微胶囊化石墨烯/硅橡胶泡沫电介质材料的制备及介电行为

以苯乙烯马来酸酐共聚物(SMA)为乳化剂、三聚氰胺甲醛树脂(密胺树脂,MF)为壁材、片状石墨烯(GE)为芯材,通过原位聚合法制备了包覆的石墨烯“微胶囊”,并以微胶囊作为填料,双组分室温硫化泡沫硅橡胶(RTVSR)作为基体,通过室温硫化(RTV)硅橡胶制备具有泡孔结构的电介质复合材料。提出了对石墨烯进行微胶囊化包覆的制备新工艺,讨论了超声分散功率、石墨烯与壁材的用量比例对微胶囊形貌和包覆效果的影响,并比较了包覆前后、发泡前后电介质复合材料的介电性能。研究结果表明,石墨烯与壁材质量比为1∶100、超声功率为840 W时制备的分散液较稳定、石墨烯的表面附着物较多;同时包覆(微胶囊化)能减少石墨烯发生团聚,0.3 g微胶囊填量下,包覆后的微胶囊石墨烯/泡沫电介质材料的介电常数是包覆前石墨烯/硅橡胶电介质材料的2.45倍,而介电损耗比石墨烯/硅橡胶复合材料还低,只有0.002,同时泡孔的存在有利于提升复合材料的介电性能。     

新型石墨烯/硅橡胶纳米复合电介质泡沫材料的制备及介电性能评价

通过室温硫化(RTV)法制备了不同泡孔直径的石墨烯/有机硅橡胶泡沫复合材料。提出了一种制备不同发泡倍数的双组分室温硫化加成型有机硅橡胶泡沫复合材料的工艺;讨论了石墨烯含量、发泡倍数、泡孔的数目和尺寸对室温硫化硅橡胶泡沫介电性能的影响。结果表明,在同一发泡倍数下,介电常数随石墨烯的添加量增加而增加,达到阈值后降低;在同一石墨烯添加量下,泡孔尺寸和泡孔数目有着不同贡献:直径、泡孔数目较少时,介电常数降低,泡孔的总数和大孔的占比较多时,介电性能最佳。此外含有石墨烯的有机硅橡胶泡沫复合材料较纯硅橡胶泡沫而言,其介电常数提升了6倍左右,同时保持着较低的介电损耗。     

碳纳米管/酞菁铜纳米复合材料的制备及结构性能表征

用微波辐照法合成了羧基酞菁铜,与羟基化碳纳米管进行溶液混合,并利用TEM、XRD、FTIR等研究了碳纳米管/酞菁铜复合材料的形态结构,同时测试了不同频率下复合材料的导电性和介电性能,并对复合材料在有机溶剂中的分散性进行了观察。结果表明,在碳纳米管表面上成功包覆了一层羧基酞菁铜,复合材料表面仍保留有大量的羧基活性基团,复合材料呈现出半导体性质,导电率随频率没有明显的变化,复合材料的介电常数随频率减小而增加,在10 Hz时复合材料的介电常数高达816,包覆有酞菁铜的碳纳米管在有机溶剂中的分散性也得到极大的提高,这为原位聚合法或溶液聚合法制备高介电聚合物基复合材料提供了可行性。     

碳纳米管/酞菁铜纳米复合材料的制备及结构性能表征

用微波辐照法合成了羧基酞菁铜,与羟基化碳纳米管进行溶液混合,并利用TEM、XRD、FTIR等研究了碳纳米管/酞菁铜复合材料的形态结构,同时测试了不同频率下复合材料的导电性和介电性能,并对复合材料在有机溶剂中的分散性进行了观察。结果表明,在碳纳米管表面上成功包覆了一层羧基酞菁铜,复合材料表面仍保留有大量的羧基活性基团,复合材料呈现出半导体性质,导电率随频率没有明显的变化,复合材料的介电常数随频率减小而增加,在10 Hz时复合材料的介电常数高达816,包覆有酞菁铜的碳纳米管在有机溶剂中的分散性也得到极大的提高,这为原位聚合法或溶液聚合法制备高介电聚合物基复合材料提供了可行性。     

不同功能化碳纳米管对聚醚醚酮阻燃性能的影响

以聚醚醚酮(PEEK)为基体,碳纳米管(MWNTs)、羟基化碳纳米管(MWNTs-OH)、羧基化碳纳米管(MWNTs-COOH)为添加剂,通过熔融共混、模压成型的方法制备了3种不同的PEEK/MWNTs复合材料,通过热重分析法、锥形量热法对复合材料的热稳定性、阻燃特性进行研究。结果表明:纯聚醚醚酮材料比碳纳米管/聚醚醚酮试样容易点燃;羧基化碳纳米管/聚醚醚酮试样相比于其他的试样拥有更低的平均释放速率和热释放速率峰值(PHRR),PHRR较单纯的聚醚醚酮降低了16%;初始氧化温度达到507℃,具有较好的热稳定性。     

微胶囊APP复配碳材料对EP阻燃和导电性能影响

以环氧树脂为壁材,聚磷酸铵(APP)为核,通过原位聚合的方式制备出微胶囊包覆聚磷酸铵(EAPP)。同时复配纳米碳材料(碳纳米管和石墨片),制备环氧树脂复合材料,研究了复合材料的阻燃和导电等性能。结果表明:经微胶囊包覆后的APP在环氧树脂基体中的分散性得到改善,复合材料的阻燃性能也得到提高。当100g环氧树脂添加10g EAPP及3g碳纳米材料时,复合材料的氧指数提高至28.6%,电导率提高至6.61×10-3S/cm,达到导电级别。     

碳纳米管／环氧树脂复合体系研究

采用熔融混合法,利用超声分散制备了碳纳米管／环氧树脂纳米复合材料。研究了羟基化碳纳米管的添加量对复合材料的反应活性的影响;同时测试了碳纳米管／环氧树脂纳米复合材料的弯曲性能和电性能,并利用透射电镜对碳纳米管在复合材料中的微观结构进行了表征。结果表明：碳纳米管使复合材料的反应活性有所提高;当碳纳米管含量为1％时,碳纳米管／环氧树脂复合材料的弯曲强度和弯曲模量分别由纯体系的143．32MPa和3563．76MPa提高到155．79MPa和3690．45MPa,碳纳米管在环氧树脂基体中呈单根分散。碳纳米管使复合材料的体积电阻率和表面电阻率下降2个数量级。     

高介电常数及低介电损耗的环氧树脂/包覆碳纳米管的制备及研究

主要研究包覆碳纳米管对环氧树脂介电性能的影响。三聚氰胺甲醛树脂原位聚合对碳纳米管进行包覆,在碳纳米管表面形成高分子绝缘层使其在填充过程中不易相互导通。将包覆碳纳米管按不同包覆比加入环氧树脂,制备环氧树脂/包覆碳纳米管复合材料。当包覆碳纳米管与环氧树脂的包覆比为1∶10,制得的复合材料在1 kHz时介电常数为117,是纯环氧树脂的16.7倍,但介电损耗为0.052,较纯环氧树脂增加了44.4%。     

羧基化多壁碳纳米管对T-1000碳纤维/环氧树脂复合材料性能的影响

对多壁碳纳米管进行了表面羧基化处理,将羧基化碳纳米管添加到环氧树脂基体中,通过湿法缠绕工艺制备出具有高性能的T1000碳纤维增强环氧树脂复合材料。结果表明,复合材料的界面性能和耐热性能得到改善,当羧基化碳纳米管质量含量为1％时,复合材料的层间剪切强度提高了近29％。     

泡沫/实体交替层状硅橡胶材料的构筑与力学性能

使用羟基硅油作为结构控制剂调节硅橡胶的弹塑性,并采用超临界二氧化碳发泡构筑了泡沫/实体交替层状硅橡胶材料,对该材料的泡孔结构和层结构进行了表征,研究了泡沫/实体交替层状结构对硅橡胶泡沫力学性能的影响。结果表明,当硅橡胶中羟基硅油含量为1份(质量,下同)(实体层)、7份(泡沫层)时,制备出泡沫/实体交替层状硅橡胶材料,该材料较普通硅橡胶泡沫具有更小的泡孔尺寸(2.3μm),其泡沫层具有更高的泡孔密度(1.44×10~(10)个/cm~3)、更高的拉伸强度(5.09 MPa)和更好的抗压缩性能。     

Mechanical,dielectric, and magnetic properties of the silicone elastomer with multi‐walled carbon nanotubes as a nanofiller

Silicone elastomer and multi‐walled carbon nanotubes (MWCNTs) composites, applicable as actuators and controllable dampers, were studied. Dynamic mechanical analysis (DMA) and vibrating sample magnetometry (VSM) were used to investigate the mechanical and magnetic properties of silicone elastomers and MWCNTs composites. Also, measurement of their dielectric property was conducted. The addition of MWCNT was able to tailor the damping and dielectric properties of the silicone elastomer. In this study, a 0.7 wt% of MWCNT composite demonstrated an attractive condition for the damping and the dielectric property. Exceedingly, the modulus increased with the application of a magnetic field. The good filler effect with the small addition of the MWCNTs content is caused by their unique structure, catalytic effect, and magnetic property. POLYM. ENG. SCI., 47:1396–1405, 2007. © 2007 Society of Plastics Engineers     

Effect of KH550 on the Preparation and Compatibility of Carbon Fibers Reinforced Silicone Rubber Composites

Silicone rubber has good heat resistance, but its mechanical properties are poor. To improve the mechanical properties of the silicone rubber, the carbon fiber / silicone rubber composites were prepared in this paper, in which the silicone rubber was used as the matrix, the high-performance carbon fiber (CF) treated with coupling agent is used as the reinforcement. The best composite formulation, the types and content of coupling agent are determined by testing mechanical properties of the composites. The morphology structures of the composites were observed by scanning electron microscope (SEM), the compatibility between carbon fiber and silicone rubber was studied by infrared spectrum analysis (IR), dynamic thermal mechanical analysis (DMA) and X-ray photoelectron spectroscopy (XPS). The results show that the best composite formulation is silicone rubber of 100 phr, carbon fiber of 12 phr, coupling agent KH550 of 2.5 phr. The best first curing conditions are at 175 ^°C under 10 MPa for 30 min, the postcuring conditions are at 200 ^°C for 2h. The compatibility between carbon fiber treated with KH550 and silicon rubber is the best by SEM, IR, DMA and XPS analysis, and confirm that the coupling agent KH550 plays a compatilizer role in the preparation process of the carbon fiber/silicone rubber composites.     

一维多壁碳纳米管增强丁基橡胶/聚丙烯热塑性弹性体复合材料的相态结构及热电性能研究

制备一维多壁碳纳米管(MWCNTs)增强丁基橡胶(IIR)/聚丙烯(PP)动态硫化热塑性弹性体(TPV)复合材料,研究IIR/PP用量比(简称橡塑比)对复合材料相态结构、介电性能、导热性能和物理性能的影响。结果表明:复合材料呈现“海-岛”相结构,IIR相以微米级交联颗粒分散在PP相中;MWCNTs主要分散在PP中,随着橡塑比的增大,MWCNTs有少量团聚现象;随着橡塑比的增大,复合材料的交流电导率、介电常数和热导率增大,且橡塑比大于6/4时增速减小;随着橡塑比的减小,复合材料的拉伸强度先增大后减小;当橡塑比为5.5/4.5时,复合材料的物理性能较好。     

Development of a processing method for carbon nanotubes modified fluorosilicone rubber with enhanced electrical,dielectric, and mechanical properties

ABSTRACT

The multiwall carbon nanotubes/fluorosilicone rubber composites (S-x composites) are prepared by a solution-coagulation method. Compared with the composites (D-x composites) fabricated by the traditional direct mechanical mixing method, S-x composites show the obvious enhanced electric and dielectric performances. The percolation thresholds are estimated to be 1.39 vol% for D-x composites and 0.74 vol% for S-x composites, respectively. S-1.1 composite exhibits high dielectric permittivity (2120) at 1 kHz, which is about 50 times higher than that of D-1.1 composite. Furthermore, the mechanism of the S-x composites with outstanding dielectric properties is investigated.     

Enhanced dispersion of carbon nanotube in silicone rubber assisted by graphene

We report a novel, scalable and inexpensive approach to fully disperse carbon nanotubes in silicone rubber by the addition of graphene. In comparison to graphene, the dispersion of multi-walled carbon nanotubes (MWNTs) in silicone rubber matrix is extremely difficult although both of them possess similar physical structure. The different dispersion behavior of graphene and MWNTs could be contributed to the difference in their interaction with polymer matrix and their geometry. Based on SEM, TEM and XRD analysis, we find that the dispersion of MWNTs in silicone rubber is dramatically improved by the addition of graphene. Graphene acts as a compatilizer since it shows strong interaction with both polymer matrix and MWNTs. This method provides a simple route to enhance the dispersion of carbon nanotubes and improve the electrical property of the polymer composites. The synergic effect of the hybrid materials may not to be limited to the applications in polymer composites.     

Influence of carbon‐based nanofillers on the electrical and dielectric properties of ethylene vinyl acetate nanocomposites

A comparative study of ethylene vinyl acetate nanocomposites based on expanded graphite, multiwalled carbon nanotubes, and carbon nanofibers has been carried out to investigate the effect of different carbon nanofillers on the electrical properties of the corresponding composites. The composites were prepared by ultrasonic dispersion of fillers in ethylene vinyl acetate solution, followed by casting and compression molding. The dependence of AC conductivity and dielectric constant on the frequency and filler concentration was investigated. Carbon nanofibers provided maximum conductivity as well as lowest percolation threshold (8.2 vol%) compared to expanded graphite and multiwalled carbon nanotubes filled composites. The improvement in both electrical conductivity and dielectric constant was attributed to the high filler aspect ratio and the formation of conducting networks. The relationship of dielectric constant with filler volume fraction for all the composite systems is estimated using a power law. The pressure sensing capability of the composites at respective percolation thresholds was also compared. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

碳纳米管／Al2O3／硅橡胶导热复合材料结构和性能的研究

将碳纳米管混入Al2O3 /硅橡胶复合材料中,制得了导热硅橡胶复合材料并对其进行了研究。结果表明：随着碳纳米管用量的增加,材料导热性能逐渐增加;碳纳米管有助于填料网络结构的形成．达到了协同增加导热性能的效果;原预想碳纳米管在体系中伸展后能形成导热通路,可大幅提高导热效率．但由于开炼共混时未能保存住其高长径比的特点,增益效果不够显著。     

DMC/MVQ绝缘复合材料的制备及性能表征

针对硅橡胶力学性能差的特点,本工作以硅橡胶（MVQ）为基相,以团状模塑料（DMC）为增强相,以丁苯橡胶（SBR）为相容剂来制备DMC/MVQ绝缘复合材料,研究了SBR的用量对MVQ性能的影响。结果表明：SBR和MVQ共混制得的并用胶性能要比纯MVQ的性能好,其最佳配比为DMC 60phr,SBR 25phr,MVQ 75phr;制备的复合材料体积电阻率都在4.9×1012Ω.m以上,复合材料的绝缘性能良好;通过扫描电镜分析（SEM）和动态热机械分析（DMA）,研究了复合材料的相容性,SBR的加入改善了DMC/MVQ绝缘复合材料的相容性,增加了界面相互作用,提高了DMC/MVQ绝缘复合材料的性能。     

纳米无机粒子补强天然橡胶的研究 (Ⅳ)碳纳米管/天然橡胶复合材料的研究

碳纳米管具有非常大的长度-直径比率,是复合材料中理想的增强型纤维,从理论上讲完全可以制造出更高强度、更高密度、具有导电性的复合材料,表现出优异的补强天然橡胶的性能.本文综述了碳纳米管的制备技术、改性以及补强橡胶的研究进展.