碳纳米管/粉末丁苯橡胶复合材料的热学性能

将碳纳米管(CNTs)及其它配合剂制成悬浮液,与丁苯胶乳共混,然后利用喷雾干燥法制备CNTs/粉末丁苯橡胶复合材料,检测其热学性能,并进行相应的理论分析。结果表明,随着CNTs加入量的增加,橡胶复合材料的热分解温度逐渐增加,CNTs/橡胶复合材料的热导率逐渐提高,当CNTs体积百分比含量约为22%,即CNTs加入量为60 phr时,与纯胶样品相比,复合材料的热导率提高近1倍。理论分析表明,由于CNTs自身的弯曲和缠绕以及混酸氧化对CNTs自身导热性能的破坏,复合材料热导率的实测值与理论计算值存在一定差距。     

机械混炼对碳纳米管/丁苯橡胶复合材料的影响

为研究机械混炼对碳纳米管(CNTs)/粉末丁苯橡胶(SBR)复合材料性能的影响,从而获得性能优异的CNTs/SBR复合材料,联合采用喷雾干燥法和机械混炼法,制备高填充量CNTs/SBR复合材料.将喷雾干燥法制备的CNTs/粉末SBR复合材料在开炼机上机械混炼,对比分析混炼前后试样的物理和力学等相关性能,并对其微观形貌进行检测.结果表明,机械混炼使CNTs获得进一步的分散,与SBR基体间作用力得到增强,与混炼前相比,混炼后试样的玻璃化转变温度、交联度和常规力学性能均得到提高,当CNTs加入量为50phr时,混炼后复合材料的拉伸强度和撕裂强度分别为13.1MPa和39.8kN/m,比混炼前试样分别提高了约80%和20%.     

超声分散制备天然橡胶/丁苯橡胶/炭黑/碳纳米管纳米复合材料

通过超声分散制备了分散均匀的碳纳米管(CNTs)/天然橡胶母料,利用母料制备了天然橡胶(NR)/丁苯橡胶(SBR)/炭黑(CB)/碳纳米管复合材料。通过比较常规搅拌、双辊混炼和超声分散三种方法对碳纳米管的分散及对复合材料性能的影响,表明超声分散能实现碳纳米管在基体中均匀分散,CNTs和CB的协同作用提高了复合材料的力学性能,当CB/CNTs之比为37/3时力学性能最高,与未加CNTs增强的体系相比,拉伸强度提高了6.4%。当CNTs含量为7phr,与未加CNTs的体系相比,压缩模量提高了20%。     

掺入碳纳米管提高聚苯乙炔的导电性研究

用AlCl3作催化剂制备了聚苯乙炔（PPA），采用共混法制备了碳纳米管（CNTs）与PPA的复合材料，并进行了导电性能测试，结果表明，当CNTs含量增加时，复合材料的电导率升高，CNTs含量为3%时是复合材料导电的临界浓度，当CNTs含量达25%时复合材料达极限电导率，比纯的PPA的电导率提高了13个数量级。CNTs/PPA复合材料的导电机理符合导电通道理论。     

碳纳米管/炭黑协同效应对天然橡胶/顺丁橡胶复合材料性能的影响

使用两种一定比例的填料,在增加碳纳米管(CNTs)的同时不等量的减少炭黑(CB),其比例为m(CNTs):m(CB的减少量)=1:2.5,研究填料的变化对橡胶的力学等性能的影响。用扫描电镜(SEM)观察橡胶脆断面碳纳米管的分散情况,在3D测量激光显微镜下观察了橡胶拉伸断面的平整度和高度差。结果表明,填充4 phr CNTs时拉伸强度最高,比添加0 phr的高11.41%;随着CNTs的增多炭黑的减少使材料的加工性能变差,模量和耐磨性提高,填充8 phr CNTs的橡胶比0 phr的耐磨性高21.14%;根据动态力学性能测试(DMA)的损耗因子,随着碳CNTs添加量的增多橡胶的滚动阻力减小,但是抗湿滑性变差。     

纤维素纳米纤丝-碳纳米管/天然橡胶柔性导电弹性体的合成与性能

利用纤维素纳米纤丝(Cellulose nanofibers,CNFs)搭载碳纳米管(Carbon nanotubes,CNTs)均匀分散在天然橡胶(Natural rubber,NR)基体中,制备了具有高强度和高柔韧性的复合导电弹性体(CNF-CNT/NR)。通过对其化学结构、微观结构、力学性能和电学性能等研究发现,CNFs能有效协助CNTs在NR基体中均匀分散,使得弹性体的力学性能和电学性能显著提高。当CNFs和CNTs含量分别为3和10 phr时,CNF-CNT/NR的强度和弹性模量可达6.44±0.32 MPa和8.77±0.48 MPa,约为纯NR的6.9和9.96倍,CNT/NR的1.49和1.59倍;其电导率可达1.78±0.86 S/m,在电流密度为0.3 A/g时比电容可达107 F/g;1.0 A/g的电流密度下循环充放电1 200次,其比电容仍为初始值的83%。该柔性导电弹性体具有优良的机械性能和电学性能,有望应用于柔性电子器件领域。     

碳纳米管/聚苯乙烯复合材料的制备及导电性能研究

用溶液共混的方法将碳纳米管(CNTs)分散在聚乳酸聚己酸内酯(PLLA-PCL)嵌段共聚物中,再采用熔融共混的方法,制备了CNTs/PLLA-PCL/PS复合材料.扫描电镜和高分辨率光学显微镜观察发现,CNTs能够较均匀地分散在PLLA-PCL.电导率的测定表明,CNTs的加入大幅度提高了聚苯乙烯的导电性能,与CNTs//PS复合材料相比,PLLA-PCL的加入对更加有效地分散CNTs.     

改性累托石粉体的制备及其填充橡胶复合材料的结构与性能

利用喷雾干燥法制备了硅烷偶联剂KH550改性的累托石粉体, 考察了喷嘴进口温度对制备的累托石粉体表面性质、结构及形貌的影响。将累托石粉体分别加入到丁苯橡胶(SBR)、天然橡胶(NR)和丁腈橡胶(NBR)中, 通过熔融共混法制备了改性累托石/橡胶复合材料, 研究了累托石在橡胶基体中的分散状态及其对基体的增强效果。结果表明: 随着进气温度的提高, 与累托石复合的KH550的量也随之增加; KH550分子插层进入累托石层间, 阻碍了片层的再聚集, 片层堆砌更加无序蓬松; 改性累托石在SBR中出现了局部团聚现象, 在NBR中分散较均匀, 而在NR中分散状态最好; 与相应的纯橡胶相比, 改性累托石填充的SBR和NBR基复合材料的各项力学性能均有所提高, 而其填充的NR基复合材料的定伸应力提高, 拉伸强度和撕裂强度基本不变, 断裂伸长率有所下降。     

静电组装法制备CB/CNTs复合材料及性能表征

用阴、阳离子表面活性剂分别对炭黑(CB)、碳纳米管(CNTs)进行表面修饰,使其分别带负电荷和正电荷,并采用超声波分散仪对其进行分散处理。探讨了添加几种不同分散剂超声分散的效果。利用相反电荷相互吸引原理,将带有负电荷的CB和正电荷的CNTs,进行静电组装形成具有优良性能的CB/CNTs导电材料。结果表明:表面活性剂可以使CB、CNTs表面附有相应电荷,可以有效分散CB、CNTs。利用静电组装法制得CB/CNTs复合材料,且导电性能得到良好改善。     

CB/CNTs/PP导电高聚物力/温度作用下介电性能的研究

以聚丙烯(PP)为基体,炭黑(CB)和碳纳米管(CNTs)为填料,通过熔融共混、注塑成型制备导电复合材料,测定电场频率、填料种类、填料含量以及温度、载荷等因素对其介电性能的影响。结果表明,室温下,随着填料含量的增加,材料介电常数和介电损耗均呈增大趋势;随着频率的增加(100 Hz～10MHz),介电常数和介电损耗首先迅速降低,然后逐渐趋于稳定;随着CNTs的加入,CB/CNTs/PP导电复合材料的介电常数明显增大,但是当填料含量达到某一定值时,继续增大CNTs的含量,介电常数反而下降;同一频率下,随着温度的升高(30～100℃),由热膨胀引起炭黑粒子间距的变化会导致介电常数减小。复合材料压缩实验表明:压缩载荷作用下,材料发生形变,基体中的CB粒子间相对位置改变,引起介电常数减小。     

Preparation and properties of the powder SBR composites filled with CNTs by spray drying process

Carbon nanotubes (CNTs) filled powder styrene-butadiene rubber (SBR) composites were prepared by spray drying of the suspension of CNTs in SBR latex. The powder was spherical like and uniform with an average diameter of less than 10 μm. The dispersion of CNTs in the rubber matrix was improved remarkably compared with that in the rubber composites obtained by the conventional mechanical mixing method. Further study about the effect of CNTs on the prepared SBR composites was performed by analyzing the vulcanization process of the SBR powder, thermal and mechanical properties of the vulcanized SBR composites. Differential scanning calorimeter (DSC) analysis indicated that the glass transition temperatures of SBR composites increased with the increasing ratio of CNTs. The vulcanization process showed that CNTs could decelerate the vulcanization of the SBR composites. Dynamic mechanical analysis indicated that the storage modulus of the composites was improved with the CNTs additions, especially when the CNTs addition exceeded 30 phr. Compared with pure SBR composites, the hardness, tensile and tear strengths of the composites filled with 60 phr CNTs enhanced 73.9%, 327.7% and 191.1%, respectively, which should be ascribed to the excellent mechanical properties of CNTs and uniform dispersion of CNTs in the rubber matrix.     

Preparation and properties of powder styrene-butadiene rubber composites filled with carbon black and carbon nanotubes

Carbon nanotubes (CNTs) and carbon black (CB) filled powder styrene-butadiene rubber (SBR) composites were prepared by spray drying of the suspension of CNTs and CB in SBR latex. The powders were sphere like and fine with uniform diameters of 10-15 μm. Experimental results showed that the introduction of CNTs into the matrix was beneficial to improve the security of the vulcanization of the rubber composites, and the dynamic and basic mechanical properties of the CNTs/SBR composites were better than those of CB/SBR and neat SBR composites. Observations on the microstructure of the composites indicated that CNTs were well dispersed in the matrix. Morphology of the fracture confirmed that the bonding between CNTs and rubber matrix was strong and load can be transferred to CNTs efficiently during the mechanical property tests. Moreover, the powder SBR composites containing well-dispersed CNTs could be perfect candidate as additives for other polymers.     

Styrene butadiene rubber/aluminum powder composites—mechanical,morphological and electrical behaviors

Different weight fractions of aluminum (Al) powder viz., 10, 20, 30, 40, 50, 60 and 70 phr were incorporated into styrene butadiene rubber (SBR) matrix. The Al powder filled and vulcanized SBR composites have been characterized for mechanical properties such as tensile strength, tensile modulus and surface hardness. A drastical improvement in tensile strength and tensile modulus with increase in filler content of the composites was noticed. The electrical properties such as dielectric constant, tan delta and dielectric loss were measured for all the four compositions. The effect of volume fraction (0–70 phr) of conducting filler, frequency (100 kHz–30 MHz), temperature (25–75°C) and relative humidity on dielectric constant, dielectric loss and tan delta values of the composites were studied.     

New Fabrication and Mechanical Properties of Styrene-Butadiene Rubber/Carbon Nanotubes Nanocomposite

A novel technology to prepare styrene-butadiene rubber(SBR)/carbon nanotubes(CNTs) composites was developed by combining a spray drying method and a subsequent mechanical mixing process.The cross-linking degrees of the vulcanized composites increased gradually with the additive CNTs contents.By comparing with those of the pure SBR composites,the mechanical properties such as tensile strength,tear strength and hardness of the composites filled with CNTs at certain contents were dramatically improved almost b...     

High electrical performance of carbon nanotubes/rubber composites with low percolation threshold prepared with a rotation-revolution mixing technique

The present study demonstrates a novel mixing approach for achieving a good dispersion of carbon nanotubes (CNTs) in a styrene-butadiene rubber (SBR), which leads to a significant improvement in electrical properties. Our mixing technique consists of (1) pretreatment by ultrasonication to disentangle the bundles of CNTs in organic solvent and (2) “rotation-revolution” mixing of the CNTs with SBR without mechanical shear, which prevents CNTs from collapsing during the mixing process. The present mixing method does not require the addition of any dispersing agents (amphiphilic molecules) or chemical modification of the CNTs to obtain a good dispersion. Compared with a conventional Banbury mixing technique, our method leads to a significant decrease in the percolation threshold (less than 1 phr), where the electrical conductivity suddenly increases due to the formation of percolation networks of CNTs in SBR. This is because the aspect ratio of the CNTs was maintained even after the mixing process, whereas CNTs were broken during the conventional Banbury mixing. The effect of using different types of CNTs on electrical conductivity was also investigated. The results show that the percolation threshold is largely related to the structural quality (graphitization) of the CNTs as well as their aspect ratio.     

氮化铝/氮化硼/碳纳米管/硅橡胶复合材料的力致填料取向对导热性能的影响

随着科学技术的发展,电子元器件发热量大幅度增加,因此开发兼具高导热和高绝缘性能材料日益迫切。以甲基乙烯基硅橡胶（SR）为基体,碳纳米管（CNTs）、六方氮化硼（BN）以及氮化铝（AlN）为导热填料,通过机械共混法制备导热复合材料。研究3种导热填料复配对复合材料的导热性能、绝缘性能和力学性能的影响,研究填料取向对复合材料导热性能的影响,研究材料表面温升与加热时间的关系。采用Agari模型预测复合材料的理论热导率。通过热红成像、扫描电子显微镜、X射线衍射分析、热重分析等对复合材料进行表征。结果表明：随着复配导热填料中AlN用量的减少,BN和CNT_S用量的增加,复合材料的热导率逐渐升高;当AlN为80 phr,BN为68 phr,CNTs为2 phr时,复合材料的垂直热导率为1.857 W·m^-1·K^-1,平行热导率为2.853 W·m^-1·K^-1,体积电阻率为2.18×10¹² Ω·cm,拉伸强度达4.3 MPa,复合材料的综合性能较好。     

Mechanical performance of styrene-butadiene-rubber filled with carbon nanoparticles prepared by mechanical mixing

Reinforcement of styrene-butadiene-rubber (SBR) was investigated using two different carbon blacks (CBs) with similar particle sizes, including highly structured CB and conventional CB, as well as multi-walled carbon nanotube (MWCNT) prepared by mechanical mixing. The attempts were made to examine reinforcing mechanism of these two different classes of carbon nanoparticles. Scanning electron microscopy and electrical conductivity measurement were used to investigate morphology. Tensile, cyclic tensile and stress relaxation analyses were performed. A modified Halpin-Tsai model based on the concept of an equivalent composite particle, consisting of rubber bound, occluded rubber and nanoparticle, was proposed. It was found that properties of CB filled SBR are significantly dominated by rubber shell and occluded rubber in which molecular mobility is strictly restricted. At low strains, these rubber constituents can contribute in hydrodynamic effects, leading to higher elastic modulus. However, at higher strains, they contribute in stress hardening resulting in higher elongation at break and higher tensile strength. These elastomeric regions can also influence stress relaxation behaviors of CB filled rubber. For SBR/MWCNT, the extremely great inherent mechanical properties of nanotube along with its big aspect ratio were postulated to be responsible for the reinforcement while their interfacial interaction was not so efficient.