Mechanical Property and Microcellular Foamability of iPP/PA11/PP-g-MAH Blends

To improve the mechanical property and foamability of linear structured isotactic polypropylene (iPP), a second phase of polyamide11 (PA11) was introduced to the iPP matrix, and a low contented PP-g-MAH was added to adjust their compatibility. As a result, a high impact strength of 8.43 kJ/m² (a 118% increase compared to that of iPP) and an elongation at break of 465.87% (a 130% increase compared to that of iPP) of the compounded iPP/20PA11/10PP-g-MAH were achieved, which was attributed to the PA11 being well distributed in the iPP matrix and to the compatibility enhancement by PP-g-MAH. Depending on a suitable material formulation and a bath foaming strategic design, microcellular cells with an average size from 204.8 to 5.9 μm and a cell density from 6.0 × 10⁶ to 6.5 × 10⁹ cells/cm³ were obtained. Due to the significant enhancement of melt strength by partially melted crystals, combined with the synergistic effect of PA11, a quiet high expansion ratio of up to 37.9 was achieved. These manufactured foams have potential applications in packaging, thermal insulation, and other industrial fields.