Polymeric nanocomposites (PNC) of polstyrene (PS) with organoclay were studied for their rheological and mechanical behavior. The organoclay (COPS) is a product of clay quaternization with a copolymer of styrene with vinyl benzyl tri-methyl ammonium chloride. PNC preparation and characterization was described in Part, I of this paper. The clay platelets in COPS and its PNC's are well dispersed, i.e. with the interlayer spacings of d(001) = 7-8 nm. By contrast, d(001) = 3-4 nm for PNC with Cloisite (R) 10A. However, the COPS in PS formed large, deformable domains. At concentration exceeding 5.9-wt% of COPS, the domains started to form a three-dimensional network with enhanced elasticity and progressive viscoelastic non-linearity. At temperatures of 160-180 degrees C the neat COPS did not flow; its behavior resembled that of a crosslinked elastomer. Application of the time-temperature superposition led to master Curves of bending moduli Vs. 19 decades of reduced frequency. The Curves indicated a transition at ca. 180 degrees C, most likely associated with the disintegration of ammonium ion clusters. With the same amount of clay the mechanical properties of PNC with COPS were slightly worse than those with Cloisite (R) 10A - the immiscibility of COPS, and the presence of extractable (by the matrix) low molecular weight compounds explain the behavior. (c) 2005 Elsevier Ltd. All rights reserved.