Effect of Nano-clay on Rheological and Extrusion Foaming Process of a Block-Copolymerized Polypropylene

The effects of nano-clay and the corresponding coupling agent maleic anhydride grafted polypropylene (PP-g-MAH) on thermal properties, rheological properties and extrusion foaming process of a block-copolymerized polypropylene (B-PP) were studied. Supercritical CO 2 (SC CO 2 ) was used as the foaming agent with a concentration of 5wt%. Each step of foamed B-PP/ PP-g-MAH/ nano-clay composites processing is addressed, including mixing of the composites, manufacture of the composites, foaming process of the composites and characterization of the cell structure. The results showed that incorporation of nano-clay and PP-g-MAH caused reduced melt strength and complex viscosity of B-PP. However, the heterogeneous nucleation induced by nano-clay and PP-g-MAH improved the maximum foaming expansion ratio and cell-population density of B-PP foam.