碳纳米管／PA6纳米复合材料的制备及力学性能

采用RAFT活性聚合反应在碳纳米管表面接枝聚甲基丙烯酸甲酯(二硫代酯化合物作RAFT试剂),并制备了碳纳米管/PA6纳米复合材料。利用FT-IR、TEM、SEM、TGA等测试方法表征接枝聚合物后的碳纳米管,考察了碳纳米管的用量对碳纳米管/PA6纳米复合材料力学性能的影响,并观察了碳纳米管/PA6纳米复合材料冲击断面形貌。结果表明,聚合物接枝到了碳纳米管表面,碳纳米管/PA6纳米复合材料的力学性能明显提高。     

碳纳米管/PVC复合材料的制备及表征

采用RAFT活性聚合方法在碳纳米管表面接枝上聚合物链。然后与PVC通过熔融共混方法复合制备了碳纳米管/PVC纳米复合材料。对复合材料的结构与拉伸强度进行了表征研究,表明接枝聚合物链的碳纳米管显著提高了PVC的拉伸强度。     

碳纳米管／聚氨酯纳米复合材料的制备及性能

采用可逆加成-断裂链转移(RAFT)聚合方法在碳纳米管表面接枝聚甲基丙烯酸甲酯和聚苯乙烯嵌段共聚物MWNT-P(MMA-b-St),对碳纳米管进行改性。采用直接共混法制备碳纳米管/水性聚氨酯纳米复合材料。通过红外光谱(FT-IR)和透射电镜(TEM)对嵌段共聚物的结构进行了表征。碳纳米管加入对乳液成膜性影响不大。热失重分析(TGA)和力学性能测试结果表明,当改性后的碳纳米管含量为聚氨酯固体份的0.75%时,复合材料的热稳定性、拉伸强度和断裂伸长率均较聚氨酯有所提高。     

ATRP方法可控合成碳纳米管/PMMA纳米复合材料

通过多壁碳纳米管的表面改性合成了ATRP引发剂,利用合成的ATRP引发剂进行ATRP活性聚合,成功地在碳纳米管表面接枝聚合物PMMA。利用红外(IR)、透射电镜(TEM)、热重(TGA)以及核磁共振(NMR)表征接枝的碳纳米管,考察了碳纳米管用量对碳纳米管/PMMA纳米复合材料力学性能的影响,结果表明,碳纳米管表面成功接枝聚合物PMMA,PMMA的力学性能得到很大改善。     

碳纳米管对PP/SPTW复合材料力学性能的影响

目的研究不同含量的多壁碳纳米管(CNT)对聚丙烯/六钛酸钾晶须复合材料力学性能的影响。方法将经表面改性处理的多壁碳纳米管与改性过的六钛酸钾晶须、聚丙烯(PP)、马来酸酐接枝聚丙烯(PP-g-MAH),采用熔融共混法,利用双辊开炼机熔融共混制得PP/PP-g-MAH/SPTW/碳纳米管复合材料。比较不同含量的改性多壁碳纳米管对PP/PP-g-MAH/SPTW复合材料力学性能的影响。结果多壁碳纳米管表面经过混酸处理后,在复合材料中分散均匀,与聚合物基体界面间结合良好,对复合材料起到增韧增强作用,但是当碳纳米管质量分数较大时,开始出现团聚现象,反而使复合材料的力学性能降低。结论当碳纳米的质量分数为0.5%左右时,复合材料力学性能最佳。     

表面接枝TDI碳纳米管/聚氨酯复合材料的研制

为改善碳纳米管的分散性,用2,4-甲苯二异氰酸酯(TDI)对碳纳米管进行表面修饰,采用溶液复合方法与聚氨酯共混制备了碳纳米管/聚氨酯复合材料.通过FTIR证明了TDI确实接枝到碳纳米管表面,采用SEM、DMA、TGA等手段分析了碳纳米管修饰后的分散性及复合材料的力学性能和热性能.结果表明,经TDI修饰后的碳纳米管可以更好的分散在聚氨酯基体中,提高了聚氨酯的力学性能和热性能.     

活性可控聚合制备水溶性单壁碳纳米管

利用一种活性可控聚合方法--可逆加成断裂链转移(RAFT)聚合将水溶性聚合物以共价键接枝到单壁碳纳米管的表面,从而制得一种水溶性的单壁碳纳米管(SWCNT).RAFT聚合采用丙烯酸作为单体,双硫酯(PhCS(S)CH(CH3)Ph)为链移剂.结果表明:聚丙烯酸(PAA)已通过共价键接到单壁碳纳米管表面.经RAFT聚合得到的单壁碳纳米管表面接枝聚丙烯酸(PAA-g-SWCNT)在水中的溶解性得到了显著改善.     

PP/碳纳米管复合材料的结构与性能

采用原子转移自由基(ATRP)活性聚合方法在多壁碳纳米管(MWNT)表面接枝丙烯酸丁酯聚合物(PBA),并以此对聚丙烯(PP)进行改性。红外光谱(FT-IR)及透射电子显微镜(TEM)测试结果表明,采用ATRP法成功地将PBA接枝到多壁碳纳米管(MWNT)表面。采用熔融共混法制备了PP/MWNT复合材料,对其力学性能和耐热性能进行了研究,结果表明,接枝聚合物的碳纳米管提高了复合材料的拉伸强度和冲击强度,提高了PP的耐热性。MWNT-PBA和MWNT-COOH加入PP都能提高材料的性能,而MWNT-PBA比MWNT-COOH的作用更加明显。     

碳纳米管表面的RAFT接枝共聚物

首先在碳纳米管表面接枝上可用做RAFT聚合的链转移剂——二硫代碳酸酯,然后用管壁接枝有二硫代碳酸酯的碳纳米管作为链转移剂引发甲基丙烯酸甲酯(MMA)和苯乙烯(St)进行可控的自由基共聚合反应,从而在碳纳米管的管壁接枝上MMA和St共聚物,通过接枝共聚极大地提高了碳纳米管在有机溶剂中的分散性能。并对接枝共聚物的结构进行了较详细的表征。     

碳纳米管/聚甲醛复合材料的结晶形态与力学性能

在对碳纳米管(CNT)进行表面修饰后,采用活性自由基聚合法(ATRP)在其表面接枝聚甲基丙烯酸甲酯(PMMA)。再将接枝上聚合物的碳纳米管添加到聚甲醛中熔融共混制得碳纳米管/聚甲醛纳米复合材料。通过偏光显微镜观察其结晶形态,并研究了功能化碳纳米管的含量对聚甲醛缺口冲击强度的影响,结果表明,CNT-PMMA的加入使聚甲醛球晶细化,复合材料的缺口冲击强度得到提高。     

Transparent conducting film: Effect of vacuum filtration of carbon nanotube suspended in oleum

Vacuum filtration process to fabricate a transparent conducting carbon nanotube (CNT) film is reported. A CNT mat, which is a fibrous sheet of long multi-walled carbon nanotubes (MWNT), was prepared and dispersed in oleum by solution-sonication. The suspension was then vacuum filtered to obtain a thin MWNT layer with improved dispersion. Sheet resistance of the obtained MWNT layer was increased despite the improved dispersion. SEM micrographs and energy dispersive spectroscopy results indicated that the increase of the sheet resistance could be attributed to degradation and oxidation of the MWNT bundles. Though the chemical approach in this study did not improve the electrical property of the CNT mat, a mechanical approach proposed in our recent work was deemed suitable to enhance optical and electrical properties of the CNT mat.     

MWNT reinforced polyurethane foam: Processing, characterization and modelling of mechanical properties

The mechanical properties of a foam material changes when the foam is reinforced with nanoparticles. In this paper it is investigated how the addition of multi-walled carbon nanotubes (MWNTs) influences the effective properties of polyurethane foam. Both pure and nano-reinforced foams containing different amounts of MWNT are produced and both pristine and functionalized MWNT are used as reinforcement. The MWNT are dispersed in the polyol using high-shear mixing with various mixing times to examine how that influences the properties of the produced foams. SEM is used to characterize the microstructure of the produced foams and these examinations reveals that the foam changes from a completely closed cell material for the pure PU foam to a partly open celled foam when adding MWNT. Compressive tests are performed in order to determine the strength and stiffness of the produced foams and the increase in these properties are very dependent on both the wt.% of MWNT and the mixing time used to disperse them in the polyol. Furthermore, the effective properties of the reinforced foams are determined using the Mori-Tanaka (MT) method and generally the correlation between the experimentally and numerically determined properties improves when the mixing time used increases for a constant wt.% of MWNT.     

Cerium oxide dispersed multi walled carbon nanotubes as cathode material for flexible field emitters

Nanomaterials based electron sources are omnipresent in modern flat panel displays. Multi walled carbon nanotubes (MWNT) are the well studied electron emitter among the carbon materials. Since the surface modification of MWNT with low work function materials would have a positive impact on the field emission property of MWNT, cerium oxide (CeO2) nanoparticles dispersed multi walled carbon nanotubes (CeO2/MWNT) were synthesized by catalytic chemical vapour deposition followed by chemical reduction and its field emission property was investigated. The high-purity MWNT as well as CeO2/MWNT showed crystalline structure conformed by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Further characterisation was done with Raman spectroscopy, UV-Visible absorption spectra and Fourier transform IR spectroscopy (FT-IR). The morphology and structural details of CeO2/MWNT composite was probed by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX). The direct evidence of the formation of CeO2/MWNT composites was given by transmission electron microscopy (TEM). The synthesized sample was coated over a flexible carbon paper using spin coating technique. The experiment was performed under a vacuum of 1 x 10(-6) Torr and Fowler-Nordheim equation was used to analyse the data. The turn-on voltage for the cerium oxide dispersed MWNT was found for a current density of 10 microA/cm2. The emission current density from the CeO2 nanoparticles dispersed MWNT reached 0.2 mA/cm2 at a reasonable bias field of 2.58 V/microm. The results were compared with those of pure MWNT and pure CeO2 nanoparticles with literature values.     

Study on the infrared property of polyaniline/multi-wall carbon nanotube composite

Composites of polyaniline (PANI) and multi-wall carbon nanotube (MWNT) were synthesized by in situ polymerization with different MWNT content. The composites were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The SEM photos indicated that a mass of MWNT was enchased into PANI matrix when the content of MWNT was low. With the MWNT content increases, the surface of MWNT was covered with PANI and formed the core-shell structure. From the FT-IR spectroscopy of the composites, it can be confirmed that there was interaction between PANI and multi-wall carbon nanotube. The composites had better thermal stability than pure PANI. Infrared emission property of the composites was analyzed by an IR-II infrared emissivity instrument and an infrared camera. It was found that infrared emission of the composites was lower than pure PANI in all wavelength range and infrared emissivity value was related to the content of MWNT in the composites.     

Preparation and properties of polyarylene ether nitrites/multi-walled carbon nanotubes composites

Polyarylene ether nitriles (PEN)/multi-walled carbon nanotube (MWNT) composites have been successfully fabricated via PEN solution mixing MWNT and then solution-casting. The cast nanocomposite films were characterized by SEM, thermal properties and mechanical properties. The Young's modulus of PEN/MWNT composites was greatly increased with the increase of MWNT concentration. The crystalline behaviors of nanocomposites increased with the increase of MWNT concentration. Thermogravimetric analysis (TGA) measurement showed that MWNT could stabilize PEN when its weight content was greater than 2.0%, and a high char yield in N₂ could be obtained for PEN/MWNT composite at 600 °C.     

表面官能团化多壁碳纳米管/环氧树脂复合材料的制备及性能

本文首先将多壁碳纳米管(MWNT)进行表面化学修饰,接入羧基、胺基等官能团,采用红外光谱进行了表征.以纯化后的MWNT和表面化学修饰的MWNT作为填料,制备了MWNT /环氧树脂复合材料,研究了MWNT的加入对环氧树脂的力学性能、电学性能、热稳定性和玻璃化转变温度等的影响,并利用场发射电镜观察了胺基化MWNT在环氧树脂基体中的分散情况.     

Effect of imidazolium phosphate and multiwalled carbon nanotubes on thermal stability and flame retardancy of polylactide

A series of composites based on polylactide (PLA), have been prepared by melt-blending with multiwalled carbon nanotubes (MWNT) and Tri(1-hydroxyethyl-3-methylimidazolium chloride) phosphate (IP) functionalized MWNT (MIP). The morphology, thermal stability and burning behavior of the composites were investigated by Field Emission Scanning Electron Microscopy (FESEM), Thermogravimetric Analysis (TGA) and Cone Calorimeter Test (CCT), respectively. Significant improvement in fire retardant performance was observed for the PLA/MIP composite from CCT (reducing both the heat release rate and the total heat release) and TGA (increasing the char residue) compared to PLA/MWNT. SEM and Raman spectroscopy were utilized to explore the surface morphology and chemical structure of the char residues. It revealed that the catalytic charring effect of IP, the physical crosslinking effect of MWNT, and the combined effect of both IP and MWNT (forming continuous and compact char layers) were very efficient in improving the flame retarding properties of PLA/MIP composite.     

PP/碳纳米管复合材料的制备及电性能

采用原子转移自由基(ATRP)活性聚合方法在多壁碳纳米管(MWNT)表面接枝丙烯酸丁酯聚合物(PBA),并以此对聚丙烯(PP)进行改性。红外光谱(FT-IR)及透射电子显微镜(TEM)测试结果表明,采用ATRP法成功地将PBA接枝到多壁碳纳米管(MWNT)表面。对PP/MWNT复合材料电性能研究表明,MWNT-PBA的添加比MWNT-COOH更能降低复合材料的电阻率。MWNT-PBA的加入可使PP从绝缘材料转变为抗静电材料。MWNT-PBA和MWNT-COOH加入PP都能提高材料的电性能,而MWNT-PBA比MWNT-COOH的作用更加明显。     

Mechanical properties of multi-walled carbon nanotube/epoxy composites

Untreated and acid-treated multi-walled carbon nanotubes (MWNT) were used to fabricate MWNT/epoxy composite samples by sonication technique. The effect of MWNT addition and their surface modification on the mechanical properties were investigated. Modified Halpin–Tasi equation was used to evaluate the Young’s modulus and tensile strength of the MWNT/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. There was a good correlation between the experimentally obtained Young’s modulus and tensile strength values and the modified Halpin–Tsai theory. The fracture surfaces of MWNT/epoxy composite samples were analyzed by scanning electron microscope.