The object of this paper was to investigate extrusion foaming of different nanocomposites prepared with a linear polypropylene and chemically modified montmorillonite. A chemical blowing agent was used with dies of 2 mm diameter mounted in a single screw extruder. Although the filler loading was about the same in the two nanocomposites, the quality of the foam produced was quite different: one of them was all closed cell and had a more uniform cell size distribution. This nanocomposite had two distinct characteristics: the melt displayed strain hardening in uniaxial extensional flow while the other did not and its crystallization temperature was higher than that of the other nanocomposite.
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