Response surface methodology was used to analyze the effect of glycerol (X-1) and ethylene-acrylic acid (EAA) level (X-2) on the objective (water solubility index (WSI), water absorption index (WAI), and tensile strength) attributes of a poly(vinyl alcohol) (PVOH)/starch-blencled plastic resin. A rotable central composite design was used to develop models for the objective responses. The experiments were run with different barrel temperatures, such as zone 1: 100 degrees C, zone 2: 100 degrees C, zone 3: 105 degrees C, and zone 4: 105 degrees C, respectively, with a feed rate of 20 g/min and screw speed of 25 rpm. Responses were most affected by changes in glycerol level (XI) and to a lesser extent by EAA level (X2). Individual contour plots of the different responses were overlaid, and regions meeting the Optimum WSI of 6.10%, WAI of 5.57 g gel/g dry wt, and tensile strength of 62.14 MPa were identified at the glycerol level of 72.41 mL and the EAA level of 36.03 g, respectively. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 2915-2921, 2009