Title :
The Investigation of α⇒β phase transition in poly(vinylidene fluoride) (PVDF)
Author :
Constantino, C.J.L. ; Job, A.E. ; Simões, R.D. ; Giacometti, J.A. ; Zucolotto, V. ; Oliveira, O.N., Jr. ; Gozzi, G. ; Chinaglia, D.L.
Author_Institution :
Fac. de Ciencias e Technol., UNESP, Presidente Prudente, Brazil
Abstract :
The phase transition from the non-polar α-phase to the polar β-phase of poly(vinylidene fluoride) (PVDF) has been investigated using micro-Raman spectroscopy, which is advantageous for being a non-destructive technique. Films of a-PVDF were subjected to stretching under controlled rates and at 80 °C, the transition to β-PVDF being monitored by the decrease in the Raman band at 794 cm-1 characteristic of the α-phase, with the concomitant increase in the 839 cm-1 band characteristic of the β-phase. Poling with negative corona discharge was found to affect the a-PVDF morphology improving the Raman bands related to this crystalline phase. This effect is minimized for films stretched to higher ratios. Significantly, corona-induced effects could not be observed with the other experimental techniques, viz, X-ray diffraction and infrared spectroscopy.
Keywords :
Raman spectra; corona; deformation; dielectric polarisation; nondestructive testing; phase transformations; polymer films; 794 cm-1; 80 C; 839 cm-1; Raman band; X-ray diffraction; a-PVDF morphology; crystalline phase; infrared spectroscopy; micro-Raman spectroscopy; negative corona discharge; nondestructive technique; nonpolar phase; phase transition; polar phase; poling; poly(vinylidene fluoride) film; stretching; Corona; Crystallization; Ferroelectric films; Infrared spectra; Lattices; Monitoring; Morphology; Raman scattering; Spectroscopy; X-ray diffraction;
Conference_Titel :
Electrets, 2005. ISE-12. 2005 12th International Symposium on
Print_ISBN :
0-7803-9116-0
DOI :
10.1109/ISE.2005.1612350
