Abstract
The effect of electric field strength upon the rate of overall crystallization, crystal morphology, and crystal modifications was investigated by studying the melt-crystallization of poly(vinylidene fluoride) in the presence of an external dc electric field of 0~0.09 MV/cm. With increase in the exectric field strength. the temperature at which tar electro-active polar ${\gamma}$-crystal begins to form decreased and the ${\gamma}$-crystal content increased with reduction in the content of the electro-inactive $\alpha$-crystal. The transition of $\alpha$-crystal to ${\gamma}$-crystal was found to be suppressed by the electric field in the course of the isothermal melt-crystallization. The electric field did not have a significant effect on the rate of overall crystallization at 150~ 154 $^{\circ}C$ where only $\alpha$-crystal was formed. However, the rate of crystallization was reduced by the electric field at slightly higher temperatures (ca. 156-158$^{\circ}C$) where a mixture of $\alpha$- and ${\gamma}$-crystals was formed, whereas the electric field increased the rate of crystallization at 160-162 $^{\circ}C$ where ${\gamma}$-crystal was preferentially formed.
