Abstract: With the growing demand for faster and more powerful computing, effective heat dissipation is essential to ensure the longevity, reliability, and high performance of electronic systems. In the field of modern electronic packaging materials, there is a great need for graphitic material-loaded polymeric composites (GPCs) with excellent thermal conductivities. However, the enhancement efficiency of GPCs is hindered by the agglomeration of fillers and the interfacial thermal resistance caused by the lack of continuous thermally conductive pathways between the filler and matrix. Understanding the interfaces between filler and matrix is of great importance in optimizing the performances of GPCs. Here, we fabricated graphite nanofibers (GNF)-loaded nanocomposites using acid-functionalized GNF (AGNF) and acid-tetraethylenepentamine-functionalized (TGNF) as a filler and epoxy resin as a matrix with different GNF loading contents to explore the interfacial properties of the nanocomposites. The optimal GNF loading for AGNF was 0.5 wt.%, while the TGNF showed 0.75 wt.%. The highest thermal conductivity (0.51 W m^-1 K^-1) and fracture toughness (25.8 MPa m^1/2) values were found in the TGNF-loaded nanocomposites with a fraction of 0.75 wt.%, representing enhancements of ∼145% and ∼400%, respectively, compared to those of neat nanocomposites. The experimental data presented herein demonstrate that the interfacial properties play a significant role in enhancing the thermal and mechanical performances of the nanocomposites. The present approach is expected to serve as a valuable tool in the design of conductive polymeric nanocomposites for further practical applications, such as thermal interface materials and packaging of high-power electric devices.

Key words: Graphite nanofiber, Nanocomposites, Interfacial interaction, Thermal conductivity, Fracture resistance