多壁碳纳米管／环氧树脂复合材料性能研究

采用物理机械方法与化学方法相结合的手段,制备了多壁碳纳米管（MWNTS）／环氧树脂（Epoxy）复合材料。通过力学拉伸试验测试了MWNTs/Epoxy复合材料拉伸强度和拉伸模量与MWNTS添加量的关系,利用扫描电镜（SEM）分析了MWNTS／Epoxy复合材料的拉伸断面,并用表面电阻测试仪对所制备的碳纳米管复合材料进行了电学性能测试。结果表明：经过化学酸化的方法处理后的MWNTS在复合材料中的分散得到了改善,力学性能也得到了明显的提高,但酸处理后的复合材料的电学性能明显低于未处理的复合材料。     

Toughening epoxy adhesives with multi-walled carbon nanotubes

In this paper, the effect of adding multi-walled carbon nanotubes (MWCNTs) with an outer diameter of less than 8 nm to an epoxy adhesive was studied on the adhesive fracture resistance and damage behaviour. The fracture energies of the neat and toughened adhesives were measured by testing double-cantilever beam specimens. Moreover, a cohesive zone model (CZM) was used to numerically study the effect of MWCNTs on the damage behaviour of the toughened adhesives. The maximum improvement of 58.4% in the adhesive fracture energy was obtained when the adhesive was toughened with 0.3 wt% of MWCNTs. The fracture surfaces were analysed using the scanning electron microscopy (SEM) technique. It was found that the presence of MWCNTs in the toughened adhesives caused rougher fracture surfaces. Moreover, some fracture mechanisms including nanotube pull-out and de-bonding were observed in the fracture surfaces. The numerical analyses showed that the damage process zone length was also influenced by MWCNTs. The longest damage process zone was obtained for the toughened adhesive with 0.3 wt% of MWCNTs.     

The use of an electric field in the preparation of glass fibre/epoxy composites containing carbon nanotubes

This paper focuses on the use of electric field for the alignment of carbon nanotubes in glass fibre reinforced thermosetting composites and the associated infusion processing and property modifications. A satisfactory dispersion leads to high quality infusions with uniform distribution and infiltration of intrafibre microchannels by the nanofiller. Field application causes a reduction of resistivity during the process. The resistivity reduction follows an exponential decay with relaxation times in the 100–300 s range. This process is attributed to preferential aggregation in the field direction, whilst indications of individual nanotube alignment are found. The through thickness conductivity of the composite increases by an order of magnitude with the application of the field reaching a value of 1.4 × 10^?3 S/m for 0.1 wt.% nanotubes. The in plane conductivity remains unaffected. The interlaminar toughness increases slightly but statistically significantly upon the addition of nanotubes. A high field leads to a further increase of strain energy release rate to 520 J/m², which corresponds to a value 20% higher than the control. The effects observed on electrical properties are attributed mainly to preferential network formation in the field direction, whilst improvements in interlaminar toughness are linked to the nanotube alignment.     

Selective localization of multi-walled carbon nanotubes in epoxy/polyetherimide system and properties of the conductive composites

Multi-walled carbon nanotubes (MWCNTs) were introduced into the diglycidyl ether of a bisphenol A/polyetherimide (DGEBA/PEI) system. A co-continuous phase structure could be formed by the reaction-induced phase separation (RIPS). The MWCNTs localized selectively in PEI-rich phase which was predicted by theoretical calculations of the wetting coefficient (ω_a) and then confirmed both by optical microscopy and scanning electron microscopy. The thermomechanical properties of DGEBA/PEI/MWCNTs were studied by dynamic mechanical analysis. As the MWCNTs content increased from 0.5 to 1.0 wt %, storage modulus had a tendency of increasing monotonically from 2491 to 2948 MPa and the values of T_g for epoxy-rich phase were almost unchanged at about 130 °C. Subsequently, the result of electrical and thermal properties measurement for composites indicated that their volume resistivity decreased from 3.29 × 10¹⁵ to 3.86 × 10⁶ at 2.0 wt % MWCNTs and thermal conductivity were improved by 36.1% at the same time. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47911.     

碳纳米管/丙烯酸酯橡胶复合材料的制备及性能研究

采用自制的大分子表面改性剂对多壁碳纳米管(MWNTs)进行表面改性,制备改性MWNTs/丙烯酸酯橡胶(ACM)复合材料,研究改性MWNTs用量对复合材料性能的影响,并与炭黑补强的ACM性能进行对比.结果表明:用MWNTs填充ACM制备的材料,其性能远优于炭黑补强的ACM橡胶的性能;随着改性MWNTs用量的增大,复合材料...     

Titania-doped multi-walled carbon nanotubes epoxy composites: Enhanced dispersion and synergistic effects in multiphase nanocomposites

Multi-walled carbon nanotube-epoxy composites are modified with titania nanoparticles in order to obtain multiphase nanocomposites with an enhanced dispersion of carbon nanotubes. The dispersion is monitored using rheological and electrical conductivity measurements. An increase in dispersion quality can be correlated to an increased storage shear modulus of the uncured suspensions and to a decreased electrical conductivity in the bulk nanocomposite. The newly formed microstructure is revealed using transmission electron and optical microscopies. Due to chemical interactions between both types of nanoparticles an attractive potential is generated leading to a significant rearrangement in the particle network structure. Besides an enhanced dispersion, the hybrid structure leads to synergistic effects in terms of the glass transition of the nanocomposites. Although a decrease of the glass transition temperature (T_g) is observed for the nanocomposites containing only one type of filler, the combination of titania and carbon nanotubes into a hybrid structure reduces the decrease of T_g, thus demonstrating the potential of such hybrid structures as fillers for multi-functional epoxy nanocomposites.     

Non-destructive functionalization of multi-walled carbon nanotubes with naphthalene-containing polymer for high performance Nylon66/multi-walled carbon nanotube composites

A new compatibilizer, poly(vinyl benzyloxy methyl naphthalene)-g-poly(t-butyl methacrylate-co-methacrylic acid), was synthesized for Nylon 66 (N66)/multi-walled carbon nanotube (MWCNT) composites. It has been shown that the naphthalene unit in the main chain of the compatibilizer interacts with MWCNTs by π–π interaction and that the carboxylic acid unit in the graft chain of the compatibilizer interacts with the amide group of N66. The use of the compatibilizer produces well-dispersed MWCNTs in N66 matrix, which results in improved mechanical and electrical properties of the composites, while the simple mixture of N66/MWNCTs without the compatibilizer exhibits poor mechanical and electrical properties due to severe aggregation of MWCNTs. It is also found that the compatibilizer with a small amount of carboxylic acids is more effective for improving the mechanical and electrical properties of N66/MWCNT composites.     

Corrosion protection by epoxy coating containing multi-walled carbon nanotubes

Epoxy coatings that contained multiwalled carbon nanotubes (MWCNTs) were prepared. Further, the effect of the MWCNTs on the hydrophobicity and water transport behavior, and hence, on corrosion resistance provided by the epoxy coating were examined using hygrothermal cyclic tests and electrochemical impedance spectroscopy (EIS). The water transport behavior of epoxy coatings with higher MWCNT content decreased to a larger extent for coatings with higher surface hydrophobicity. The corrosion protection of carbon steel coated with epoxy coating that contained MWCNTs correlated well with water transport behavior and hydrophobicity.     

功能化碳纳米管/环氧树脂多孔复合材料制备及电磁屏蔽性能

以马来酸酐（MA）为功能性单体,通过自由基反应制备了马来酸酐功能化的多壁碳纳米管（MA-MWCNT）;以MA-MWCNT、环氧树脂、蓖麻油酸改性的四乙烯五胺固化剂、釉粉、水为原料,通过悬浮乳液聚合法制备了功能化碳纳米管/环氧树脂多孔复合材料。采用拉曼光谱、X射线衍射、红外光谱、X射线光电子能谱对功能化的碳纳米管进行了表征和测试。采用扫描电镜（SEM）、表面电阻测量仪、矢量网络分析仪对复合材料的表面形貌、电导率和电磁屏蔽性能进行了测试。结果表明：马来酸酐功能化单体的引入能够很好地改善碳纳米管的分散性能及材料的电磁屏蔽性能;随着碳纳米管含量的增多,复合材料的电导率增大,电磁屏蔽效能峰值增大,材料的电磁屏蔽性能增强;加入功能化的碳纳米管比加入未功能化碳纳米管的电磁屏蔽性能高,多孔复合材料比无孔复合材料的电磁屏蔽性能高。当加入功能化的碳纳米管的量为3%时,制备得到的多孔材料电磁屏蔽性能最佳,其电磁屏蔽性能峰值达到31.1dB。     

可溶性碳纳米管与NR或CIIR复合材料性能的研究

通过有机改性制备可溶性碳纳米管（s—CNTs），采用溶液共沉法制备s—CNTs／NR和s—CNTs／CIIR复合材料，并对复合材料的性能进行研究。结果表明，通过有机改性制备的s—CNTs可均匀地分散于有机溶剂中；随s—CNTs用量增大，s-CNTs／NR复合材料邵尔A型硬度和密度增大，拉伸强度和拉断伸长率先增大后减小，s—CNTs／CIIR复合材料邵尔A型硬度和密度均增大，拉伸强度总体呈增大趋势，拉断伸长率变化不大，表面电阻率明显减小。     

Mechanical behavior of phenolic-based composites reinforced with multi-walled carbon nanotubes

Two types of carbon nanotubes (CNTs), the network multi-walled nanotubes (MWNTs) and the dispersed MWNTs, were used for fabricating MWNTs/phenolic composites. The MWNTs were synthesized using the floating catalyst method through the chemical vapor deposition process. The effects of the MWNT content on the mechanical properties of the composites were investigated. Modified Halpin-Tsai equation was proposed to evaluate the Young’s modulus and tensile strength of the MWNTs/phenolic composites by adopting an orientation factor and an exponential shape factor in the equation. It is found that the results obtained from the modified Halpin-Tsai equation on tensile strengths and Young’s moduli fit successfully the experimental ones. The tensile fracture surfaces of MWNTs/phenolic composites were examined using field emission scanning electron microscope to study the failure morphologies of the MWNTs/phenolic composites.     

Noncovalent functionalization of multi-walled carbon nanotubes with pyrene-linked nylon66 for high performance nylon66/multi-walled carbon nanotube composites

A new interfacial agent, 1-pyrenebutyric chloride (PBC), was synthesized for use in nylon 66 (PA66)/multi-walled carbon nanotube (MWCNT) composites. It has been shown that the pyrene units in PBC adsorb onto the MWCNT surface by physisorption, and the acyl chloride units in PBC react with amine end groups in PA66 during melt extrusion. As a result, PBC that was covalently bonded with PA66 formed at the interface between the MWCNT and PA66 matrix. The PA66/MWCNT composite containing PBC exhibited the best interfacial adhesion between MWCNT and PA66 and the highest level of MWCNT dispersion in the PA66 matrix among the composites examined. It was also found that the PA66/MWCNT composite with the higher interfacial adhesion energy between PA66 and MWCNT exhibited a higher level of reinforcement.     

Mechanical and barrier properties of epoxy resin filled with multi-walled carbon nanotubes

Different multi-walled carbon nanotube (MWCNT) concentrations were incorporated in an epoxy resin and both the epoxy precursor and the composite were cured at 110 °C with a tertiary amine. Infrared spectroscopy was used to follow the curing progress by determining the decrease of the band due to the epoxy group. It was shown that the presence of MWCNTs accelerates the process, halving the time for the disappearance of the epoxy band. Atomic force microscopy demonstrated that the carbon nanotubes are well embedded in the epoxy matrix and singularly dispersed or in bundles, depending on their concentration. As a consequence of the good dispersion and interpenetration of the carbon nanotubes in the epoxy matrix, the glass transition temperature increased with increasing MWCNT concentration. Dynamic-mechanical analysis indicated a higher elastic modulus, particularly at high temperatures. The study of the transport properties, sorption and diffusion of water vapour at different activities, showed improved barrier properties on increasing the CNT concentration.     

Effect of dispersion conditions on the mechanical properties of multi-walled carbon nanotubes based epoxy resin composites

A suitable dispersion technique and quantitative evaluation of degree of dispersion of carbon nanotubes (CNT) in any solvent and matrix system has been one of the key issues for achieving enhanced performance of CNT reinforced composites. We report the use of UV–vis spectroscopy as a useful technique to ascertain the degree of dispersion of multiwalled carbon nanotubes (MWCNT) in the epoxy resin. The study has enabled to maximize dispersion of MWCNT in the epoxy resin using two different routes. As a result the composite samples prepared with only 0.3 wt.% amine functionalized MWCNT showed flexural strength of 140 MPa over the neat resin value of 55 MPa, an improvement of ~155% which is maximum reported so far for CNT-epoxy isotropic composites.     

Fabrication of bimetallic nanoparticles/multi-walled carbon nanotubes composites for microelectronic circuits

A method for the fabrication of electrically-conducting polymer composites has been developed by mixing modified multi-walled carbon nanotubes (MWCNTs) functionalized by bimetallic nanoparticles (Ag/Ni/MWCNTs) into a UV curable resin. MWCNTs were treated by a concentrated H₂SO₄/HNO₃ mixture followed by ultrasonication with AgNO₃ and NiSO₄ in an ethylene glycol solution, producing MWCNTs decorated with Ag and Ni nanoparticles. The microstructure and surface morphology of the Ag/Ni/MWCNTs were investigated by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectrometry. It was found that the addition sequences of NiSO₄ and AgNO₃ influence the morphology of the Ag/Ni/MWCNTs. The electrically-conducting polymer composites were obtained by dispersing the prefabricated Ag/Ni/MWCNTs in UV curable resin, the curing process of which was tracked by Fourier transform infrared spectroscopy, and the electrical resistance was measured using the four-probe method. The fabrication of microelectronic patterns made by screen printing on different substrates was described.     

A novel failure analysis of multi-walled carbon nanotubes in epoxy matrix

The failure analysis of reinforcing elements is of great significance to understand the structure-property relationship in polymer composites. Herein, we reported an improved methodology to ascertain and contrast the failure modes from one pair of homologous fracture surfaces of multi-walled carbon nanotubes (MWCNTs)/epoxy samples at high-magnification using scanning electron microscopy. Three possible failure modes of MWCNTs, i.e. pullout, immediate fracture and sliding-fracture, were proposed to account for the fractographic observation. Based on this approach, the failure modes of MWCNTs before and after surface modification were quantitatively discussed.     

Effect of carbon nanotubes on the curing and thermomechanical behavior of epoxy/carbon nanotubes composites

The processing of carbon nanotube based nanocomposites is one of the fastest growing areas in materials research due to the potential of significantly changing material properties even at low carbon nanotube concentrations. The aim of our work is to study the curing and thermomechanical behavior of carbon nanotube/epoxy nanocomposites that are critical from an application standpoint. Multiwall carbon nanotubes–epoxy composites are prepared by solvent evaporation based on a commercially available epoxy system and functionalized multiwalled carbon nanotubes. Three weight ratio configurations are considered (0.1, 0.5, and 1.0 wt%) and compared to both the neat epoxy to investigate the nano‐enrichment effect. We focus here on the modification of the curing behavior of the epoxy polymer in the presence of carbon nanotubes. It has been observed that introducing the multiwall carbon nanotubes delays the polymerization process as revealed by the modification of the activation energy obtained by differential scanning calorimetry. The viscoelastic response of the nanocomposites was studied from the measurements of storage modulus and the loss factor using dynamic mechanical analysis to evaluate the effect of the interface in each matrix/carbon nanotube system with changing matrix mobility. These measurements provide indications about the increase in the storage modulus of the composites, shift in the glass transition temperature due to the restriction of polymer chain movement by carbon nanotubes. POLYM. COMPOS., 35:441–449, 2014. © 2013 Society of Plastics Engineers     

Dielectric properties of epoxy composites with modified multiwalled carbon nanotubes

We report here a high dielectric percolative polymer nanocomposite, fabricated by a combination of triethylene-tetramine (TETA) modified multiwalled carbon nanotube (named as TETA-MWNT) within epoxy resin matrix. In this composite system, with various TETA-MWNT volume fractions, the dielectric constant (K) is well fitted by the scaling law of the percolation theory with the percolation threshold f _c is 0.042 and the critical exponent p is 0.786. At 1,000 Hz of room temperature, the value of the dielectric constant is as high as 421 with the TETA-MWNT content of 4.14vol%, which is almost 60 times higher than that of epoxy resin. In contrast, a simple blend of pristine MWNT in epoxy composite shows evident lower dielectric constant and much higher loss with the same volume fraction.