The reinforced HDPE/PA66 in situ fiberized composites were prepared by extrusion-drawing injection method. The influence of PA66 mass content(cm) on the PA66 fiberization, tensile strength(σt) and Young’s modulus(E) of the composites, together with their functional mechanisms were studied in contrast to the normal blended materials without drawing. The results showed that as cm rises from 0 to 25%, the number of PA66 fibers in-situ formed increases whereas their cross size and dispercity decrease till cm =15% and then increase. The σt and E of in-situ composites increase 45% and 60%,respectively,relative to neat HDPE at cm=15%. The fiberization of PA66 droplets through coalescence-deformation during melt-drawing plays a key role in the above variation of PA66 phase morphology with cm. The counterbalanced function between the reinforcing effect of dispersed phase on matrix and the interfacial flaw effect of the two phase and the rigidizing effect of fiber on matrix controlled by morphology of dispersed phase, are dominant factors of deciding the above σt ~ cm and E ~ cm relations, respectively.
