Structural and electrical properties of MgCl2-filled PVDF films

Polyvinylidene fluoride (PVDF) films, filled with various mass fractions (w less than or equal to 15%) of MgCl2, were prepared. The effect of crystalline and electronic structural variations, due to filling level, on the d.c.-electric conduction was investigated. PVDF (alpha- and beta-) partially crystalline phases were detected by Xray analysis. The degree of crystallinity increased by filling and a maximum P-phase content was found at w = 0.5%. The infrared analysis confirmed the presence of: a- and P-phases, a head-to-head content of similar to 12%, and polaron defects. UV-visible optical absorption analysis revealed a change in the optical gap value at w = 0.1%. A one-dimensional phonon-assisted charge carrier hopping (interpolaron) conduction mechanism was used to interpret the d.c. electrical resistivity results. The calculated hopping site concentration implied that only 0.4 or 0.2 of the head-to-head defects contribute to the conduction process. (C) 1999 Elsevier Science Ltd. All rights reserved.