In this study, flake graphite was dispersed in immiscible polyamide 6/polypropylene (PA6/PP) blends to improve their thermal conductivity. Blends of PA6/PP were prepared in different relative fractions and thermal conductivity of the graphite-containing blends showed enhanced values for immiscible blends when compared with those of mono-PA6-based composites at the same graphite loading fractions. Moreover, a PA6/PP mass ratio of 8/2 showed better dispersion of graphite and less interfacial defects, resulting in better heat conduction ability when compared with other immiscible blends. At graphite loading of 40 wt%, thermal conductivity of PA6/PP/graphite composite reached 2.896 W/mK, which is nearly 40% higher than that of mono-PA6/graphite composite. Morphology and melt rheology measurements confirmed that flake graphite began to form thermally conductive network at 30 wt% in immiscible blends which is crucial to the improvement of thermal conductivity.
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