Dynamics of poling PVDF between 250 degrees C and 120 degrees C

摘要

PVDF films with high beta -content are poled in an electric field of 60 MV/m at temperatures between 25 degrees C and 120 degrees C. At 25 degrees C the alignment of dipoles takes place in a central poling zone during several hours of poling. When the temperature is increased to 120 degrees C the poling time necessary to align the dipoles in this narrow zone is reduced to several seconds. In addition, at temperatures higher than 90 degrees C and increased poling times the central poling zone first increases but later decreases in its dielectric displacement. Simultaneously in a 10 mu m regime adjoining the positive electrode a secondary displacement zone starts to grow. The strong reduction of this peak under short circuit conditions indicates hetero-charge accumulation in front of an anode.