This study was devoted to the effect of extensional flow during film extrusion on the formation of the beta-crystalline phase and on the piezoelectric properties of the extruded poly(vinylidine fluoride) (PVDF) films after cold drawing. The PVDF films were extruded at different draw ratios with two different dies, a conventional slit die and a two-channel die, of which the latter was capable of applying high extensional flow to the PVDF melt. The PVDF films prepared with the two-channel die were drawn at different temperatures, strain rates, and strains. The optimum stretching conditions for the achievement of the maximum beta-phase content were determined as follows: temperature = 90 degrees C, strain = 500%, and strain rate = 0.083 s(-1). The samples prepared from the dies were then drawn under optimum stretching conditions, and their beta-phase content and piezoelectric strain coefficient (d(33)) values were compared at equal draw ratios. Measured by the Fourier transform infrared technique, a maximum of 82% beta-phase content was obtained for the samples prepared with the two-channel die, which was 7% higher than that of the samples prepared by the slit die. The d(33) value of the two-channel die was 35 pC/N, which was also 5 pC/N higher than that of the samples prepared with the slit die. (c) 2007 Wiley Periodicals, Inc.