Montmorillonite-filled nanocomposites were prepared by the thermal copolymerization of tung oil (TUNG), styrene (ST), and divinylbenzene (DVB). These nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical analysis (DMA), and their mechanical properties. The XRD of the modified montmorillonite exhibited a peak that vanished completely in the nanocomposites. Thus, the XRD results apparently indicate a distortion of the platy layers of the nanofiller in the TUNG-ST-DVB polymers. A platy nanolayered structure of the modified montmorillonite in the TUNG-ST-DVB polymers was observed by TEM. The extent of separation of the platy layers as observed by the TEM reached a maximum for the 5% modified nanofiller (at a fixed polymer composition), 50%-oil-containing polymer (at a fixed nanofiller concentration of 5%), and TUNG intragallery nanocomposites (at both fixed polymer and nanofiller concentrations). The DMA results show a broadened glass-transition temperature along with a hump for these nanofilled polymers, indicating the presence as a majority constituent of a copolymer consisting of TUNG and aromatics, along with a grafted TUNG polymer, respectively. The improvements in the Young's modulus and compressive strength upon incorporation of the nanofiller indicated the presence of a partially intercalated and distorted platy-layered structure of the nanofiller. However, from the results of all of these studies, it was tough to estimate the exact level of delamination/exfoliation in these TUNG nanocomoposites. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1297-1306, 2011