  The viscosity of Graphene nano-sheet suspensions (GNS)and its behavior with
temperature and concentration have been experimentally determined. A physical
mechanism for the enhanced viscosity over the base fluids has been proposed for
the poly-dispersed GNSs. Experimental data reveals that enhancement of
viscosity for GNSs lie in between that of Carbon Nanotube Suspensions (CNTSs)
and nano Alumina suspensions (nAS) , indicating the hybrid mechanism of
percolation (like CNTs) and Brownian motion assisted sheet dynamics (like
Alumina particles). Sheet dynamics and percolation, along with a proposed
percolation Network Dynamicity Factor; have been used to determine a
dimensionally consistent analytical model to accurately determine and explain
the viscosity of poly-dispersed GNSs. It has been hypothesized that the dynamic
sheets behave qualitatively analogous to gas molecules. The model also provides
insight into the mechanisms of viscous behavior of different dilute
nanoparticle suspensions. The model has been found to be in agreement with the
GNS experimental data, and even for CNT and nano Alumina suspensions.
