Highly thermally conducting polyamide 6 (PA6) composites with high loadings of low-temperature expandable graphite (LTEG) were prepared by an in situ exfoliation melting process, and the thermal conductivity of the composites was measured by a hot-disk method. A two-point method was applied to evaluate the electrical conductivity of the composites with various graphite loadings, and the thermal percolation was observed in the vicinity of the electrical percolation threshold concentration. Dynamic rheology analysis was used to define the geometric change caused by the interconnection of the in situ exfoliated graphite flakes. X-ray diffraction measurement confirmed that the exfoliation of LTEG was crucial to the overall thermal conductivity of the composites. Dynamic mechanical analysis revealed that the incorporation of LTEG significantly improved the damping properties of PA6. Thermogravimetric analysis and differential scanning calorimetry measurements were applied to study the thermal properties of the investigated PA6/LTEG composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39596.