Title :
Dielectric and mechanical behaviour of ordered polyurethane networks based on mesogenic diol
Author :
Ilavský, M. ; Valentová, H. ; Nedbal, J. ; Sedláková, Z.
Author_Institution :
Fac. of Math. & Phys., Charles Univ., Prague, Czech Republic
Abstract :
In this work we have studied the effect of ordered structure of polyurethane LCNs, based on poly(oxypropylene)triol (T), 2(4)-methyl-1,3-phenylene diisocyanate (Dr) and the mesogenic diol (D) cured at isotropic state, on the dielectric and dynamic mechanical behaviour. As was shown previously for uncrosslinked polymer from D and DI by DSC, X-ray scattering and polarizing microscopy, a nematic phase forms on cooling and freezes into the LC glassy state. On heating, the mesophase melts and, subsequently, a better-ordered smectic phase is formed at 110 °C, melting at 130°C
Keywords :
dielectric polarisation; dielectric relaxation; liquid crystal phase transformations; liquid crystal polymers; smectic liquid crystals; 2(4)-methyl-1,3-phenylene diisocyanate; X-ray scattering; cooling; freezes; melts; mesogenic diol; ordered polyurethane networks; polarizing microscopy; poly(oxypropylene)triol; smectic phase; Chemicals; Cooling; Dielectric measurements; Electrochemical impedance spectroscopy; Frequency measurement; Polarization; Polymers; Shape measurement; Temperature dependence; X-ray scattering;
Conference_Titel :
Electrets, 1999. ISE 10. Proceedings. 10th International Symposium on
Conference_Location :
Athens
Print_ISBN :
0-7803-5025-1
DOI :
10.1109/ISE.1999.832115
