The addition of nano-sized particles into a polymer matrix is an excellent way to manipulate polymer properties. Our current efforts try to understand how a material's properties are influenced by parameters such as temperature, particle size, and particle concentrations of additives. This paper presents the rheological behavior of polycarbonate (PC) and low density polyethylene (LDPE) containing at least 2.5% and 5% weight fractions of functionalized and un-functionalized carbon nanotubes (CNTs). These materials were investigated using steady shear and oscillatory rheometry over a range of processing temperatures. The properties examined through rheological experimentation include: viscosity, critical strain, storage modulus (G'), and loss modulus (G ). The nanocomposites samples were examined using scanning electron microscopy (SEM) and UV light microscopy.