Use of exfoliated graphite filler to enhance polymer physical properties

Three sets of exfoliated graphite filled polymers, having three different particle sizes, were prepared with load levels from 0.1–20% by weight. After sieving, the particles were reduced to nanometer size through exfoliation, shear mixing, and ultrasonication, which further breaks and delaminates them. The electrical, thermal and mechanical properties of the nanoparticle filled polymers were measured. In addition, light, scanning electron, and atomic force microscope characterization were performed. The exfoliated graphite filled polymer material could be tailored to be high modulus and vary from insulating to highly conducting. Compared with the pure polymer, the polymers filled with 20% wt. exfoliated graphite has seen an significant reduction in electrical resistivity from 1.58 to 0.5 Ω cm. The thermal conductivity for the polymers containing 20% wt exfoliated graphite has also been drastically improved, increasing from 0.2 to 5 W/m K. The flexural modulus achieved a maximum increase of 3.8 GPa which is a 60% above the value for the pure polymer (2.4 GPa).