Creation of Conducting Networks among Particles in Polymer Melts by Chaotic Mixing

Chaotic mixing of a nonconducting thermoplastic melt and initially coarse clusters of conducting particles has been investigated to assess opportunities for the in-situ formation of extended particle networks. Upon capture by solidification, such extended networks may render the composite electrically conducting. Chaotic advection of small, spherical, non-interacting particles was studied computationally and experimentally in a cavity formed between two offset cylinders. Numerical tracking of individual particles was performed under conditions where global chaotic mixing prevailed. Formation mechanisms were identified at various stages of mixing. After mixing, networks comprising interconnected particles were identified as electrical pathways. Micrographs of composites produced experimentally by two-dimensional chaotic mixing of thermoplastics with conducting carbon black showed structures resembling those predicted by the simulations and provided further insights into formation mechanisms. The electrical resistivity of the composites is also compared to composites produced by conventional means.