本文選題：聚偏氟乙烯 + 納米復合材料��； 參考：《北京化工大學》2017年博士論文

【摘要】：近年來,為應(yīng)對能源短缺和能源利用率較低等問題,世界上許多國家的研究人員都致力于開發(fā)新型的儲能和能量轉(zhuǎn)換裝置。由此,介電電容器由于其高功率密度、抗循環(huán)老化、性能穩(wěn)定等優(yōu)點成為研究熱點。目前,傳統(tǒng)陶瓷材料具有很高的介電常數(shù),但是其制備工藝復雜、體積大且不耐高壓。而聚合物介電材料機械性能好、易于加工且擊穿場強高,但是通常介電常數(shù)較低。因此,研究和制備具備高介電常數(shù)和擊穿場強、低介電損耗的聚合物基介電復合材料具有非常重要的意義。本論文以聚偏氟乙烯(PVDF)基聚合物為基體,研究了不同填料的尺寸與形貌、有機-無機界面及有機填料對復合膜介電行為的影響,并分析了相應(yīng)機理,建立結(jié)構(gòu)-性能的構(gòu)效關(guān)系,設(shè)計并制備了高儲能低損耗的介電復合材料。本論文的主要研究內(nèi)容如下:1.利用水熱法制備了 SnO2顆粒,粒徑5-7 nm�；跐B流理論,構(gòu)建了 SnO2/PVDF納米復合膜,在103Hz下介電常數(shù)高達320,與PVDF基體相比提高了近40倍,而介電損耗小于0.8;根據(jù)線性擬合的結(jié)果,介電行為符合滲流模型;SnO2納米顆粒具有較寬的禁帶寬度,同時,納米級的SnO2與PVDF形成的界面形成更多的電子散射和勢阱,阻止了載流子的傳輸,能夠有效地保持一定的擊穿場強。2.水熱法制備了鈦酸鈉納米管,管徑8-10 nm,管長300-500 nm,并與聚偏氟乙烯-三氟乙烯-三氟氯乙烯(PVDF-TrFE-CTFE)復合成膜。采用雙向和單向電滯回線測試探索復合膜的介電損耗機制,提出外部和內(nèi)部電導損耗共同構(gòu)成了介電材料的介電損耗。當測試頻率為10 Hz時,雙向電滯回線有上移現(xiàn)象,證明存在與填料之間和填料與聚合物基體之間的外部電導損耗的存在。利用單向電滯回線對復合膜進行測試,在100 Hz以上,其外部電導損耗不明顯,但仍然存在非線性的介電損耗,證明了存在于填料內(nèi)部的內(nèi)部電導損耗的存在。3.利用Stober法制備了不同殼厚的Ag@SiO2核殼結(jié)構(gòu)填料,Ag核大小40-55 nm,SiO2殼層厚度分別為5 nm,10 nm和20nm。由于填料的核殼型結(jié)構(gòu)使得復合膜界面極化的增強,從而提高了介電常數(shù),最高達到31;同時復合膜保持了較低的介電損耗,小于0.05。介電常數(shù)隨SiO2殼厚的增加而下降,而擊穿場強增高;在加入少量Ag@SiO2時,擊穿場強得到了提高,最高達到346 MV/m。測試結(jié)果證明SiO2殼層作為良好的絕緣層能夠降低漏電流,提高薄膜的擊穿場強。同時,薄膜的介電行為能夠通過Si02殼層厚度進行調(diào)控。4.用化學剝離法制備了層數(shù)較少的氮化硼納米片(BNNS)填料,并與PVDF-TrFE-CTFE復合,研究了 BNNS的最佳填充量;當BNNS填量為12wt%時,介電性能最好,能量釋放密度為7.1J/cm3;由于BNNS的寬禁帶寬度和高擊穿場強,介電薄膜的的擊穿場強得到提高,達到610 MV/m,BNNS的加入降低了復合材料的晶粒尺寸,從而提高了放電效率(84%)。在此基礎(chǔ)上,對納米鈦酸鋇(BT)用多巴胺進行表面修飾,制備了以BNNS和BT為填料的三相介電復合材料。利用BNNS的高擊穿場強和鈦酸鋇的高介電常數(shù),三相復合膜的介電性能得到顯著提升,介電常數(shù)最高達到76。當鈦酸鋇摻雜量為20 wt %、BNNS摻雜量為12 wt %時,三相介電薄膜的能量釋放密度最高達到13.3 J/cm3,同時放電效率為72 %。5.利用逐步加成聚合法制備了芳香聚硫脲(ArPTU)介電薄膜,由于ArPTU的非晶相極性聚合物結(jié)構(gòu),分子鏈中的偶極子能夠及時響應(yīng)電場變化,使得ArPTU具備很低的介電損耗(0.0067),同時具備很高的擊穿場強(746 MV/m)和能量釋放效率(大于90 %); ArPTU的加入改變了復合介電薄膜晶體結(jié)構(gòu)和電阻率,使得復合膜的晶粒尺寸變小,晶面間距變大,有利于PVDF-TrFE-CTFE分子鏈中偶極子的自由轉(zhuǎn)動,降低了電滯損耗,從而提高了擊穿場強和能量釋放密度。復合膜能量釋放密度在700 MV/m電場下達到19.2 J/cm3,同時,放電效率仍大于85 %。
[Abstract]:In recent years, in order to cope with the shortage of energy and the low utilization rate of energy, researchers in many countries of the world are committed to developing new energy storage and energy conversion devices. Thus, dielectric capacitors have become a research hotspot because of their high power density, anti cycle aging, and stable performance. Dielectric constant, but its preparation process is complex, large and not resistant to high pressure. The polymer dielectric material has good mechanical properties, easy to process and high breakdown field, but usually has low dielectric constant. Therefore, it is very important to study and prepare polymer based dielectric composites with high dielectric constant and breakdown field and low dielectric loss. In this paper, polyvinylidene fluoride (PVDF) based polymer was used as the matrix to study the size and morphology of different fillers, the effect of organic inorganic interface and organic filler on the dielectric behavior of the composite membrane. The corresponding mechanism was analyzed, the structure performance relationship was established, and the high energy storage and low loss dielectric composites were designed and prepared. The main contents are as follows: 1. SnO2 particles were prepared by hydrothermal method. The particle size 5-7 nm. was based on the percolation theory, and the SnO2/PVDF nanocomposite membrane was constructed. The dielectric constant was up to 320 under 103Hz, and the dielectric loss was less than 0.8 compared with the PVDF matrix. The dielectric behavior accorded with the percolation model and SnO2 nanoscale according to the linear fitting results. The grain has a wider band width. At the same time, the nano scale SnO2 and PVDF formed more electron scattering and potential well, and prevented the carrier transmission. It can effectively maintain a certain breakdown field strength.2. hydrothermal method to prepare sodium titanate nanotube, the diameter of 8-10 nm, the length of 300-500 nm, and polyvinylidene fluoride three fluoroethylene - three fluorine chloride The dielectric loss mechanism of the composite film is explored by a two-way and unidirectional hysteresis loop test. It is suggested that the dielectric loss of the dielectric material is formed by the external and internal conductance losses. When the test frequency is 10 Hz, the bidirectional hysteresis loop has the upward movement. It is proved that there exists between the filler and the filler and the polymer base. The external conductance loss exists between the bodies. The composite membrane is tested by one-way hysteresis loop, and the external conductance loss is not obvious at 100 Hz, but the nonlinear dielectric loss still exists. It is proved that the existence of internal conductance loss exists in the filler.3. by using the Stober method to prepare the Ag@SiO2 shell structure with different shell thickness. Packing, the size of Ag core is 40-55 nm, the thickness of SiO2 shell is 5 nm, 10 nm and 20nm. increase the interface polarization of the composite membrane because of the core shell structure of the packing, thus the dielectric constant is increased to up to 31, while the composite film keeps low dielectric loss, and the dielectric constant decreases with the increase of the SiO2 shell thickness, and the breakdown field strength increases. When a small amount of Ag@SiO2 is added, the breakdown field strength is improved and the maximum 346 MV/m. test results show that the SiO2 shell as a good insulating layer can reduce the leakage current and improve the breakdown field of the film. At the same time, the dielectric behavior of the thin film can be regulated by the thickness of the Si02 shell and the chemical peeling method of.4. has been prepared by the chemical peeling method. Boron nanoscale (BNNS) filler and composite with PVDF-TrFE-CTFE have been used to study the optimum filling amount of BNNS. When BNNS is 12wt%, the dielectric property is best and the energy release density is 7.1J/cm3. The breakdown field of the dielectric thin film is enhanced by the width of the band gap and the high breakdown field strength of BNNS, and the strength of the dielectric thin film is increased to 610 MV/m, and the addition of BNNS reduces the composite material. The grain size of the material increases the discharge efficiency (84%). On the basis of the surface modification of the nanometer barium titanate (BT), the dielectric properties of the three phase dielectric composites with BNNS and BT as filler are prepared. The dielectric properties of the three phase composite films are greatly improved by using the high breakdown field strength of BNNS and the high permittivity of barium titanate. Up to 76. when the doping amount of barium titanate is 20 wt% and the BNNS doping amount is 12 wt%, the energy release density of the three phase dielectric thin films is up to 13.3 J/cm3, and the discharge efficiency is 72%.5., and the aromatic polythiourea (ArPTU) dielectric thin film is prepared by the stepwise addition polymerization method, because of the amorphous phase polymer structure of ArPTU and the couple in the molecular chain. The ArPTU has very low dielectric loss (0.0067), high breakdown field strength (746 MV/m) and energy release efficiency (greater than 90%). The addition of ArPTU changes the crystal structure and resistivity of the composite dielectric thin film, which makes the grain size of the composite film smaller and the space between the crystal larger, which is beneficial to the PVDF-T. The free rotation of dipoles in the rFE-CTFE molecular chain reduces the hysteresis loss and increases the breakdown field strength and the energy release density. The energy release density of the composite membrane reaches 19.2 J/cm3 under the 700 MV/m electric field, while the discharge efficiency is still more than 85.

【學位授予單位】：北京化工大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TB383.2

【參考文獻】

相關(guān)博士學位論文 前1條

1 李蕊;基于PVDF的全有機介電材料制備、結(jié)構(gòu)與性能[D];武漢理工大學;2010年

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本文編號：1780022