Studies on toughening effect of ultra-fine PA6 particles upon PP system

A novel technique to optimize the morphology and thus to enhance the mechanical properties of polypropylene(PP)/polyamide 6 (PA6) system was reported in this paper. Through pan-milling at ambient temperature, PP/PA6 pellets of particle size 2 similar to 5mm can be effectively pulverized down to well mixed micro-meter or even to nano-meter scale powders. By press molding the obtained ultra-fine PP/PA6 powder at a temperature between the melt points of PA6 and PP(say, 200 degreesC), a ultra-fine PA6 particle filled PP blend can be obtained, in which PP is the matrix,and PA6 powders maintain at solid state and are dispersed in PP matrix at micrometer scale. Morphological analysis shows that the domain size of PA6 in the system is much smaller than that of PP/PA6 blend and is similar to that of PP/PA6 blend compatibilized by PP-g-MAH. The mechanical properties of the system is much better than those of the PP/PA6 blend. The tensile strength of the ultra-fine PA6 particle filled PP/PA6 (70/30) blend is 29.3MPa, which is 6.1MPa higher than that of the PP/PA6 blend. Izod notched impact strength of the ultra-fine PA6 particle filled PP/PA6 (70/30) blend is 6.34kJ/m(2),which is 1.72kJ/m(2) higher than that of the PP/PA6 blend. These properties are comparable with those of the PP-g-MAH compatibilized PP/PA6 blend, i.e., pan-milling has the similar compatibilizing effect on PP/PA6 systems as that of incorporating a compatibilizer.