权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Development of Thermo-Stable Piezoelectric Polymers and Their Applications to Ultrasonic Transducers

热稳定压电聚合物的开发及其在超声波换能器中的应用

基本信息

批准号：
04555212
负责人：
OHIGASHI Hiroji
金额：
$ 7.23万
依托单位：
Yamagata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

This research project was performed for development of new piezoelectricpolymer materials having the electromechanical coupling factor kt more than 0.25 and durable for use under high-temperature ambient condition. Crystallization of poly ( vinylidene-fluoride ) in the hexagonal phase, which appears only at highpressure and temperatures, yielded a film comprizing extended chain lamellar crystals of the beta-form crystal structure. The resulting film has a kt value of 0.27, and retains its piezoelectric activityup to the temperatures just below the melting point, 205ﾟC.High-pressure crystallized PVDF film thus much improved piezoelectric properties as compared to convential PVDF,which has a kt value of 0.2, and loses its activity at 120ﾟC.The usefulness of the newly developed PVDF film as an ultrasonic transducer material working at the megahertz frequency range was demonstrated by constructing ultrasonic transducers which operated effectively at 180-200ﾟC.In addition to the above mentioned results, we have many additional results important both technologically and scientifically. Some of them are as follows :( 1 ) Pressure dependence of Curie temperature and melting point for PVDFand P ( VDF-TrFE ) ( VDF Trifluoroethylenecopolymers ) was determined.( 2 ) Ferroelectic domain structure in a single crystal lamellae of P ( VDF-TrFE ) was first observed by TEM.( 3 ) Anisotropic motion of chainmolecules in a single crystalline lamella of P ( VDF-TrFE ) was detected by usingAT-cut quartz resonators ; the moleculesin the paraelectric phase are very mobilealong the direction parallel to the chain axis like liquid, while they are ridgid for the shear stress across the chainaxis.( 4 ) Highly-doublly-oriented films ( single crystal like films ) of P (VDF-TrFE ) were found to be fabricated by a special treatment techmique.

本研究旨在开发机电耦合系数kt大于0.25、耐高温的新型压电聚合物材料。聚偏二氟乙烯在六方相中的结晶仅在高压和高温下出现，产生了具有β型晶体结构的延伸链层状晶体的膜。所得膜的kt值为0.27，并且在刚好低于熔点205 ℃的温度下保持其压电活性。与kt值为0.2的常规PVDF相比，高压结晶PVDF膜因此大大改善了压电性能，并在120 ℃时失去活性。证明了新开发的PVDF膜作为在兆赫频率范围内工作的超声换能器材料的有用性通过构造在180-200 ℃下有效工作的超声换能器，除了上述结果外，我们还有许多在技术和科学上都很重要的额外结果。（1）测定了PVDF和P（VDF-TrFE）（VDF-Trifluoroethyleneecopolymers）的居里温度和熔点随压力的变化关系。（2）首次用透射电镜观察到了P（VDF-TrFE）单晶片中的铁电畴结构。（3）用AT切石英谐振器研究了P（VDF-TrFE）单晶片层中链状分子的各向异性运动，顺电相分子沿平行于链轴的方向象液体一样运动，而沿链轴方向的剪切应力则是刚性的。（4）采用特殊的处理工艺制备了高度双取向的P（VDF-TrFE）薄膜（类单晶薄膜）。