Size, Concentration and Content Effect of Copper/Graphite Hybrid Dopant on Mechanical, Thermal and Electrical Conductivity Characteristics of Unsaturated Polyester Resin

In this paper, mechanical, thermal, electrical, and physical properties of unsaturated polyester resin with dendritic-shaped copper(Cu)-graphite (Gr) fillers were experimentally investigated and correlations were proposed with several theoretical models. On the other hand, the Gr filler is added as a secondary filler to provide synergy and obtain better conductivities. For this purpose, 5 wt% Gr filler was added as a secondary filler while Cu was added with changing weight rates. In each experiment, the basic aim is to determine the effects of both filler size and concentration on the mechanical, thermal, and electrical characterizations of the composite mixture. It is observed that an increase in filler concentration causes an increase in thermal conductivities. On the contrary, the coefficient of thermal expansion and specific heat decrease with increasing filler content. The hybrid filler allows the positive synergistic effect on mechanical performance but restricts conductivity properties. The particle size also causes a minimal linear increase in thermal conductivity. Thermal analysis such as thermogravimetric analysis and differential scanning calorimetry show that the thermal stability increases with the filler concentration. On the other hand, the electrical conductivity increases with increasing filler particle size and concentration. Using this high conductive novel composite mixture as an electrode hard steel parts were engraved in an electric discharge machine. Regarding the experimental-theoretical correlation, the best agreement is achieved with the Maxwell model.