The effects of postextrusion conditions (i.e., the draw ratio) were studied to control the cellular structure of extruded foams based on polymer blends. High-density polyethylene and polypropylene were foamed with azodicarbonamide as a chemical blowing agent, zinc oxide as an accelerator, and Kraton D1102 as a compatibilizer. The deforrnation of the cellular structure and dispersed phase particles was measured with micrographs in both longitudinal and transversal directions to obtain a full three-dimensional picture of the foam morphology. A simple model of the cellular structure is presented to predict cell deformation. (C) 2007 Wiley Periodicals, Iic.