Silver fillers aspect ratio influence on electrical and thermal conductivity in PEEK/Ag nanocomposites

Abstract

The development of polymer based conductive composites is required in aeronautical applications where electrostatic charges and heat need to be evacuated. Optimization of conductive filler content is necessary to maintain low density and high mechanical properties provided by the polymer matrix. We introduced silver nanoparticles in Polyetheretherketone. Electrical conductivity, specific heat capacity, thermal conductivity and thermal diffusivity have been determined as a function of filler content and temperature. In particular, we studied the influence of silver nanoparticles aspect ratio on these thermal properties. We compared nanospheres with nanowires. A low electrical percolation threshold (0.55vol%) is obtained for silver nanowires composites compared to spherical particles (10.8vol%). Thermal conductivity increases with silver content and the influence of filler aspect ratio is interesting: thanks to nanowires, the thermal conductivity enhancement is reached for lower silver content. Experimental data are well fitted with Nan model. Specific heat capacity decreases with the introduction of silver nanoparticles, following the mixture rule independently of aspect ratio. Composites thermal diffusivity also increases with increasing silver content and influence of filler aspect ratio can be brought to light. Temperature dependence of these thermal properties indicate a dominant heat transport mechanism typical of disordered materials.