孔洞结构聚丙烯铁电驻极体薄膜的压电性研究

为了提高孔洞结构聚丙烯(cellular PP)铁电驻极体的压电性能,采用高压气体膨化技术对材料进行了改性处理,并利用准静态和干涉仪测量方法,对经处理的cellular PP铁电驻极体薄膜的压电效应进行了研究.结果表明:气体膨化工艺能够明显提高cellular PP铁电驻极体薄膜的压电活性:这种突出的压电活性源干膨化膜杨氏模量Y的降低和电极化能力的提高;压电系数d33随频率的增加呈现下降趋势:从0.01 Hz下的1200 pC/N降低到共振频率附近的350 pC/N;对于不同参数处理的样品,它们的共振频率在150～400 kHz;大多数样品的d33在0.2～10 kPa的范围内没有明显的变化,但是高于10 kPa,d33随之下降;cellular PP铁电驻极体薄膜d33的热稳定性与非孔洞型PP驻极体薄膜的电荷储存热稳定性相当.

Piezoelectricity of ferroelectret polypropylene with cellular structure

The pressed-air expansion technique was used to improve the piezoelectricity of cellular polypropylene(PP) ferroelectret. The piezoelectricity of the expanded PP ferroelectret was investigated by quasistatic and interferometric methods. The results show that the piezoelectric activity of cellular PP films can be significantlyincreased by thickness-expansion. The high piezoelectric activity is due to the reduction of Young’ s modulus and the increase of chargeability of the expanded PP films. The d33-coefficient decreases with the rise of frequency; from 1200 pC/N at 0. 001 Hz to 350 pC/N just below the resonance frequency. The resonance frequency locates in the range of 150 to 400 kHz for differently treated samples. Static pressures up to 10 kPa have little influence on d33, but higher pressures result in a reversible decrease. The thermal stability of piezoelectric activity for such PP ferroelectret is similar to that of solid PP electret.