Helical-ribbon carbon nanofiber-based nylon-6,6 nanocomposites were obtained by three processing methods: in situ polymerization, solvent processing through coagulation, and melt compounding. Composites were produced with pristine carbon nanofibers and four functionalization treatments, HNO3, O3, air/NH3, and ethylenediamine, which form sets of two liquid/gas phase treatments and two acidic/basic treatments. Dispersion was monitored at the microscale by optical microscopy, showing clear differences depending on processing and functionalization methods. The best dispersion was obtained by solvent processing, whereas the most appropriate functionalizations were obtained by air/NH3 and ethylenediamine treatments. It was observed that lower aspect ratio CNFs and stronger CNF-matrix interaction increased crystallization temperature. Percolation was not detected in the melt-compounded composites while network formation was observed at concentrations of 2 wt % in the solvent and in situ processing methods, where a high-aspect ratio was critical for performance. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012