CREATION OF CONDUCTING NETWORKS AMONG PARTICLES IN POLYMER MELTS BY CHAOTIC MIXING

Chaotic mixing of a nonconducting thermoplastic melt and initially coa rse clusters of conducting particles has been investigated to assess o pportunities 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, spheric al, non-interacting particles was studied computationally and experime ntally in a cavity formed between two offset cylinders. Numerical trac king of individual particles was performed under conditions where glob al chaotic mixing prevailed. Formation mechanisms were identified at v arious stages of mixing. After mixing, networks comprising interconnec ted particles were identified as electrical pathways. Micrographs of c omposites produced experimentally by two-dimensional chaotic mixing of thermoplastics with conducting carbon black showed structures resembl ing those predicted by the simulations and provided further insights i nto formation mechanisms. The electrical resistivity of the composites is also compared to composites produced by conventional means.