Production of electrically conducting plastic composites by three-dimensional chaotic mixing of melts and powder additives

Extended micron-scale structures were produced in thermoplastic melts from initially large clusters of conducting carbon black particles transported by three-dimensional chaotic mixing. The structures formed extensive networks that were captured by solidification and rendered the materials electrically conducting. In essence, percolating structures were constructed in situ in lieu of being the result of chance associations among particles. A systematic study was carried out to assess the influence of key parameters and to relate the electrical properties to the microstructures. Micrographs showed complex structures exhibiting patterns characteristic of chaotic advection. Electrical measurements indicated that conductivity was achieved at carbon black concentrations significantly lower than those achievable by common mixing methods and lower than those reported recently for two-dimensional chaotic mixing.