Research On The Influence Of Polarization Condition On The Charge Storage Performance And The Piezoelectric Properties Of Perfluoropolymer THV Electret

With the development of electronic technology, microelectronic devices become smaller in their bulk and lower in their power consumption. They take a long time to work independently, and the energy they need also changes. Traditional power generation methods can’t effectively provide energy for microelectronic devices. Electret micro-generator can effectively collect structural vibration energy in the surrounding environment. The research of electret micro-generator is still in its infancy, and the output power is still unable to meet the needs of practical applications. The key problem is to getting the high-performance electret material which provides high surface charge density and long-term stability of charges. We studied the charge storage capability and piezoelectric properties of terpolymer THV composed of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, and studied the influence of three monomers on electret properties of THV based on the exiting research results. The main contents and results of this paper are as follows:(1)THV221, THV500 and THV815 film materials with different monomer content were prepared by the method of high temperature melting hot pressing.(2)The influence of thermal polarization temperature on the charge storage performance of THV was studied. The results show that the charge storage performance of THV221 is poor; the charge storage performance is good when thermal polarization temperature near the melting point and the charge storage performance of THV decreases significantly when there is a big difference between thermal polarization temperature and the melting point for THV500 and THV815.(3) The influence of electric field of polarization on the charge storage performance of THV was studied. The results show that THV of different composition exhibits different charge storage properties under different electric field of polarization. The surface potential is low under the conditions of different electric field for THV221. THV500 becomes homocharge electret under the conditions of different electric field, and achieves the best performance when the electric field intensity is between 8MV/m and 10MV/m. THV815 becomes homocharge electret and the charge storage performance is good when electric filed intensity is more than 25MV/m; it becomes heterocharge electret when electric field intensity is less than 15MV/m and achieves the best performance when electric field intensity is 11MV/m.(4)The piezoelectric properties of THV was studied after thermal polarization. The results show that the piezoelectric properties of THV221 and THV500 is good, and the piezoelectric properties of THV815 is poor. The highest piezoelectric coefficient d33 of THV221 and THV500 is 235pC/N and 330pC/N respectively. But the best piezoelectric coefficient d33 of THV815 is only 30pC/N.(5)The influence of polarization temperature on the piezoelectric properties of THV221 and THV500 shows that there is significant correlation between piezoelectric properties and polarization temperature. The higher the polarization temperature is, the higher the piezoelectric coefficient of THV221 and THV500 becomes when the polarization temperature is below the melting point, and the piezoelectric coefficient reaches the maximum at melting point.(6)The research of THV221 and THV500 under different electric field of polarization shows that the piezoelectric coefficient increases when electric filed intensity of polarization increases. The highest piezoelectric coefficient of THV221 is achieved when electric field intensity is 8.1MV/m. The highest piezoelectric coefficient of THV500 is achieved when electric field intensity is more than 10MV/m and remains substantially constant.