- 學位論文
孔洞壓電駐極體薄膜製程開發與特性分析
Development and Analysis of a Cellular Piezo-Electret Film
摘要
本論文以孔洞壓電駐極體薄膜製程開發與特性分析為研究主軸，將壓電高分子聚合物P(VDF-TrFE)與PVDF-HFP作為薄膜材料，開發塗佈與浸泡乙醇的濕式相轉變法，使薄膜中產生孔洞結構，並利用電暈放電極化使其具有壓電、焦電及鐵電效應，以實現孔洞壓電駐極體的製程開發。本研究中使用市售之d33 meter與靜電測定器長時間量測薄膜的壓電係數與表面電位變化，發現P89%的孔洞薄膜具有最佳的穩定性，再利用自行架設的動態法透過施加在試片上的應力與試片所產生的電荷計算出P89%孔洞薄膜的壓電係數為44.374 pC/N，為實心聚偏氟乙烯壓電薄膜的2.21倍。另外，利用雷射強度調變法將不同頻率的熱脈衝施加於駐極體薄膜表面，使其產生焦電效應之電流，而最大電流值為3.56 pA，再透過鎖相放大器區分出電流的實部與虛部，代入Fredholm integral equation of the first kind的電流基本方程式中，利用高斯求積法計算出空間電荷與偶極極化量在駐極體薄膜中的分布與貢獻，結果顯示空間電荷與偶極極化量皆主要分布於薄膜的上下表面，呈現接近對稱的U字型分布。此孔洞壓電駐極體將可利用外加電場驅動材料中的偶極極化量，量測空間電荷所產生的訊號，以達成自感應致動器的製作。
並列摘要
This thesis focuses on the development and analysis of cellular piezo-electret film fabricated from poly(vinylidene fluoride)-co-trifluoroethylene (P(VDF-TrFE)) and poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP) polymers. The cellular film is made by the wet phase inversion method and ethanol soaking. Corona discharge is used to conduct poling and charge injections for storing charges in film cavities and creating piezoelectric and pyroelectric effect. Experimental results verified that using the developed fabrication method, the cellular structure can successfully create in the electret film. In this study, a commercial d33 meter and an electrostatic voltmeter were used to measure the piezoelectric coefficient and long-term variation of the surface potential change. It is found that the P89% porous film has the highest stability. Then, dynamic method is applied to measure the piezoelectric constant, the average d33 value of the P89% porous electret is 44.374 pC/N, which is 2.21 times of the solid polyvinylidene difluoride (PVDF) film. In addition, the laser-intensity modulation method is to apply to study its pyroelectric effect current under different pulse frequencies, the maximum current value is 3.56 pA. The real part and the imaginary part of measured current is distinguished through the lock-in amplifier, and substituting into the fundamental current equation, and using Fredholm integral equation of the first kind to study the contributions of dipoles and space charges. Using Gaussian quadrature, the distribution and contribution of space charge and polarization in the electret film are calculated. The results show that the space charge and the polarization are mainly distributed on the upper and lower surfaces of the film, and it is a nearly symmetrical U-shaped distribution. The cellular piezo-electret will be able to use an external electric field to drive the polarization in the material, measure the signal of space charge, and achieve the production of self-sensing actuator.