Multi-Stable Conductance States in Metallic Double-Walled Carbon Nanotubes

Electrical transport properties of individual metallic double-walled carbon nanotubes (DWCNTs) were measured down to liquid helium temperature, and multi-stable conductance states were found in DWCNTs. At a certain temperature, DWCNTs can switch continuously between two or more electronic states, but below certain temperature, DWCNTs are stable only at one of them. The temperature for switching is always different from tube to tube, and even different from thermal cycle to cycle for the same tube. In addition to thermal activation, gate voltage scanning can also realize such switching among different electronic states. The multi-stable conductance states in metallic DWCNTs can be attributed to different Fermi level or occasional scattering centers induced by different configurations between their inner and outer tubes.     

碳纳米管和石墨烯透明导电薄膜材料专利综述

通过对碳材料透明导电薄膜中的碳纳米管和石墨烯导电薄膜材料进行了技术分解,主要分为产品改进、制备方法改进以及应用,对其中产品改进和制备方法改进作了进一步细化分类,根据专利申请量,总结出主要的改进方向,同时,对重要和前沿的专利申请进行了梳理和展示,有助于国内申请人对以碳纳米管和石墨烯为主的碳材料导电薄膜领域的技术发展有较为全面的了解。     

紫外辐照对EVOH／蒙脱土纳米复合材料性能影响的研究

对蒙脱土进行有机改性,并对改性蒙脱土进行红外(FT-IR)、X射线(XRD)、扫描电镜(SEM)表征;同时采用溶液插层法制备了乙烯-乙烯醇共聚物(EVOH)/蒙脱土纳米复合膜,并对其进行不等时间的紫外辐照处理.结果表明:改性后的蒙脱土表面由亲水变为疏水;层距南1.467 nm增大到3.5 nm;而经紫外辐照处理的复合膜的力学性能、阻隔性能得到了较好的提高,同时复合膜的透明性没受到影响.     

Fabrication of Nanocomposite Powders of Carbon Nanotubes and Montmorillonite

Nanocomposite powders of carbon nanotubes (CNTs) and montmorillonite (MMT) were successfully synthesized by heating the mixed composites of polypropylene, nickel (Ni) catalyst, and organic-modified montmorillonite in large quantities after the Ni catalysts were removed. Transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and scanning electron microscopy show the co-presence of CNTs and MMT. The interlayer distance of MMT was enlarged because of the CNTs, which result in MMT being partly exfoliated and buried in the CNTs. These current nanocomposite powders of CNTs and MMT with superstructure are therefore expected to be ideal fillers for high-performance polymer nanocomposites.     

非导电聚合物／碳纳米管功能复合材料研究进展

碳纳米管具有优异的力学性能、独特的电学性能和电磁波吸收性能等,是非导电聚合物基体的理想增强材料。综述了近年来非导电聚合物／碳纳米管复合材料的制备和性能研究等情况,并讨论了今后的研究发展方向。     

Multiwalled Carbon Nanotubes/Hectorite Hybrid Reinforced Styrene Butadiene Rubber Nanocomposite: Preparation and Properties

Clay-assisted dispersion of MWCNT has emerged as a novel alternative to its conventional modification. The report deals with preparation of MWCNT/hectorite hybrid (HMH) by dry grinding method and its utilization for the reinforcement of styrene butadiene rubber (SBR). Significant improvement in tensile strength (210%) and elongation at break (42%) of SBR/HMH nanocomposite at 0.7 wt.% HMH shows its superior reinforcing efficiency. Comparison with individual fillers confirms significant synergy. Best thermal stability and dielectric response are achieved at 0.3 and 0.7 wt.% filler contents respectively. Improved properties of the nanocomposites are ascribed to enhanced level of filler dispersion and polymer-filler interaction.     

碳纳米管透明导静电涂料制备及在吸塑上的应用

比较了几种小管径碳纳米管涂膜的透光率和方块电阻,筛选出适合制备透明导静电涂料的碳纳米管TNM2。研究了碳纳米管/聚氨酯树脂涂层在不同碳纳米管含量下的透光率、方块电阻和附着力。成功制备了碳纳米管透明导静电涂料TNTC,检测了其在聚对苯二甲酸乙二醇酯(PET)塑料上凹版印刷涂布后的和涂布后不同吸塑深度下的方块电阻,并做了扫描电镜(SEM)。结果表明:碳纳米管TNM2增强了涂层的延展性,在吸塑深度达55 mm时,涂层的导电网络仍然维持通达。     

Beta/碳纳米复合分子筛膜的制备

利用浸渍提拉方法,在平均孔径500 nm的管状a-Al2O3陶瓷管载体上成功制备了无缺陷的Beta/碳纳米复合分子筛膜. 通过室温下单组分气体渗透实验,发现当Beta分子筛在聚糠醇/丙酮溶液中的含量逐渐加大时,复合膜的气体分离因数略有增加,同时气体渗透通量明显加大. 经优化后氢气渗透通量比纯碳膜增加了一个数量级,说明Beta分子筛起到了加快气体渗透通量的作用. 由SEM照片可以发现,随着Beta分子筛含量的增加,制备的纳米复合膜的厚度由平均14 mm减少到7 mm左右,从而减少了气体渗透的阻力.结合实验数据,探讨了沸石分子筛/碳复合膜气体渗透路径.     

多壁碳纳米管的改性及其复合材料的制备

用H2SO4/HNO3（体积比3∶1）对碳纳米管进行改性,结果研究表明：与原始碳纳米管相比,改性后的多壁碳纳米管的自身的分散性非常好,表面带有了更多的-OH和-COOH等官能团,碳纳米管在空气中的热稳定性明显下降,而且在碳酸氢铵与氨水和少量SDBS的混合溶液中分散稳定性更好。然后采用原位聚合的方法制备了多壁碳纳米管/碳酸铝铵复合材料,复合粉体的TEM和XRD表明改性后的多壁碳纳米管可以在碳酸铝铵粉体中进行良好的分散。     

Effect of Dispersants on the Electrophoretic Deposition of Hydroxyapatite‐Carbon Nanotubes Nanocomposite Coatings

Isopropanolic Suspensions of HA nanoparticles (20 g/L) plus various concentrations of carbon nanotubes (CNTs) were prepared using Tris and triethanolamine as dispersant. The positively charged HA nanoparticles were heterocoagulated on the negatively charged CNTs and generated the HA‐CNT composite particles with net positive surface charge. The heterocoagulation was more intensive in dispersant‐containing suspensions (DCS) due to the higher zeta potential of HA nanoparticles in them. HA‐CNTs particles can be rotated and aligned parallel to electric field as a result of torque exerted on them due to the generation of a dipole moment in CNTs during electrophoretic deposition (EPD). The mobility of HA‐CNTs particles aligned parallel to electric field is ≈50% higher than that of HA nanoparticles leading to the faster EPD from DCS when CNTs are added into them. CNTs more efficiently reinforced the coatings deposited from DCS due to the stronger electrostatic bonding between CNTs and HA nanoparticles in them.     

密度泛涵理论及其在碳纳米管性能研究中的应用

随着电子计算机技术的飞速发展,密度泛涵理论(DFT)方法在研究分子的结构与性能方面的应用日益广泛。碳纳米管是一种新型的碳纳米材料。具有独特的物理化学性质。它在储氢等方面的性能更是引起了人们的极大兴趣。这里着重介绍DFT这一重要理论及其在碳纳米管性能研究中的应用。     

碳纳米管/白炭黑/炭黑补强溶聚丁苯橡胶纳米复合材料导电性能的研究

研究碳纳米管(CNTs)/白炭黑/炭黑补强溶聚丁苯橡胶(SSBR)纳米复合材料的导电性能。结果表明,当白炭黑用量小于50份时,白炭黑的阻隔效应占主导,CNTs/白炭黑补强SSBR纳米复合材料的导电性能较差;当白炭黑用量达到70份时,白炭黑的体积排除效应占主导,复合材料的导电性能较好。炭黑和CNTs的协同作用可提高CNTs/白炭黑/炭黑补强SSBR纳米复合材料的导电性能。偶联剂Si747改性复合材料的导电性能优于未添加偶联剂Si747的复合材料。     

氧化石墨烯/炭黑/乳聚丁苯橡胶纳米复合材料的性能研究

利用乳液插层复合法制备氧化石墨烯/乳聚丁苯橡胶（ESBR）复合胶,研究其在工程机械轮胎胎面胶中的应用。结果表明：在胎面胶中加入氧化石墨烯,氧化石墨烯/炭黑/ESBR纳米复合材料的t₉₀延长;剪切储能模量和储能模量增大,玻璃化温度变化不大,损耗因子峰值减小;主要物理性能和耐磨性能提高。     

ABS/碳纳米管纳米复合材料的研究进展

综述了近年来丙烯腈-丁二烯-苯乙烯(ABS)/碳纳米管(CNTs)纳米复合材料的研究进展,介绍了该材料的不同制备方法和所得复合材料的力学、导电、雷达波吸收、热解及阻燃性能。研究发现,添加少量的CNTs可以大幅提高ABS的弹性模量、拉伸强度及模量等力学性能;降低材料的电阻率,达到永久抗静电型ABS要求;并可使材料具有雷达波吸收性能;同时还能显著改善ABS的阻燃性能。还分析了不同CNTs种类、添加量及预处理方法对ABS/ CNTs纳米复合材料上述性能的影响,并对相关机理进行了分析讨论。     

聚氨酯/碳纳米管功能复合材料的电学性能研究

采用溶液共混法制备了聚氨酯(PUR)/碳纳米管(CNTs)功能复合材料,并分别利用磁力分散和超声分散方法对CNTs进行分散,探讨了CNTs含量对PUR/CNTs复合材料电学性能的影响。结果表明,利用超声分散方法比磁力分散方法获得的CNTs在基体中的分散效果更好,并且随着超声分散时间的延长,分散效果越好;当分散时间为2 h、CNTs的质量分数为5%时,PUR/CNTs复合材料的体积电阻率趋于稳定,可以降到50 MΩ.cm,比纯PUR的体积电阻率下降了6个数量级。     

工艺参数对碳纳米管取向生长的影响

采用催化热解法,以二茂铁和二甲苯分别作为催化剂和碳源,H2和Ar作为载气,制备了定向碳纳米管阵列;考察了工艺参数对碳纳米管取向生长的影响。结果表明:在二茂铁/二甲苯溶液进入反应室的温度为310℃,H2和Ar总流速为120mL/min,抛光硅基底上容易获得定向碳纳米管阵列。     

高含量高透明度PS/TiO2纳米复合材料膜的紫外防护性能研究

采用溶剂热法非水合成了粒径小于20 nm的二氧化钛（TiO2）纳米粒子,并用硅烷偶联剂（KH 570）对纳米粒子进行原位修饰以提高粒子在聚苯乙烯（PS）的对二甲苯溶液中的分散性。采用旋涂法制备不同纳米TiO2粒子含量的PS复合材料膜,用紫外可见光光谱仪检测了薄膜的紫外防护性能。结果表明,纳米TiO2的最高含量达到95 %（质量分数,下同）;随着纳米TiO2粒子含量的增加,薄膜的紫外屏蔽性能逐渐增强,同时可见光区的透明度不会线性减少,而是趋于饱和,当纳米TiO2粒子含量达到95 %时,在人眼最敏感的550 nm波长处,依然可以获得82 %的透明度。     

碳纳米管的制备

综述了碳纳米管的几种制备工艺和相关的生长机制,还介绍了近两年来碳纳米管制备的进展情况,包括新型制备技术、特殊结构的碳纳米管制备。     

碳纳米管/聚乳酸复合材料非等温结晶动力学

研究了聚乳酸(PLA)与多壁碳纳米管(MWNTs)/PLA复合材料的非等温结晶动力学。利用硅烷偶联剂KH-550改性碳纳米管,并用溶液共混法制备MWNTs/PLA复合材料。利用DSC研究了材料的结晶过程,所得的降温曲线表明基体中的碳纳米管可以提高材料的结晶温度范围和结晶放热焓。采用Jeziorny法和Mo法研究了PLA与MWNTs/PLA复合材料的非等温结晶动力学,结果表明,适量的碳纳米管有效地起到了成核剂的作用,提高了材料的结晶速率。     

EVA/MWNTs复合材料的阻燃性能

综述了近几年来乙烯-乙酸乙烯酯共聚物/多壁碳纳米管（EVA/MWNTs）纳米复合材料的研究进展,介绍了其制备方法,详述了其热解行为及阻燃性能（包括热释放速率、引燃时间、成炭性）,并对其阻燃机理进行了深入的讨论。比较了MWNTs、有机黏土、层状双氢氧化物等不同纳米填料的阻燃性能,分析了对MWNTs进行不同处理（包括纯化、使用高密度聚乙烯进行表面涂覆改性、研磨）对相应纳米复合材料的热稳定性及可燃性的影响。