Morphology and mechanical characterization of ABS foamed by microcellular injection molding

Abstract

In the present work ABS was used to inject cylindrical test bars, obtaining solid and foamed specimens. By varying the gas content, two levels of weight reduction were achieved. Morphology analysis revealed the presence of solid skin-foamed core structure in foamed samples. SEM micrographs showed a nucleus zone having bigger cells and irregular cell distribution, surrounded by a microcellular area with finer cell structure. Foamed bars with 10% and 17% of weight reduction presented similar values of cell size, cell density and solid skin thickness. On the other hand, results provided by simulation software were consistent with the experimental analysis. Mechanical properties were determined through tensile tests. Tensile strength and elastic modulus gradually decreased with decreasing apparent density. Experimental results were related to relative density and morphology parameters, and prediction models were employed to compare the estimated values to the experimental data.