MWCNTs/PS复合材料导电性能及导电行为研究

多壁碳纳米管(MWCNTs)与聚苯乙烯(PS)熔融共混,制备试样,部分试样进行热处理。通过导电性能的测试研究了不同测试温度对MWCNTs/PS非结晶复合材料电性能及其导电行为的影响;通过SEM观察了该复合材料的表面形貌。研究结果表明:随着MWCNTs加入量的增加,MWCNTs/PS的体积电阻率(ρ)呈现下降趋势;当MWCNTs加入量达到8.0%,复合材料的ρ降到102数量级;120℃热处理后MWCNTs(10.0%)/PS复合材料的ρ比未经热处理的ρ下降近1个数量级;MWCNTs(10.0%)/PS 1-3型复合材料的PTC行为不明显,但5.0%MWCNTs/PS1-3型复合材料的PTC效应明显,在150℃以后,出现NTC效应。     

超临界流体制备PMMA/MWCNTs微孔发泡复合材料及其导电性能

通过溶液-熔融共混法制备聚甲基丙烯酸甲酯(PMMA)/多壁碳纳米管(MWCNTs)复合材料,辅以透射电子显微镜对MWCNTs在PMMA基体中的分散性进行表征,发现MWCNTs分散性良好,直径约为10 nm,平均长度约为200 nm.通过超临界流体发泡工艺对PMMA/MWCNTs复合材料导电网络进行调控,从而获得具有不同...     

改性碳纳米管增强聚乳酸复合材料的制备及其性能

利用十二烷基苯磺酸钠对多壁碳纳米管(MWCNTs)表面改性,得到改性碳纳米管(SMCNTs),通过熔融共混法制备SMCNTs增强左旋聚乳酸(PLLA)导电复合材料,通过形貌观察、电性能测试和结晶行为等对复合材料性能进行研究.结果表明:SMCNTs在PLLA基体内可实现良好分散,没有明显团聚体的形成;PLLA/SMCNT...     

浓乳液模板法制备导电多孔聚氨酯复合材料

通过浓乳液模板法制备了一种孔径可控的多孔聚氨酯弹性材料,并以多壁碳纳米管(MWCNTs)为导电填料制备了压力敏感的导电多孔聚氨酯复合材料。采用扫描电子显微镜分析了乳化剂含量、蓖麻油含量对多孔聚氨酯形貌的影响。结果表明,乳化剂含量越多,聚氨酯孔径越小;蓖麻油含量越多,聚氨酯孔结构越偏离球形,且得到的聚氨酯材料孔径为微米级;将酸化碳纳米管引入到体系中作为导电填料,即得到压力敏感的导电聚氨酯多孔复合材料,随碳纳米管负载含量的增加,复合材料的电阻可降低2个数量级;随着外应力的增加,聚氨酯复合材料的电阻同样可降低2个数量级。     

多壁碳纳米管/硅橡胶复合材料的界面作用

采用超高速剪切法制备了未改性多壁碳纳米管(MWCNTs)/硅橡胶复合材料、羟基化MWCNTs/硅橡胶复合材料和羧基化MWCNTs/硅橡胶复合材料,通过傅里叶变换红外光谱仪、多功能表面分析电子能谱仪和动态力学分析研究了复合材料的界面作用。结果表明,羧基化MWCNTs/硅橡胶复合材料的界面作用最强,羟基化MWCNTs/硅橡胶复合材料其次,未改性MWCNTs/硅橡胶复合材料最弱。     

CB/MWCNTs/PP导电复合材料的制备与性能表征

通过熔融共混、注塑成型将多壁碳纳米管(MWCNTs)母粒、炭黑(CB)母粒与聚丙烯(PP)混合制备CB/MWCNTs/PP导电复合材料。复合材料中导电填料MWCNTs体积分数为1%,通过改变炭黑体积分数,探究CB含量的变化对复合材料导电性能、力学性能和流变性能的影响。导电测试结果表明,当CB体积分数介于3%~5%时,复合材料达到电流逾渗;超声共振结果表明,复合材料的弹性模量会随着CB含量的增大而增大,而泊松比对CB含量的变化并不敏感;DMA结果表明,复合材料玻璃化转变温度(T_g)会随着CB含量的增加而降低,而储能模量和损耗模量在低温区会随着CB的增大而上升;MCR分析结果表明,当CB体积分数介于1%~3%时,复合材料达到流变逾渗,复合黏度对低频率扫描不敏感,随着CB体积分数的增大而增加。随着频率上升,不同含量材料的复合黏度越来越逼近,并且呈现剪切变稀现象。     

EP/AlN/MWCNTs导热复合材料性能研究

采用硅烷偶联剂KH–550对氮化铝(Al N)颗粒进行表面处理,对多壁碳纳米管(MWCNTs)进行氧化处理。通过溶剂和超声分散法,分别制备了环氧树脂(EP)/Al N,EP/MWCNTs及EP/Al N/MWCNTs复合材料,用万能试验机测试了复合材料的冲击强度与弯曲强度,用热导率测定仪测试了其热导率,用扫描电子显微镜和透射电子显微镜测试了其微观结构。结果表明,Al N,MWCNTs在EP基体中分散均匀;单独或同时加入填料Al N和MWCNTs均能够提高EP复合材料的力学性能和导热性能。随着Al N,MWCNTs含量的增加,EP/Al N,EP/MWCNTs及EP/Al N/MWCNTs复合材料的冲击强度和弯曲强度均呈现先增大后减小的趋势,而热导率呈现逐渐增大的趋势;EP/Al N/MWCNTs复合材料的热导率明显高于相同份数Al N的EP/Al N复合材料的热导率。当MWCNTs含量为1.5份、Al N含量为40份时,EP/Al N/MWCNTs复合材料的综合性能最优异,冲击强度为22.118 k J/m2,弯曲强度为124.40 MPa,热导率达到0.434 W/(m·K)。     

碳基聚丙烯导电复合材料的制备及性能研究

采用两步分散方法,即依次通过粉体预混和熔融共混两步法制备了碳基聚丙烯(PP)导电复合材料,利用不同的表征手段研究了碳基材料用量对PP复合材料性能的影响。结果表明:片状膨胀石墨(EG)和纤维状多壁碳纳米管(MWCNTs)在PP体系中形成了完整而稳定的导电网络,而且分散均匀,致使PP的拉伸强度和断裂伸长率明显提高,在EG/MWCNTs=0.1:0.1时,复合材料的拉伸强度和断裂伸长率达到最大。复合碳基材料的加入,影响了PP的结晶行为,改善了PP复合材料的耐热性能,显著提高了PP复合材料的导电性能,其逾渗阈值在EG/MWCNTs为0.1:0.1到0.5:0.5之间。     

壁碳纳米管的表面改性与分散工艺研究

通过浓硝酸对多壁碳纳米管(MWCNTs)进行纯化,以钛酸四丁酯为原料,采用溶胶-凝胶法对纯化后的MWCNTs进行表面改性,采用XRD、TEM分析手段对表面改性的多壁碳纳米管的物相组成和形貌进行表征,并研究了MWCNTs在乙醇中的分散性,结果表明:采用浓硝酸浸泡可以有效地纯化MWCNTs;采用溶胶-凝胶法在MWCNTs表面负载了纳米TiO2;纯化、负载纳米TiO2和超声波震荡提高了MWCNTs在乙醇中的分散性.     

PEEK/MWCNTs复合材料性能研究

采用注塑成型制备了聚醚醚酮(PEEK)/多壁碳纳米管(MWCNTs)复合材料,探讨了MWCNTs的表面官能团和含量对PEEK/MWCNTs复合材料电性能、摩擦性能、力学性能及断面形貌的影响。结果表明,羟基和羧基的引入可显著提高复合材料的性能,改善界面结合情况,且随着MWCNTs含量的增加,复合材料的表面电阻率和磨损量明显降低,力学性能显著提高。MWCNTs-COOH加入后,出现逾渗现象,逾渗值为3%,表面电阻率达1.89×10~6Ω;摩擦系数降低,承载能力提高1倍以上;MWCNTs-COOH质量分数为4%时,磨损量为0.6mg,比纯PEEK降低71.4%,综合性能最优。     

Characterization of the surface energies of functionalized multi-walled carbon nanotubes and their interfacial adhesion energies with various polymers

The surface energies of pristine multi-walled carbon nanotubes (MWCNTs) and MWCNTs functionalized with carboxylic acid (MWCNT-COOH), acyl chloride and ethyl amine were characterized, and the effects of the changes in MWCNT surface energies on the interfacial adhesion and reinforcement of the composites were explored. When the surface energy of pristine MWCNTs was compared to that of functionalized MWCNTs, a decrease in the dispersive surface energy and an increase in the polar surface energy were observed. Interfacial adhesion energies between MWCNTs and various polymers were estimated from surface energy values of MWCNTs and various polymers. Among the MWCNTs, polyethylene, polystyrene and bisphenol-A polycarbonate (PC) had the highest interfacial energy with pristine MWCNTs, while nylon 6,6 and polyacrylamine exhibited the highest interfacial energy with MWCNT-COOH. When tensile properties and adhesion at the interface of PC and nylon 6,6 composites containing MWCNTs were examined, composites having high interfacial adhesion energy exhibited greater adhesion at the interface and reinforcement.     

Functionalization of multi-wall carbon nanotubes to reduce the coefficient of the friction and improve the wear resistance of multi-wall carbon nanotube/epoxy composites

Functionalization of multi-wall carbon nanotubes (MWCNTs) was achieved by grafting carboxyl groups and amino groups. Fourier transform infrared spectroscopy was used to detect the changes produced by functional groups on the surface of the MWCNTs. Three different MWCNTs were incorporated into epoxy resin and the friction and wear behavior of MWCNT/epoxy composites was investigated using a M-2000 wear testing machine at different sliding speeds under different applied loads. Scanning electron microscopy was used to observe the worn surfaces of the samples. The results indicated that the functional groups had been grafted on the surface of MWCNTs. Compared with neat epoxy, the composites with MWCNTs showed a lower friction coefficient and wear rate, and the wear rate decreased with the increase of MWCNT loading. Combining epoxy resin with MWCNTs is an efficient method to improve the wear resistance and decrease the coefficient of friction.     

Synthesis and characterization of functionalized carbon nanotubes with different wetting behaviors and their influence on the wetting properties of carbon nanotubes/polymethylmethacrylate coatings

The synthesis and characterization of hydrophobic functionalized multi-wall carbon nanotubes (MWCNTs) were investigated and their influence on the wetting properties of organic coatings and composites was studied. Functionalization was performed using oxidation, 1,3-dipolar cycloaddition, and silanization. Silanization was conducted using three hydrophobic silane precursors: 1H,1H,2H,2H-perfluorodecyltrimethoxysilane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, and triethoxyoctylsilane. Functionalization was directly confirmed and characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, and scanning electron microscopy. The water contact angle of the functionalized MWCNTs was 40–142° for different surface functionalities and the functionalized MWCNTs were incorporated into an acidic solution of polymethylmethacrylate. The effect of surface functionality and the concentration of the functionalized MWCNTs on the wetting properties of these composites were studied by measuring the water contact angle. Under optimum conditions, composite surfaces with water contact angles greater than 110° were obtained. Atomic force microscopy was used to determine the topography of the surface and energy dispersion spectroscopy was used to determine the distribution of the functionalized MWCNTs in the composite film. It was shown that the hydrophobic functionalized MWCNTs migrated to the surface; this was more pronounced for the more hydrophobic MWCNTs.     

High dispersion ability of fluorene‐based polyester as a polymer matrix for carbon nanotubes

The high compatibility of fluorene‐based polyester (FBP‐HX) as a polymer matrix for multiwalled carbon nanotubes (MWCNTs) is discussed. A low surface resistivity due to the fine dispersion of MWCNTs in FBP‐HX and polycarbonate (PC) is reported. With a solution‐casting method, a percolation threshold with the addition of between 0.5 and 1.0 wt % MWCNTs was observed in the MWCNT/PC and MWCNT/FBP‐HX composites. Because of the coverage of FBP‐HX on the MWCNTs, a higher surface resistivity and a higher percolation ratio of the MWCNT/FBP‐HX composites were achieved compared with the values for the MWCNT/PC composites. In the MWCNT/FBP‐HX composites, MWCNTs covered with FBP‐HX were observed by scanning electronic microscopy. Because of the coverage of FBP‐HX on the MWCNTs, FBP‐HX interfered with the electrical pathway between the MWCNTs. The MWCNTs in FBP‐HX were covered with a 5‐nm layer of FBP‐HX, but the MWCNTs in the MWCNT/PC composites were in their naked state. MWCNT/PC sheets demonstrated the specific Raman absorption of the MWCNTs only with the addition of MWCNTs of 1 wt % or above because of the coverage of the surface of the composite sheet by naked MWCNTs. In contrast, MWCNT/FBP‐HX retained the behavior of the matrix resin until a 3 wt % addition of MWCNTs was reached because of the coverage of MWCNTs by the FBP‐HX resin, induced by its high wettability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of surface modification of carbon nanotube on microstructures and properties of polyamide 66/multiwalled carbon nanotube composites

The melt‐mixing polyamide 66 (PA66) composite samples that incorporated pure, acid‐ and amine‐functionalized multiwalled carbon nanotubes (MWCNTs) were prepared in order to enhance mechanical and frictional properties of PA66 composites. The homogeneous dispersion of amine‐functionalized MWCNTs (D‐MWCNTs) in PA66 matrix was observed from the significantly uniform morphology of tensile fractured surface of the composites. Differential scanning calorimetry measurement indicates that D‐MWCNTs acted as effective nucleation agent for PA66 matrix and the crystallinity of PA66 was increased. The fracture stress and tensile modulus of the composites were significantly improved with the incorporation of D‐MWCNTs, owing to the good dispersion of D‐MWCNTs. Compared with PA66, the PA66 composites with 1.0 wt% D‐MWCNTs were improved considerably in both wear and friction properties owing to the change of the tribological mechanisms. The good dispersion of D‐MWCNTs in PA66 and good interface compatibility between D‐MWCNTs and PA66 favored the formation of a thin layer on the contact surfaces during wear and friction test, which played an important role in reducing wear and friction of the composite and in suppressing the transverse cracks. These results prove the importance of D‐MWCNTs in a positive change of the mechanical and frictional properties of PA66 composites and suggest the applicability prospect of PA66/D‐MWCNTs composites in engineering components.POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Surface modification of multiwalled carbon nanotubes via gliding arc plasma for the reinforcement of polypropylene

To increase the applicability of multiwalled carbon nanotubes (MWCNTs), functional groups were generated on the generally inert surface of MWCNTs using gliding arc (GA) plasma. MWCNTs were modified using plasma polymerization with styrene (St) as monomer. The surface compositional and structural changes that occur on MWCNTs were investigated using FT‐IR, Raman spectroscopy, BET surface area, and elemental analysis. Dispersion of the treated MWCNTs in different solvents was evaluated. Transmission electron microscopy images showed that the plasma‐treated MWCNTs had a better dispersion than the untreated ones in nonpolar solvents. Subsequently, MWCNTs‐reinforced polypropylene (PP) composites were prepared by internal batch mixing with the addition of 1.0 wt % MWCNTs. The morphology of MWCNTs/PP nanocomposites was studied through scanning electron microscopy. Observations of SEM images showed that the plasma‐treated MWCNTs had a better dispersion than the untreated MWCNTs either on the composite fracture surfaces or inside the PP matrix. Moreover, the mechanical tests showed that the tensile strength and elongation at break were improved with the addition of polystyrene‐grafted MWCNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Multi-functional multi-walled carbon nanotube-jute fibres and composites

Jute fibres and corresponding epoxy based composites with sensing abilities could be realized by depositing multi-walled carbon nanotubes (MWCNTs) on the surfaces of jute fibres or fabrics using simple and scalable dip coating. The formation of electrically semiconducting MWCNT networks on jute fibre surfaces was confirmed, which in turn caused the formation of jute/epoxy interphases with highly concentrated MWCNTs. The sensing behaviour of the MWCNT coated jute fibres and jute/epoxy composites for temperature, relative humidity and stress/strain was further established in detail, which were strongly influenced by the intrinsic physical and chemical features of the fibres. In addition, a significant improvement in dielectric properties of the MWCNT-jute/epoxy composites was observed compared to neat jute/epoxy composites. Based on this approach, the electrically insulating natural fibres along with semiconducting MWCNTs on surface will stimulate and realize a broad range of multi-functional applications.     

Increasing the interfacial strength in carbon fiber/epoxy composites by controlling the orientation and length of carbon nanotubes grown on the fibers

Multi-walled carbon nanotubes (MWCNTs) were grafted onto carbon fibers (CFs) using an injection chemical vapor deposition method. The orientation and length (16.6–108.6 μm) of the MWCNTs were controlled by the surface treatment of the CFs and the growth time, respectively. The interface between the MWCNTs and the CFs indicated the grafted CNTs were immobilized by embedding catalyst on CFs. Two orders of magnitude increase in the specific surface areas of CFs was obtained by grafting the MWCNT. MWCNT–CF hybrids exhibited good wettability with the epoxy resin due to the surface roughness and capillary action. Single-fiber composite fragmentation tests revealed an remarkable improvement of interfacial shear strength (IFSS) controlled by the orientation and length of MWCNTs. MWCNTs with an perpendicular alignment and long length showed a high IFSS in epoxy composites due to better wettability and a large contact interface between the hybrids and the resin. Hybrids with an optimum length (47.2 μm) of aligned MWCNTs showed a dramatic improvement of IFSS up to 175% compared to that of pristine CFs.     

Efficient functionalization of multi‐walled carbon nanotubes with p‐aminophenol and their application in the fabrication of poly(amide‐imide)‐matrix composites

The ultrasonically assisted preparation and characterization of poly(amide‐imide) (PAI) composites containing functionalized multi‐walled carbon nanotubes (MWCNTs) are reported. To improve the dispersion in and compatibility with the polymer matrix, the MWCNTs were surface‐modified with p‐aminophenol (p‐AP) under microwave irradiation. The process is fast, one‐pot, easy and results in a high degree of functionalization as well as dispersibility in organic solvents. The p‐AP‐functionalized MWCNTs (MWCNTs‐AP) were analysed by means of field emission and transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction and thermogravimetric analysis (TGA). The results consistently confirm the formation of p‐AP functionalities on MWCNTs which are able to undergo additional reactions, while the structure of the MWCNTs remains relatively intact. MWCNTs‐AP/PAI hybrid films were prepared with various MWCNTs‐AP contents (5–15 wt%) using a solution‐casting technique. Microscopic observations show that the dispersion of the MWCNTs‐AP is improved as a result of the organic groups on the MWCNT surface and functional groups in the PAI structure. The properties of the obtained composites were characterized extensively using the aforementioned techniques. TGA results show that the hybrid films exhibit a good thermal stability. Tensile mechanical testing was performed for the prepared composites, the results of which indicate an increase in the elastic modulus and tensile strength with increasing MWCNTs‐AP content. © 2013 Society of Chemical Industry     

Preparation and characterization of 2‐hydroxyethyl methacrylate–chitosan functionalized multiwall carbon nanotubes nanocomposites

Surface of chitosan (CS) functionalized multiwall carbon nanotubes (MWCNTs) was modified by using 2‐hydroxyethyl methacrylate (HEMA) monomers and the composites were synthesized under microwave irradiation. In this approach, multiwalled carbon nanotubes were functionalized with HEMA and CS in two steps. Firstly, CS was grafted onto the surface and side wall of carbon nanotubes by using microwave irradiation. At the second step, HEMA monomers were grafted onto the polymeric matrix surface. The modified surface of CS functionalized multi‐walled carbon nanotube composites are confirmed by Fourier transform infrared spectroscopy. Moreover, Transmission electron microscopic and scanning electron microscopic images show the morphological changes of the carbon nanotubes. Thermal gravimetric analysis shows content of HEMA–CS functionalized MWCNTs in the composites. Dispersibility of pristine MWCNTs was compared with dispersibility of resultant composites in aqueous phase as well. Results show that composites have higher dispersibility in aqueous phase. Considering the biomedical importance of HEMA monomers and CS polymer, in future, these materials are expected to be useful in the pharmaceutical industry as novel biomaterials composites with potential applications in drug delivery. POLYM. COMPOS., 35:495–500, 2014. © 2013 Society of Plastics Engineers