多孔聚丙烯薄膜駐極體之製程開發與特性分析

Analysis and development of electret in cellular Polypropylene films

簡嘉政(Chia-Cheng Chien)

指導教授 ： 李世光 ； 吳光鐘

共同指導教授 ： 許聿翔(Yu-Hsiang Hsu)

國立臺灣大學/工學院/應用力學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202003390

摘要

本論文以多孔聚丙烯駐極體的製程開發與特性分析為研究主軸，聚丙烯駐極體的可撓性使其在軟性電子元件上備受重視。本研究以商業用的聚丙烯合成膜為材料，透過設計高壓腔體與氣體擴散膨脹法，加熱聚丙烯薄膜，使其內部孔洞產生膨脹，並利用電暈極化，使其擁有駐電、熱電及壓電效應，以實現多孔駐極體之製程開發。本研究並利用雷射強度調變法產生不同頻率下的熱脈衝施加在聚丙烯駐極體表面上，使駐極體產生熱電效應之電流並加以觀察，其電流峰對峰值最高可達5.5pA。再透過鎖相放大器比較出電流的實部及虛部。本研究亦將所得之電流的實部及虛部分布曲線代入Fredholm integral equation of the first kind的駐極體電流基本方程式，討論在各情況下計算複數電流與假設傅立葉級數對空間電荷與極化量分布之影響，以探討駐極體之應用範圍。此外本研究還開發測量壓電係數d33之動態法，利用震盪器所產生之加速度對駐極體施以應力，量測其產生之電荷密度並透過壓電本構方程式計算出d33為124.98pC/N，為一般聚偏二氟乙烯壓電薄膜之6.21倍大，再透過準靜態法藉此了解自製之多孔駐極體PQ60在準靜態或低頻率上的優勢，可以達到266.14 pC/N。這些特性都一再顯現了駐極體在可撓性感測器與致動器上的發展空間。

關鍵字

多孔駐極體 ； 壓電效應 ； 熱電效應 ； 動態法 ； 雷射強度調變法

並列摘要

This thesis focuses on the development and analysis of cellular electret fabricated from commercial polypropylene (PP) films. The flexibility of PP electret makes it an excellent candidate for soft electronic component. The commercial PP films (PQ60) is transferred into cellular electrets by using Gas diffusion expansion (GDE). PP films are inflated to form layered porous structure. Corona discharge is then used to inject electrons and makes pores to store charges creating pyroelectric and piezoelectric effect. Experimental results verified that using these processes, we have successfully converted PP films into the cellular electret films. Moreover, Laser-Intensity-Modulation method is applied to analyze the pyroelectric effect. Modulating laser intensity in different frequencies, the highest peak-to-peak current can reach up to 5.5 pA. Then the lock-in amplifier is used measure complex current. Substituting the complex current into electret fundamental equation, Fredholm integral equation of the first kind, and using Fourier series, the distribution of space charge and polarization in electret are analyzed and discussed. Finally, Dynamic method is applied to measure the piezoelectric constant d33 of the cellular electret. The average piezoelectric constant of PP cellular electret is 124.98 pC/N, and it is 6.21 times than the general polyvinylidene difluoride (PVDF) films. And use quasi-static measurement to measure piezoelectric constant which is 266.14 pC/N. These experimental results suggest that the developed cellular electret has a potential to be applied in the field of flexible sensor and actuator.

並列關鍵字

cellular electret ； piezoelectric effect ； pyroelectric effect ； Dynamic method ； Laser-Intensity-modulation method

參考文獻

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