Title :
Poling of thin films of aromatic polyurea during polymerization and crystallization
Author :
Ukishima, S. ; Onoe, K. ; Iijima, M. ; Takahashi, Y. ; Fukada, E.
Author_Institution :
Inst. for Super Mater., ULVAC Japan, Tsukuba, Japan
Abstract :
Piezoelectricity and pyroelectricity were observed in poled films of aromatic polyurea less than 1 μm thick, which were synthesized by concurrent deposition of a diamine monomer and a diisocyanate monomer in vacuum. The films are poled by applying an electric field of 100 MV/m at 200°C. X-ray diffraction measurements show that crystallization takes place at about 160°C. The infrared absorption due to C=O stretch vibration in the isocyanate groups at the chain ends disappears after heat treatment. It is concluded that the alignment of urea dipoles takes place during polymerization and crystallization. Stable residual polarization produces the piezoelectric and pyroelectric activities persistent up to 200°C
Keywords :
X-ray diffraction examination of materials; crystallisation; dielectric polarisation; dielectric thin films; electrets; infrared spectra of organic molecules and substances; piezoelectricity; polymer films; polymerisation; pyroelectricity; vacuum deposited coatings; C=O stretch vibration; X-ray diffraction; aromatic polyurea; chain ends; concurrent deposition; crystallization; electret; heat treatment; infrared absorption; isocyanate groups; piezoelectricity; poled films; poling; polymerization; pyroelectricity; residual polarization; thin films; Crystallization; Electromagnetic wave absorption; Heat treatment; Infrared heating; Piezoelectric films; Piezoelectric polarization; Piezoelectricity; Polymer films; Pyroelectricity; X-ray diffraction;
Conference_Titel :
Electrets, 1991. (ISE 7) Proceedings., 7th International Symposium on (Cat. No.91CH3029-6)
Conference_Location :
Berlin
Print_ISBN :
0-7803-0112-9
DOI :
10.1109/ISE.1991.167222
