【摘要】 利用准静态法和激光干涉法测量正、逆压电d33系数,研究了经压力膨化处理的聚丙烯孔洞型铁电驻极体薄膜压电系数的压强和频率特性及其热稳定性。结果表明,聚丙烯薄膜经压力膨化处理后,其压电性能改善的原因是:压力膨化处理既能有效地降低孔洞膜的弹性模量Y,又能增强其储电能力。聚丙烯孔洞膜的压电d33系数在激励信号压强为0.2~4kPa的范围内基本保持恒定,但当其值高于4kPa时,d33系数出现了明显的下降。聚丙烯孔洞膜的压电d33系数随频率上升而下降(即从0.001Hz时的1200pC/N降低到其机械共振频率附近时的350pC/N),是与材料的弹性模量Y随频率的上升而增加直接相关。对不同工艺参数制备的样品,其机械共振频率位于150~400kHz范围内。实验结果还表明:聚丙烯孔洞膜的压电d33系数的热稳定性与非孔洞型聚丙烯驻极体薄膜的电荷储存热稳定性相近。更多还原

【Abstract】 The piezoelectric activity of charged cellular polypropylene（PP） films,treated by thickness-expansion,was investigated by measuring the quasistatic and dynamic d₃₃-coefficients.It is found that d₃₃-coefficients can be improved significantly by thickness-expansion.This is due to the enhanced charging capability and the decrease of elastic modulus Y of such materials.The d₃₃-coefficients are independent on the applied pressure in the range of 0.2～4kPa.The d₃₃-coefficient,measured by quasistatic and interferometric methods,is found to be as high as 1200pC/N at 0.001Hz,decreasing to 350pC/N just below resonance.The thermal stability of such cellular PP ferroelectret film is similar to that of solid PP film electret.更多还原