Effect of composition on phase morphology and mechanical properties of PP/PA66 in situ composites via extrusion-drawing-injection method

The reinforced and toughened PP/PA66 in situ composites were prepared via extrusion-drawing-injection method. The relationship among composition, phase morphology and mechanical properties, together with their functional mechanism, was investigated. The results show that in the range of PA66 weight fraction (f _w) from 0 to 20% and under the experimental processing conditions, the main changes in phase morphology of the composites with f _w are that the number of in situ formed PA66 microfibers and remained PA66 particles increases with f _w whereas the fiber transverse size and its dispersity decrease till f _w = 15% and then increase. This can be attributed to the combined effect of break-up, coalescence and deformation of the PA66 phase in the PP phase in the course of extrusion and drawing. The tensile strength of composites has a maximum value at f _w of 15% and Young's modulus increases with f _w up to a plateau level, while impact strength continuously rises with f _w, an effect which can be ascribed to the distinct dependence of these properties on the phase-morphological factors mentioned above.