NMR-STUDY OF THE FERROELECTRIC PHASE-TRANSITION IN A 70/30 MOL-PERCENT COPOLYMER OF VINYLIDENE FLUORIDE (VF2) AND TRIFLUOROETHYLENE (TRFE)

被引:46
作者
LEGRAND, JF [1 ]
SCHUELE, PJ [1 ]
SCHMIDT, VH [1 ]
MINIER, M [1 ]
机构
[1] UNIV GRENOBLE 1,SPECTROMETRIE PHYS LAB,F-38402 ST MARTIN DHERES,FRANCE
关键词
CRYSTALS - Structure - FERROELECTRICITY - FLUORINE CONTAINING POLYMERS - SPECTROMETERS; MAGNETIC RESONANCE;
D O I
10.1016/0032-3861(85)90286-1
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
Nuclear magnetic resonance studies of **1**9F nuclei in a 70/30 mol% random copolymer of vinylidene fluoride and trifluoroethylene were performed at 9. 14 MHz and 20. 0 MHz. The free induction decays (FIDs) were analysed in terms of two components attributed to the amorphous and crystalline portions of the polymer. The changes in crystallinity as well as the effects of the ferroelectric transition were observed during cycles of heating and cooling between 20 degree C and 140 degree C. The spin-lattice relaxation was also investigated. From measurements at 9. 14 MHz the observed longitudinal relaxation time T//1 appears to be dominated by the dynamics of the amorphous phase and exhibits no anomaly through the phase transition. However, from measurements at 20 MHz, well defined minima of T//1 were observed, which are associated with the ferroelectric transition (especially after repeated annealing of the samples. Results are discussed in terms of the crystalline phase structure, which appears dynamically disordered above the ferroelectric phase transition. An analogy is considered with the plastic phase transitions encountered in molecular crystals.
引用
收藏
页码:1683 / 1688
页数:6
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