This study systematically investigated the drawing and ultimate tenacity properties of the Nylon 6 (NY6)/nylon 6 clay (NYC) composite fiber specimens prepared at varying NYC contents and drawing temperatures. The achievable draw ratio (Dra) values of NY6x(NYC)y as-spun fiber specimens initially increase in conjunction with NYC content, and then approach a maximum value, as their NYC contents and drawing temperature approach the 0.5 wt% and 120 degrees C, respectively. The percentage crystallinity (Xc) values of NY6x(NYC)y as-spun fiber specimens increased significantly, as their NYC contents increased from 0 to 2 wt%. As revealed by high power wide angle X-ray diffraction analysis, a form NY6 crystals grew at the expense of ? form NY6 crystals originally present in NY6x(NYC)y as-spun fiber specimens as their draw ratios increased. The ultimate modulus, tenacity, and orientation factor values of NY6x(NYC)y fiber specimens approach a maximum value, as their NYC contents and drawing temperatures approach the 0.5 wt% and 120 degrees C optimum values, respectively. The thermal and melt shear viscosity experiments were performed on NY6x(NYC)y resins and/or fiber specimens to determine the optimum NYC content and possible deformation mechanisms accounting for the interesting drawing, orientation, and ultimate tenacity properties found above. POLYM. ENG. SCI., 2012. (C) 2012 Society of Plastics Engineers