A novel modified expanded graphite/epoxy 3D composite with ultrahigh thermal conductivity

Polymer-based composites with efficient thermal energy dissipation performance can be prospectively applied in electronics and military industry. However, significantly improving the thermal conductivity (TC) of polymer based composites is still challenging. Herein, 3D sulfanilamide-modified expanded graphite/epoxy (EG-SA/EP) composites with interconnected filler network were successfully prepared by a pre-filling and hot-pressing method. Benefiting from the interconnected network, the composite with 70 wt% EG-SA demonstrated ultrahigh bulk TC of 98 W/m & BULL;K (which exceeds some commercially-used metals) and up to 44,445% TC enhancement efficiency. Meanwhile, the EG-SA/EP composites exhibited excellent electromagnetic interference shielding performance of 85 dB (which is sufficient to block 99.9999997% of incident radiation), high electric conductivity of 7153 S/m and excellent thermal infrared response capability (the time to raise surface temperature from 19 to 82?degrees C is only 3 s). As for the mechanism of heat transfer, the 3D structure of EG-SA maintained through epoxy pre-filling in EG-SA is the main reason for the significantly improved TC. This is because the new method enables EG-SA to build a unique dense interconnected network in composites in the subsequent hot-pressing process, but the traditional direct mixing method easily destroys the inherent micro-3D structure of EG. The above excellent performances endow the EG-SA/EP composites with huge potential application value.