聚酰亚胺/纳米钛酸钡复合薄膜的制备与表征

制备了一系列聚酰亚胺及其钛酸钡复合薄膜,并采用了XRD,IR等分析手段分析了复合薄膜的形貌和性能。主要研究内容如下:(1)采用水热法制备钛酸钡粉体;（2）分别用溶液混合法和原位聚合法制备PI/BT纳米复合薄膜。经分析可知,复合膜中钛酸钡粒子较为均匀地分散在聚酰亚胺基体中,并且复合膜的介电性能随钛酸钡粒子含量的增加而增加。在33%（钛酸钡的质量分数）1KHz频率时,制备的复合薄膜介电常数可达35,使其具有广泛的应用前景。     

聚酰亚胺/纳米氧化硅氧化铝杂化膜的制备

研究了用溶胶凝胶法制得的二氧化硅及三氧化二铝溶胶,将其掺入到聚酰胺酸基体中,得到SiO2-Al2O3/聚酰亚胺杂化膜,并采用FTIR、SEM和TGA表征了所制备的杂化膜的结构微观形态和热性能。结果表明,薄膜材料中SiO2和Al2O3粒子分散均匀,与有机相存在键合,材料热分解温度有所提高。     

偶联剂对聚酰亚胺/SiO_2杂化膜性能的影响

为了研究偶联剂对聚酰亚胺/SiO2杂化膜相分离及热分解温度的影响,以聚酰亚胺(HQDPA-ODA)为基体,正硅酸乙酯(TEOS)为添加剂,γ-缩水甘油丙氧基三甲氧基硅烷(GOTMS)为偶联剂,在共溶剂N,N′-二甲基甲酰胺(DMF)中,通过溶胶-凝胶法,制备出厚度约为30μm,不同SiO2质量分数的PI/SiO2杂化膜,采用傅立叶红外光谱FT-IR、热重分析TG-DTG、扫描电镜SEM等手段对膜材料的微观结构和耐热性能进行了表征。结果表明,加入GOTMS以后,SiO2粒径减小,由1 000 nm减小到200—400 nm,相分离产生的空腔结构消失,质量分数10%SiO2的杂化材料的热分解温度升高了21℃;杂化材料的热分解温度随SiO2质量分数的增加而升高。     

杂化聚酰亚胺薄膜耐电晕性能的研究

用均苯四甲酸二酐和4,4＇-二氨基二苯醚合成聚酰亚胺（PI）树脂,以甲基三乙氧基硅烷为无机前驱体原位产生二氧化硅（SiO2）粒子,并以3-氨丙基三乙氧基硅烷为偶联剂制备了PI／SiO2杂化薄膜。分析和讨论了无机成分的含量和两相间界面形态的变化对PI／SiO2薄膜耐电晕性能的影响结果表明,无机组分的引入对杂化PI／SiO2薄膜的耐电晕性能产生很大的影响,薄膜的耐电晕性能随SiO含量的增加而提高;偶联刑的引入对无机粒子的分散、两相相容性,以及界面形态具有明显的改善作用,对薄膜耐电晕性能的改善更为明显：并提出了一个耐电晕模型。     

聚酰亚胺／纳米Al2O3-SiO2和聚酰亚胺／纳米Si3N4杂化材料的结构与性能研究

将纳米Al2O3-SiO2、Si3N4分别均匀分散于聚酰亚胺（PI）前驱体聚酰胺酸中，经过热亚胺化制备了PI／纳米Al2O3-SiO2和PI／纳米鼠N4杂化材料。通过傅里叶变换红外光谱仪、X射线衍射仪、高温微量热天平、静态热机械分析仪和差示热分析仪对杂化材料的微观结构及热性能进行了研究，结果表明，杂化材料中聚酰亚胺和无机纳米粒子之间存在相互作用，形成了复合相态结构；加入纳米Al2O3，SiO2、Si3N4后杂化材料的热稳定性均高于纯聚酰亚胺，但并不完全随无机纳米粒子含量的增加而提高；与纯PI相比，在90～130℃的温度范围内PI-8％Al2O3-SiO2、PI-8％鼠Si3N4热膨胀系数分别降低了约11％和47％，加入8％纳米Al2O3-SiO2、Si3N4后杂化材料的热导率分别提高了约8％和13％。PI／纳米Al2O3-SiO2、Si3N4杂化材料不仅保留了PI原有的优异性能，而且充分发挥了纳米无机粒子对PI的特殊改性性能。     

PVA/H3PO4型二氧化硅交联杂化膜的研究

用正硅酸乙酯化学改性法制备了不同SiO2含量的PVA/H3PO4型交联杂化膜,采用X衍射仪、热重仪和多功能材料实验机表征了膜的结晶度、热稳定性、机械强度,使用交流阻抗谱和气相色谱仪研究了SiO2含量对交联杂化膜的质子导电性能和阻醇性能的影响。结果表明:正硅酸乙酯加入后,随着SiO2含量的提高,交联杂化膜的结晶度降低,热稳定性和机械性能得到了改善。质子电导率σ随SiO2含量的提高而升高,并在含量为12.50%时达到极大值,甲醇透过系数逐渐减小。     

聚酰亚胺/二氧化硅复合薄膜电学性能的研究

用均苯四甲酸二酐(PMDA)与4,4'-二氨基二苯醚(ODA)为单体,以N,N-二甲基乙酰胺(DMAC)为溶剂,通过超声机械共混法制备聚酰亚胺/二氧化硅(PI/SiO2)复合薄膜,采用红外光谱(FTIR)、扫描电镜(SEM)分别对PI复合薄膜的结构和表面形貌进行了研究表征,通过concept 80宽带介电谱测试系统对复合薄膜电学性能进行了研究。结果表明:在一定的频率下,不同无机纳米粒子含量的复合薄膜中,介电常数和介电损耗角正切随无机纳米质量分数的增加而增大。     

掺杂PST薄膜的制备与介电调谐性能研究

采用Sol-Gel法在Pt／TiO2／SiO2／Si衬底上制备了多种不同组分的（Pb0.3Sr0.7）1-xKxTiO3（PST）（x=0,1mol％,2．5mol％,5mol％）多层均匀薄膜,并研究了它们的介电调谐性能。发现掺杂后薄膜的晶粒尺寸明显减小,介电常数降低及介电损耗减小。1MHz时,随K含量的从0增加至5mol％,薄膜的介电常数从841降低至539,而介电损耗由0．134减小到0．058,其微波介电综合性能改善。     

四氟化碳等离子体处理对聚酰亚胺介电性能的影响

采用等离子体活化的方法,使用四氟化碳（CF4）气体,对印刷线路板常用基材聚酰亚胺薄膜进行了处理,将含氟基团引入到聚酰亚胺薄膜表面。通过测量材料表面的接触角、x射线光电子能谱分析等,验证了通过等离子体处理,含氟基团成功引入了聚酰亚胺薄膜表面。通过改变等离子体处理的功率及反应时间,研究了不同处理条件对聚酰亚胺薄膜介电常数和介电损耗的影响。结果显示：随着处理功率和处理时间的增加,聚酰亚胺薄膜的介电常数和介电损耗在低频区域有显著的降低（频率范围1～100Hz）。在最优条件下,聚酰亚胺薄膜的介电常数从平均2．7降至平均1．9（频率范围1～100Hz）,介电损耗正切值从平均0．145降至平均0．06左右（频率范围1～100Hz）。     

氰酸酯/聚苯醚/超支化聚硅氧烷接枝纳米SiO2复合材料的性能

以介电性能优异的聚苯醚(PPO)改性的双酚A型氰酸酯树脂（CE）为基体,分别以超支化聚硅氧烷接枝的纳米二氧化硅（HBP SiO2）和未处理的纳米二氧化硅（nano SiO2）为改性剂,制备了CE/PPO/HBP SiO2和CE/PPO/nano SiO2两种三元体系复合材料,并利用傅里叶变换红外光谱仪、差示扫描量热仪等分析手段对HBP SiO2及复合材料的结构与性能进行了研究,结果表明,nano SiO2的加入有助于提高改性体系的力学性能,且HBP SiO2比nano SiO2显示出更好的改性效果;CE/PPO/HBP SiO2体系的介电常数均低于CE/PPO/nano SiO2、CE/PPO、CE体系,而介电损耗因子比CE、CE/PPO体系的小,比CE/PPO/nano SiO2体系的大。     

Ba(Zr0.3Ti0.7)O3薄膜的结构及性能

用溶胶-凝胶法分别在Pt/Ti/SiO2/Si和LaNiO3/Pt/Ti/SiO2/Si衬底上制备了锆钛酸钡[Ba(Zr0.3Ti0.7)O3,BZT]薄膜.相结构及介电性能研究表明:衬底和薄膜厚度对BZT薄膜性能具有显著影响.制备在LaNiO3/Pt/Ti/SiO2/Si衬底上的BZT薄膜具有(100)面的择优取向,其介电常数及介电损耗则随着薄膜厚度的增加而降低.对制备在Pt/Ti/SiO2/Si衬底上的BZT薄膜,在薄膜厚度低于500nm时,其介电常数随薄膜厚度增加而增加,大于500nm时又有所减小.     

Polyimide hollow glass microspheres composite films with low dielectric constant and excellent thermal performance

Nowadays, polyimide (PI) with low dielectric constant is expected to be widely applied in microelectronics. For this reason, hollow glass microspheres (HGM) modified by silane coupling agent KH-550 (K-HGM), a series of HGM/PI and K-HGM/PI composite films with excellent thermal performance, hydrophobic and low dielectric constant were fabricated by in situ polymerization. The effect of HGM/K-HGM content on the properties of composite films was studied. The superior heat resistance of HGM can improve the thermal performance of composite films. Due to silane coupling agent KH-550, K-HGM exhibits a good interfacial compatibility with PI matrix and forms an interfacial adhesion region. With the HGM loading of 6%, comparing with pure PI films, the glass transition temperatures (T_g) of composite films were dramatically increased by 32.3°C. Especially, the low dielectric constant of 2.21 and dielectric loss of 0.0059 at 1 MHz were obtained for the PI/K-HGM composite film with addition of 8 wt%. Thus, PI/K-HGM composite films show more excellent performance. The current work provides a promising solution for fabrication of PI with low dielectric constant and superior thermal performance that may be applied in microelectronics industry.     

玻璃纤维对PTFE/SiO2复合基板材料性能的影响

采用表面改性、物料混合、压延成型、高温真空热压烧结工艺,得到了不同含量玻璃纤维(GF)增强聚四氟乙烯(PTFE)/二氧化硅(SiO2)复合基板材料,考察分析了GF含量对复合材料微观形貌、密度、吸水率、拉伸性能、压缩性能以及微波介电性能的影响情况。结果表明,随着GF含量的增加,PTFE/SiO2复合材料的密度逐渐减小,吸水率和损耗因子逐渐增大,拉伸模量、压缩模量和相对介电常数呈现出先增大后减小的趋势。当PTFE/SiO2复合材料中加入2%的GF时,复合材料具有良好的综合性能,密度为2.085 g/cm3,吸水率为0.094%,拉伸模量为1351 MPa,压缩模量为1643 MPa,相对介电常数为2.93,损耗因子为1.04×10–3。     

SiO2粒径对环氧树脂复合材料介电性能的影响

将不同粒径的SiO2微球与环氧树脂复合,制备用于直流特高压关键设备的高性能环氧绝缘复合材料,分析了其体积电阻率、介电常数与损耗,考察了SiO2微球对复合材料主要电气性能的影响;通过扫描电镜、动态热分析SiO2微球与环氧树脂的界面作用. 结果表明,不同粒径的SiO2微球均对环氧树脂复合材料性能有改善作用,添加100 nm SiO2的复合材料提升效果最显著,体积电阻率从1.87′1017 W×cm提至3.24′1017 W×cm,介电常数实部从10.99降至4.92,玻璃化转变温度从104.9℃升至106.4℃,这是因为100 nm SiO2微球表面吸附水分少、与树脂作用力强.     

介孔MCM-48粉体对环氧树脂性能影响

采用溶液共混法制备了介孔MCM-48粉改性环氧树脂复合材料,研究了MCM-48添加量对复合材料力学性能及介电性能的影响。结果表明,添加少量的MCM-48粉能够同时对环氧树脂起到增强增韧效果。复合材料1MHz下的介电常数及介电损耗均随MCM-48添加量的增加先降低后升高。当MCM-48的添加量为2%时,复合材料的综合性能最佳,弯曲强度为82.15 MPa,弯曲弹性模量为2.45 GPa,冲击强度为21.75 kJ/m2,分别比纯环氧树脂提高了27.36%、28.32%、136.59%。复合材料1MHz下的介电常数为3.55,介电损耗为0.028。该材料有望在微电子领域获得应用。     

Electrical properties of flexible graphene reinforced polyimide composites

The electrical properties of polyimide and the composite at different volumes fractions were studied in the frequency range 200–20 kHz and in the temperature range 30–200 °C. Increasing the volume fraction of graphene up to 10%, resulted in an extremely large increase in the dielectric constant, which indicates the composites remarkable ability to store electric potential energy under the effect of alternating electric field. An increase in dielectric constant was also observed with increasing temperature and decreasing frequency. The outstanding dielectric properties of polyimide graphene nanocomposites are attributed to the large volume fraction of interfaces in the bulk of the material. The measured increase in dielectric constant with increasing temperature was attributed to the segmental mobility of the polymer chains. The AC conductivity for polyimide and the composites was calculated from the loss factor and a remarkably high conductivity was obtained for the composites due to the formation of conducting paths in the matrix by the graphene sheets. Also this study showed that the thermal conductivity of the composites increased sharply with increasing graphene concentration. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45372.     

Effect of microstructure on the dielectric properties of poly(vinyl alcohol)–poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonate) composite films

Poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT–PSS) was blended with poly(vinyl alcohol) (PVA) to form 0, 10, 20, 30, 40, and 50 vol % PEDOT–PSS/PVA solutions, and their freestanding films were prepared with a simple and cost‐effective solution casting technique at 27 °C in the absence of additives. Field emission scanning electron microscopy images revealed changes in the cocontinuous network to a rodlike morphology in the composite films from 10 to 50 vol % PEDOT–PSS/PVA. The alternating‐current conductivity was found to obey Jonscher's power law. The obtained values of the dielectric constant at 27 °C were relatively high, and a maximum value of 6.7 × 10⁴ at 100 Hz for 40 vol % PEDOT–PSS'/PVA was observed. The dielectric loss attained a maximum value of about 10⁶ at 100 Hz for 40 vol % PEDOT–PSS/PVA. However, a decrease in the dielectric parameters was observed at 50 vol % PEDOT–PSS/PVA because of locally induced strain in the microstructure. The variations in polarization with respect to the applied electric field (P–E) were determined for 50, 100, and 500 Hz at 500 V for the freestanding composite films of lower concentrations up to 20 vol % PEDOT–PSS/PVA. In summary, the dielectric and P–E measurements confirmed that the electrical characteristics changed in accordance to the contribution from both resistive and capacitive sites in the PEDOT–PSS/PVA composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45079.     

High dielectric constant composites based on metallophthalocyanine oligomer and poly(vinylidene fluoride-trifluoroethylene) copolymer

Using a solution casting method, a high dielectric constant composite based on a copper-phthalocyanine (CuPc) oligomer and a poly(vinylidene fluoride-trifluoroethylene) copolymer is developed. The experimental data show that the low field dielectric constant of the composites (with 55 wt % CuPc) can reach 1000 and the loss is ∼0.5 at room temperature and 100 Hz. Because of the long-range electron delocalization in CuPc, which results in a strong space charge response of the composite to the external field, there is a strong frequency dispersion of the dielectric properties. In addition, the dielectric properties exhibit a nonlinear behavior with electric field. At a field of 10 kV/cm, the dielectric constant at 10 Hz reaches 4500; meanwhile the dielectric loss is also high. One of the unique attributes of the composite is its mechanical properties that remain very much the same as those of the polymer matrix. Even for a composite with 55 wt % CuPc (the volume fraction of CuPc in the composite is also in the similar range), the composite film is still flexible, with a Young's modulus of 1.2 GPa at room temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 70–75, 2001     

P(VDF–HFP)/BST纳米复合薄膜的制备及介电、储能性能

采用溶液铸造法,以聚(偏氟乙烯–六氟丙烯)[P(VDF–HFP)]为基体、钛酸钡锶(BST)为填料制备了纳米薄膜材料。对薄膜的物相组成和微观形貌进行了表征,研究了BST含量对薄膜介电性能和储能性能的影响。结果表明,随着BST含量的增大,薄膜的介电常数显著上升,介电损耗在中、高频区域有所下降,击穿强度逐渐减小,薄膜的充电能量密度显著增大;介电常数的实测值与Maxwell-Wagner理论模型计算值基本吻合,表明填料和基体结合良好,薄膜材料内部组织均匀,无明显缺陷。此外,从实际应用的角度讲,外加电场强度低于800 kV/cm或介于800~2100 kV/cm时,为了获得最大的放电能量密度,应分别选用BST体积分数为30%或20%的P(VDF–HFP)/BST复合薄膜材料。     

Flexible /PET/batio3/ layer–layer composite film with enhanced dielectric properties fabricated by highly loaded /batio3/ coating with acrylic resin as binder

Flexible layer–layer poly(ethylene phthalate) (PET)/BaTiO₃ composite films with enhanced dielectric permittivity were fabricated by spin coating method, consisting of PET substrate film layer and modified BaTiO₃/acrylic resin hybrid coating layer. The thickness of coating layer was less than 3 μm (about 2% of PET film thickness), and therefore, the PET/barium titanate (BT) composite films remained flexible even at high volume fraction of BaTiO₃ fillers. The volume contents of BaTiO₃ were varied from 0 to 80%, and the solid contents of BaTiO₃/acrylic resin were in the range of 51.8–72.9%. Scanning electron microscopy showed strong interaction of finely dispersed BaTiO₃ particles with acrylic resin. Morphological profile also displayed uniform coating layer of modified BaTiO₃/acrylic resin and its strong adhesion with PET film. The dielectric constant of the PET/BaTiO₃ composite films increased by about 26% at 60 vol % BaTiO₃ loading when compared with the pristine PET film, whereas the dielectric loss decreased slightly. In addition, PET‐grafted poly(hydroxylethyl methacrylate) brushes were used as substrate to introduce covalent bonding with the coating layer. Further enhancement of dielectric constant and reduction of dielectric loss were realized when compared with the composite films with bare PET substrate. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42508.