Improved cell nucleating effect of partially melted crystal structure to enhance the microcellular foaming and impact properties of isotactic polypropylene

The effects of a partially melted crystal structure (PMCS) on enhancing the cell nucleating behavior, as well as on the related foaming behavior of isotactic polypropylene (iPP), were investigated. The incorporation of PMCS and the corresponding effects were characterized by rheological, thermal and X-ray testing methods. The microcellular foaming results revealed that the addition of PMCS could dramatically increase the melt strength and the cell nucleating sites of the matrix. The synergistic effects of the PMCS and high melt strength polypropylene (HMSPP) could decrease the average cell size to approximately 2 mu m and increase the cell density to 1.49x10(11) cells/cm(3). Additionally, the gradual melting of the PMCS could also prove its enhancing effect on the melt strength and cell nucleating ability. The uniform microcellular cells obtained could positively affect the notched impact strength of the foamed iPP-HMSPP blends. (C) 2020 Elsevier B.V. All rights reserved.