高性能环氧树脂/碳纳米管复合物的热分析研究

用差示扫描量热仪(DSC)、热失重分析仪(TGA)和动态力学热分析仪(DMTA)研究了多壁碳纳米管(MWNTs)/高性能4,4′-二氨基二苯甲烷四缩水甘油环氧树脂(TGDDM)/4,4′-二氨基二苯基砜(DDS)复合物的热性能.Kissinger和Flynn-Wall-Ozawa的非等温固化动力学研究发现,随着MWNTs含量的增加,复合物固化反应的活化能先减小后增大.TGA研究表明,MWNTs的添加对环氧树脂热稳定性影响很小.碳纳米管填充到TGDDM/DDS体系后,复合物的储存模量随着MWNTs含量的增加而增大,而玻璃化温度却随之减小.     

原位缩聚法制备碳纳米管/尼龙11复合材料

用原位缩聚法制备了碳纳米管增强的尼龙11复合材料,用X射线衍射仪、红外(FTIR)、扫描电镜(SEM)、热重(TGA)、机械拉伸测试仪等对其结构、形貌、热性能及机械性能进行了表征测试.扫描电镜结果显示碳纳米管均一地分散在尼龙11/碳纳米管复合材料中.复合材料的拉伸模量比纯尼龙11有较大的提高.当复合材料中碳纳米管含量分别为1%,5%,10%时,材料的拉伸模量分别提高了34.5%,92.9%和113,7%.同时,复合材料的储能模量也有提高.热分析结果显示当复合材料中碳纳米管含量为1%时,其失重5%和10%的温度分别由纯尼龙11的404℃、424℃提高到414℃和437℃.示差扫描量热分析(DSC)显示复合材料的结晶温度随碳纳米管的加入而升高,而结晶度则降低.     

Polymorphism of nylon‐6 in multiwalled carbon nanotubes/nylon‐6 composites

The effects of pristine and amino‐functionalized multiwalled carbon nanotubes (MWNTs) on the crystallization behaviors of nylon‐6 were investigated by differential scanning calorimetry and X‐ray diffraction. The results indicate the presence of polymorphism in nylon‐6 and its composites, which is dependent on the MWNTs concentration and the cooling rate. More MWNTs and slow cooling from the melt favors the formation of α crystalline form. With the increase in cooling rates, the crystallinity of neat nylon‐6 decreases, and that of the composites decreases initially but increases afterward. Moreover, the degree of crystallinity of the composites is higher than neat nylon‐6 under high cooling rates, counter to what is observed under low cooling rates. The heterogeneous nucleation induced by MWNTs and the restricted mobility of polymer chains are considered as the main factors. Furthermore, addition of MWNTs increases the crystallization rate of α crystalline form but amino‐functionalization of MWNTs weakens this effect. The influence of thermal treatment on the crystalline structure of MWNTs/nylon‐6 composites is also discussed. A γ–α phase transition takes place at lower temperature for MWNTs/nylon‐6 composites than for nylon‐6. The annealing peaks of the composites annealed at 160 °C are higher than that of neat nylon‐6, and the highest annealing peak is obtained for amino‐functionalized MWNTs/nylon‐6 composites. This phenomenon is closely related to the different nucleation and recrystallization behaviors produced by various MWNTs in confined space. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1499–1512, 2006     

多壁碳纳米管填充高密度聚乙烯复合材料的导电特性

自20世纪90年代Iijima发现碳纳米管(Carbon nanotubes,CNTs)以来,由于其独特的力学性能、电学性能和极高的纵横比,使CNTs在纳米电子器件、催化剂载体、电极材料、储氢材料等方面的应用取得了引人注目的进展,迄今,CNTs填充高分子复合材料的研究主要集中在力学增强以及光学性能的改进方面,其制备方法主要是溶液法和原位聚合方法,     

ZnO纳米线基MWNTs/PVDF复合热电材料的制备及特性研究

将不同比例的多壁碳管(MWNTs)与聚偏二氟乙烯(PVDF)聚合物混合后,喷涂于n型ZnO半导体纳米线阵列上,制备了一种新型ZnO纳米线基MWNTs/PVDF热电复合材料.与以往采用价格昂贵的p型与n型单壁碳纳米管(SWNTs)与聚合物混合制备的复合热电材料特性相比,这种新型热电复合材料在降低制造成本的同时,利用分散于聚合物中MWNTs的一维电子传输特性及形成的大量界面势垒,加上ZnO半导体纳米线具有的较高载流子密度与迁移率,提高了复合热电材料中电子的输运特性,增加了材料对声子的散射强度.测试发现,在一定的温度梯度下,随着MWNTs添加质量百分比的增加,热电材料的温差电动势和电导率也随之增加,但其Seebeck系数变化量不大.研究表明,这种热电材料有望替代采用p型与n型SWNTs构建的SWNTs/PVDF复合热电材料.研究结果对开发超轻、无毒、廉价、可应用于各种微纳电子领域的新型电源具有重要的参考价值.     

Thermal degradation behavior of multi-walled carbon nanotubes/polyamide 6 composites

This paper focuses on the thermal degradation behavior of multi-walled carbon nanotubes (MWNTs)/polyamide 6 (PA6) composites under air and nitrogen atmosphere using thermogravimetric analysis (TGA). The results show that the dispersion of amino-functionalized MWNTs (f-MWNTs) in PA6 is more homogeneous than purified MWNTs (p-MWNTs). The presence of MWNTs improves the thermal stability of PA6 under air obviously, but has little effect on the thermal degradation behavior of PA6 under nitrogen atmosphere. The activation energies for degradation under air, E_a, estimated by Kissinger method, are 153, 165 and 169 kJ/mol for neat PA6, p-MWNTs/PA6 and f-MWNTs/PA6 composites, respectively. The p-MWNTs/PA6 composites show two-step degradation not only under air but also under nitrogen atmosphere, however, neat PA6 and the f-MWNTs/PA6 composites exhibit two-step degradation only under air.     

多壁碳纳米管/玻璃纤维/含邻苯二甲腈的苯并噁嗪树脂复合材料的电学与力学性质(英文)

采用溶液共混法及层压成型的方法制备了多壁碳纳米管/玻璃纤维/含双邻苯二甲腈的苯并噁嗪树脂复合材料,并考察了该纳米复合材料的力学及电学性质。材料的渗滤阀值为碳纳米管含量为0.7%,此时,材料也表现出最好的机械性能。通过扫描电镜对材料的断面进行了考察,发现在碳纳米管含量为0.7%时形成了网状结构,因此此时复合材料表现出最好的电学及力学性质。复合材料在碳纳米管含量低于7%时具有很低的吸水性。     

镍铁氧体/碳纳米管复合材料的制备及其对染料废水的吸附性能

用浸渍法制备了镍铁氧体/碳纳米管(NF/MWNTs)复合材料。用XRD、SEM、TEM、VSM、UV-Vis等表征了样品的组成、结构、形貌、磁性能和吸附性能。结果表明,制备的NF/MWNTs复合材料保留了碳纳米管优良的吸附性能,且具有良好的镍铁氧体负载率和优异的磁性能。质量比(mNF/mMWNTs)为1的NF/MWNTs复合材料对亚甲基蓝溶液的最大吸附容量为18.87 mg·g-1,其吸附行为符合Langmuir和Freundlich模型。NF/MWNTs复合材料对亚甲基蓝溶液的脱色率与溶液温度和pH值呈正相关性。此外,NF/MWNTs复合材料回收容易,活化处理简便,可重复使用。     

镍铁氧体/碳纳米管复合材料的制备及其对染料废水的吸附性能

用浸渍法制备了镍铁氧体/碳纳米管(NF/MWNTs)复合材料。用XRD、SEM、TEM、VSM、UV-Vis等表征了样品的组成、结构、形貌、磁性能和吸附性能。结果表明,制备的NF/MWNTs复合材料保留了碳纳米管优良的吸附性能,且具有良好的镍铁氧体负载率和优异的磁性能。质量比(mNF/mMWNTs)为1的NF/MWNTs复合物对亚甲基蓝溶液的最大吸附容量为18.87mg·g^-1,其吸附行为符合Langmuir和Freundlich模型。NF/MWNTs复合材料对亚甲基蓝溶液的脱色率与溶液温度和pH值呈正相关性。此外,NF/MWNTs复合材料回收容易,活化处理简便,可重复使用。     

Nanomechanical properties of silica-coated multiwall carbon nanotubes-poly(methyl methacrylate) composites

The mechanical properties of polymer composites, reinforced with silica-coated multiwall carbon nanotubes (MWNTs), have been studied using the nanoindentation technique. The hardness and the Young's modulus have been found to increase strongly with the increasing content of these nanotubes in the polymer matrix. Similar experiments conducted on thin films containing MWNTs, but without a silica shell, revealed that the presence of these nanotubes does not affect the nanomechanical properties of the composites. While carbon nanotubes (CNTs) have a very high tensile strength due to the nanotube stiffness, composites fabricated with CNTs may exhibit inferior toughness. The silica shell on the surface of a nanotube enhances its stiffness and rigidity. Our composites, at 4 wt % of the silica-coated MWNTs, display a maximum hardness of 120 +/- 20 MPa, and a Young's modulus of 9 +/- 1 GPa. These are respectively 2 and 3 times higher than those for the polymeric matrix. Here, we describe a method for the silica coating of MWNTs. This is a simple and efficient technique, adaptable to large-scale production, and might lead to new advanced polymer based materials, with very high axial and bending strength.     

单斜与锐钛矿双晶相TiO2/MWNTs复合材料的制备及其可见光光催化活性

以超强耐酸碱的表面活性剂-丁基封端脂肪醇聚氧乙烯醚作为晶型调节剂,利用钛酸丁酯和氢氧化钠的水热反应制备了单斜相与锐钛矿相双晶相TiO₂/多壁碳纳米管(简称MWNTs)复合材料,并考察了复合材料的可见光光催化活性。结果显示:MWNTs的加入可调控TiO₂的晶相组成,增强TiO₂的光催化活性,其中含5%MWNTs的样品具有较高的催化降解效率;随煅烧温度的升高,样品的光催化活性大幅提升。其机理归因于(1)促进单斜相和锐钛矿相双晶相结构的形成;(2)碳纳米管优良的导电作用及碳纳米管/TiO₂间的异质结效应;(3)高温下碳纳米管分解产生的碳元素掺杂作用。     

单斜与锐钛矿双晶相TiO2/MWNTs复合材料的制备及其可见光光催化活性

以超强耐酸碱的表面活性剂-丁基封端脂肪醇聚氧乙烯醚作为晶型调节剂,利用钛酸丁酯和氢氧化钠的水热反应制备了单斜相与锐钛矿相双晶相TiO2/多壁碳纳米管(简称MWNTs)复合材料,并考察了复合材料的可见光光催化活性。结果显示:MWNTs的加入可调控TiO2的晶相组成,增强TiO2的光催化活性,其中含5%MWNTs的样品具有较高的催化降解效率;随煅烧温度的升高,样品的光催化活性大幅提升。其机理归因于(1)促进单斜相和锐钛矿相双晶相结构的形成;(2)碳纳米管优良的导电作用及碳纳米管/TiO2间的异质结效应;(3)高温下碳纳米管分解产生的碳元素掺杂作用。     

钾掺杂多壁纳米碳管储氢性能研究

使用自制的钴催化裂解碳氢气法制备多壁纳米碳管,并对其进行退火、掺杂等一系列预处理,然后使用高压高纯氢源,在中压(12 MPa)和室温条件下,进行钾掺杂多壁纳米碳管的储氢性能实验.结果表明:预处理对纳米碳管的储氢性能有很大影响.实验条件下,经过氮气退火,并在1.0 mol/L硝酸钾溶液中掺杂的多壁纳米碳管吸氢量最大(H/C质量分数为3.2%).上述样品在室温下的放氢量一般不超过其吸氢量的50.8%.     

Effects of MWNTs on phase change enthalpy and thermal conductivity of a solid-liquid organic PCM

The effects of multi-walled carbon nanotubes (MWNTs) on the phase change enthalpy (ΔH) and the thermal conductivity (κ) of a solid-liquid phase change materials (PCM), palmitic acid (PA), have been investigated. The results showed that both the ΔH and the κ of the composite were lower than that of PA when the loading of MWNTs was small. As the concentration of MWNTs in the composites increased, the ΔH of the composites was slightly improved and then decreased linearly. However, the κ of the composites was monotonously increased from the minimum value. When the loading of MWNTs increased to 5% and no surfactant was added, the κ of the composite was enhanced to be 26% higher than that of PA. The κ of the composite could be enhanced by CTAB instead of SDBS when the loading of MWNTs was small, as SDBS showed no obvious effect on the κ of the composites. Furthermore, the effects of surface modification of MWNTs on the ΔH and the κ of the composites have also been investigated.     

Effect of interaction between poly(ethylene terephthalate) and carbon nanotubes on the morphology and properties of their nanocomposites

Poly(ethylene terephthalate) (PET) nanocomposites were prepared by melt‐extruding mixtures of PET and functionalized multiwalled carbon nanotubes (MWNTs) with some interaction with PET molecules. For the functionalization of MWNTs, benzyl isocyanate and phenyl isocyanate with different molecular flexibility were employed on the surface of the MWNTs via chemical modification, respectively. The reaction for functionalization of MWNTs was confirmed by FTIR and transmission electron microscopy (TEM) measurements. TEM observations indicated that both benzyl and phenyl isocyanate groups covered the surface of the MWNTs after functionalization. The PET nanocomposites containing isocyanate groups showed improved mechanical properties, including the tensile strength and tensile modulus, compared with those with pristine and acid‐treated nanotubes. These improvements were ascribed to π–π interactions between the aromatic rings of PET molecules and the isocyanate group in MWNTs. The functionalized MWNTs showed a better dispersion of carbon nanotubes in the matrix polymer and a different fractured cross‐section morphology in scanning electron microscope measurements relative to the pristine MWNTs. The crystallinity of the functionalized MWNT‐PET nanocomposites was significantly higher than that of the pristine and acid‐treated MWNTs. FTIR results indicated that the presence of carbon nanotubes induced trans‐conformation of PET chains, and trans conformation was particularly dominant in PET composites incorporating MWNT‐phenyl. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 900–910, 2008     

氢键型碳纳米管增强自修复复合材料的制备和表征

使用低聚酸、二乙烯三胺以及尿素为原料,碳纳米管为增强剂,制备出兼具良好力学性能和室温(30 ℃)自修复性能的氢键型自修复复合材料,同时对材料通过氢键进行自修复的机制进行了合理推测。 首先,对不同碳纳米管添加量的自修复材料进行应力-应变性能测试。 结果发现,随着碳纳米管的添加,材料的应力、应变均有所提高,添加质量分数9%碳纳米管时,材料的应力达到4.1 MPa、应变达到6%以上。 对添加质量分数9%碳纳米管的自修复材料进行表面形态、自修复性能以及热稳定性能测试。 结果表明,碳纳米管与材料有良好的相容性,材料的表面与切面形态相似;在室温下自修复24 h,自修复效率达到100%;10次断裂-修复循环中自修复效率仍能保持90%以上;材料具有良好的热稳定性,最大失重速率下的温度为474.3 ℃。 为下一代类皮肤传感器以及可穿戴智能设备提供了一种选择,为未来该类型自修复聚合物复合材料在高拉伸强度领域的应用奠定了技术基础。     

多壁碳纳米管/聚乙烯复合材料的制备及其导电行为

多壁碳纳米管/聚乙烯复合材料的制备及其导电行为;碳纳米管;高密度聚乙烯;渗流阈值;导电行为;V-PTC特性     

Development of core‐shell structure aided by SiC‐coated MWNT in ABS/LCP blend

Agglomeration is an issue of major concern for unmodified multi‐walled carbon nanotubes (MWNTs)‐aided polymeric composites. To overcome the above‐mentioned problem, multi‐walled carbon nanotubes (MWNTs) are modified by polycarbosilane (PCS)‐derived Silicone carbide (SiC). Acrylonitrile Butadiene Styrene (ABS)/Liquid Crystalline polymer (LCP)/MWCNT nanocomposites are prepared through melt blending in a twin screw extruder. X‐Ray Diffraction (XRD) studies authenticate the creation of ß‐SiC particles. Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) studies reveal the formation of core–shell morphology involving MWNT as the core and SiC‐coated MWNT as the shell. The degree of dispersion of MWNT is far better when it has been coated with SiC. As viewed from Thermo‐gravimetric analysis (TGA), the thermal stability is substantially increased in SiC‐aided nanocomposite in comparison to ABS/LCP/unmodified CNT blend. Glass transition temperature as well as mechanical properties are improved significantly (in the presence of SiC‐coated MWNT) as a result of homogeneous dispersion exhibited by MWNT. Copyright © 2009 John Wiley & Sons, Ltd.     

Comparison of PVDF/MWNT,PMMA/MWNT,and PVDF/PMMA/MWNT nanocomposites: MWNT dispersibility and thermal and rheological properties

Pristine multi-walled carbon nanotubes (MWNTs) were incorporated into poly(vinylidene fluoride) (PVDF), poly(methyl methacrylate) (PMMA), and PVDF/PMMA blends to achieve binary and ternary nanocomposites. MWNTs were more compatible with the PVDF matrix than with the PMMA-containing matrices. MWNT addition did not alter the development of α-form PVDF crystals in the binary/ternary composites. Nucleation and overall isothermal crystallization of PVDF were enhanced by the presence of MWNTs, and enhancements were optimal in the PVDF/MWNT binary composites. Avrami analysis revealed that addition of MWNTs led to more extensive athermal-type nucleation of PVDF, and that PMMA slightly decreased the crystal growth dimension of PVDF. The equilibrium melting temperature (T_m°) of PVDF increased in the binary composites but remained nearly constant in the ternary system. Thermal stability was enhanced in the binary/ternary composites, and enhancements were more evident in the air environment than in nitrogen. Rheological property measurements revealed that the intensely entangled chains of high-molecular weight PVDF dominated the rheological response of PVDF-included samples in the melt state. A (pseudo)network structure was developed in each of the PVDF-included samples as well as in the 1 phr MWNT-added PMMA/MWNT composite. The storage moduli of the PVDF, PMMA, and PVDF/PMMA:1/1 blend increased to 37%, 22% and 34%, respectively, at 40 °C after addition of 1 phr MWNT.     

Use of dynamic rheological behavior to estimate the dispersion of carbon nanotubes in carbon nanotube/polymer composites

Well-dispersed multiwalled carbon nanotube (MWNT)/polystyrene composites have been prepared. Transmission and scanning electron microscopy were employed to observe the distribution of the MWNTs in the composites in a microscopic scale, indicating a nanotube network formed in the matrix. The dispersion of the nanotubes in the polymer was monitored by oscillatory rheology. It was found that the addition of MWNTs in the polymer had a drastic influence on the rheological behavior of the composites. As the MWNT loading increased, Newtonian behavior disappeared at low frequency, suggesting a transition from liquid-like to solid-like viscoelastic behavior. A more homogeneous dispersion or a greater loading of the nanotubes in the matrix produced stronger solid-like and nonterminal behavior, and the composites exhibited less temperature dependence at elevated temperature, compared to the matrix melt.