Preparation and characterization of synergistically improved thermally conductive polyamide 6 with low melting point metal and low‐temperature expandable graphite

The effects of introduction of low‐temperature expandable graphite (EG) and low melting point metal‐tin (Sn) on the thermal conductivity (TC) of polyamide 6 (PA6) were investigated. After introducing 10 wt% of Sn as single filler, the TC of PA6 was nearly constant, while this value was dramatically increased to 5.187 W (mk)⁻¹ when 10 wt% of Sn was added into PA6/EG(40 wt%). The value was 90.1% higher than that of PA6/EG (40 wt%) composite, and 21.9% higher than that of PA6/EG (50 wt%), which suggested that the incorporation of EG and Sn had significant synergistic effect on the TC improvement of PA6. The electrical conductivity of the composite increased nearly 7 orders of magnitudes at the maximum filler content. Characterization of microstructure and energy spectrum analysis indicated that the dispersion of Sn in PA6/EG/Sn ternary composites was much more uniform than that of PA6/Sn binary composites. Differential scanning calorimetry measurement revealed that the crystalline peaks of Sn in PA6/EG/Sn composites disappeared and new exothermic peaks emerged at higher temperatures, which was mainly ascribed to the interaction between EG sheets and Sn. POLYM. COMPOS., 39:1818–1826, 2018. © 2016 Society of Plastics Engineers