Journal of Polymer Science Part B: Polymer Physics, Vol.32, No.2, 313-323, 1994
Effects of an Electrostatic-Field on Crystallization of Poly(Vinylidene Fluoride)
Melt crystallization of poly(vinylidene fluoride) (PVF2) under a static electric field was studied by optical microscopy. For most crystallization temperatures a mixture of alpha and gamma spherulites was obtained. The growth rate of the spherulites was measured in the plane perpendicular to the direction of the field. The effect of an electric field on the growth rate of the alpha spherulites corresponds in a qualitative way with the dependence predicted theoretically for the primary nucleation of the nonpolar form. It is shown, that the growth rate of alpha spherulites is always reduced by the electric field. This reduction was larger the lower the undercooling. In the case of gamma spherulites the interpretation of the results is more complicated. Both the morphology and the growth rate of gamma spherulites under an electric field depend on electrode configuration. An increase of the growth rate of gamma spherulites in an electric field was detected only when the sample was in direct contact with both electrodes. Under these circumstances, gamma spherulites nucleate and grow at the PVF2-positive electrode interface; and the increase of the growth rate is higher the lower the undercooling, and is greater in comparison with the decrease found for the nonpolar alpha phase. The reason for the sensitivity of the morphology of the gamma form to the electrode configuration is not completely clear.