Microcellular PP-CaCO3 Nanocomposites: Relationship Between Nanocomposite Morphology and Foam Morphology

Abstract

Polymeric nanocomposites exhibit high potential as a new material for carbon dioxide (CO2) foaming. In this paper, a polypropylene (PP)/nano-calcium carbonate (nano-CaCO3) composite was selected to investigate the relationship between nanocomposite morphology and foam morphology. Nanocomposites were prepared using a twin-screw extruder with screw including both shearing and mixing elements. Nanocomposites with different morphology via changing the nano-CaCO3 content were then foamed by using supercritical CO2 in a batch system. Effect of nano-CaCO3 content on the volume expansion ratio, and cell coalescence were studied.

Improving of Cell Structure of Microcellular Foams Based on Polypropylene/High-density Polyethylene Blends

“…The aforementioned results may be explained as follows. First, the nanoparticles dispersed in the PP and HDPE phases (as shown in Figure 5) play a role as heterogeneous nucleating agents [10,16,17], thus providing more sites for cell nucleation. Especially in exfoliated claybased nanocomposites and well-dispersed CaCO 3 -based nanocomposites, the nanoparticles with their extremely fine dimensions provide a much larger interfacial area between particles and polymer matrix to facilitate the cell nucleation.…”

“…The visual observation by Taki et al [8] showed that the nanoclay can improve the cellular structure of foamed PP by enhancing the nucleation and retarding the growth of bubbles in the early stage of foaming. Very recently, using a pressure vessel as the foaming apparatus, Huang and Wang [9,10] improved the foamability of PP by blending it with HDPEs and incorporating the nano-calcium carbonate (nano-CaCO 3 ) particles into it and its blends with HDPE.…”