(133d) Microstructural Variations of Various Commercial Single-Walled Carbon Nanotubes Dispersed in Unsaturated Polyester Resin

In this work, the dispersion states of different single-walled carbon nanotube (SWNT) grades in unsaturated polyester resin (UPR) were investigated using rheology and microscopy. SG65 and CG200 SWNT from Southwest Nanotechnologies were dispersed in UPR by a previously reported high shear mixing method. The SG65 grade has a dominant (6, 5) chiral content and lower pure SWNT composition; the CG200 grade is dominant in metallic chirality with higher pure SWNT content. Atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS) showed similar SWNT aspect ratios and surface chemistries. Oscillatory and steady shear rheology of the dispersions at similar volume fractions of pure SWNT showed noticeable variations in storage and viscous moduli, crossover frequencies and low shear viscosities. These differences indicate differences in the dispersion microstructure. Since properties of polymer nanocomposites depend on the SWNT dispersion state, the observed rheological variations are expected to correlate to differences in cured composite properties. This work demonstrates that actual SWNT content and chirality can significantly contribute to dispersion microstructure.  Thus, the availability of more commercial SWNT grades has made SWNT type selection an important criterion for achieving nanocomposites with enhanced properties.