection velocityPostprint (author's final draft

In this work, the properties of microcellular ABS were studied. Foamed samples exhibited a solid skin/foamed core structure, with some elongated cells in the flow direction, while spherical cells were mostly observed in the transversal direction. The flexural modulus, flexural strength, and fracture toughness K Ic decreased with the density. However, the crack tip opening displacement (CTOD) was found to increase with the foaming ratio. The evolution of the mechanical properties and fracture toughness was well described by prediction models considering the skin/core morphology of these microcellular materials. Foaming increased the anisotropic behavior of the material, due to the cell elongation caused by the fountain flow during injection. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43010.