Thermal conductive materials based on flake graphite-filled Polyamide 6 (PA6) and Polyamide 6/Polycarbonate (PA6/PC) immiscible blend with a mass proportion of 7/3 were prepared by twin screw extruding. At the graphite loading of 40 wt% (25.42 vol%), thermal conductivity of PA6/PC/graphite composite reached to 2.716 W/mK, which is 30.3% higher than that of mono-PA6/graphite composite. SEM images showed that graphite began to form thermal conductive network at 30 wt% (17.97 vol%), and mainly dispersed in PA6 phase, corresponding to the fast growth of thermal and electrical conductivity of the composites after such certain filling. The melt rheology analysis further confirmed the filler concentration for conductive network formation of graphite. Based on DSC data, the introduction of PC phase and graphite had little effect on the melting behavior of the composites, but a prominent heterogeneous nucleation effect and greatly accelerated its crystallization procedure of PA6. (C) 2013 Elsevier B.V. All rights reserved.