Combined effect of organic phosphate sodium and nanoclay on the mechanical properties and crystallization behavior of isotactic polypropylene

摘要

Combined effect of α-nucleating agent (NA) sodium 2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate (NA11) and nanoclay (NC) on the mechanical properties and crystallization behavior of isotactic polypropylene (iPP) was investigated by mechanical testing, wide-angle X-ray scattering (WAXD), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and scanning electron microscopy (SEM). The mechanical testing results indicated that the separate addition of NA11 and NC only increased the stiffness of iPP while the combined addition of NA11, NC, and maleic anhydride grafted polypropylene (PP-g-MA) simultaneously improved stiffness and toughness of iPP. Compared to pure iPP, the tensile strength, the flexural modulus, and impact strength of iPP composites increased 9.7, 38.6, and 42.9, respectively. The result indicated good synergistic effects of NC, NA11, and PP-g-MA in improving iPP mechanical properties. WAXD patterns revealed NA11, and NC only induced the α-crystals of iPP. SEM micrograph showed that the PP-g-MA could effectively improve the dispersing of NC in iPP. Finally, the nonisothermal crystallization kinetics of neat iPP and PP nanocomposites was described by Caze method. The result indicated that the addition of NA overcame the shortcoming of low crystallization rate of NC nanocomposites and maintained the excellent mechanical properties, which is another highlight of the combined addition of NAs and nanoclay. Meanwhile, the result showed that nuclei formation and spherulite growth of iPP were affected by the presence of NA and nanoclay.