High performance particle-reinforced epoxy composites with industrial grade graphite, GNPs and hBN: a comparative study

The lightweighting of electronic components such as heat is highly demanded by the market. The use of polymers to replace metal parts can be a viable solution. However, the weak mechanical and thermal performance of polymers represent a criticality. This work studies the introduction of three different industrial-grade fillers (graphite, graphene nanoplatelets, and hexagonal boron nitrate) in three different concentrations (2.5, 5, and 10 wt%) into an epoxy matrix by evaluating thermal and electrical performances. In addition, a study was carried out on the tribological properties and stiffness of the composites through wear and FIMEC tests for the first time in literature. The thermal performance improved with increasing filler concentration, with GNPs-10 wt% showing the highest enhancement with a 105.52% improvement in thermal performance. The same scenario turns out to be the best in tribological terms with a 98.86% improvement in wear resistance and a friction against steel of about 0.35, thanks to the formation of a graphene tribo-film. GNPs and graphene composites also exhibited a remarkable electrical conductivity, with 10 wt% scenarios being the best performers (78.4 kΩ·mm resistivity). In addition, FIMEC tests revealed that the particle reinforcement initially increased stiffness (with a 65% improvement for Graphite 5 wt%), but higher concentrations could lead to local embrittlement decreasing the mechanical properties.