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。     

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.     

Synergetic effect of fly ash cenospheres and multi-walled carbon nanotubes on mechanical and tribological properties of epoxy resin coatings

The multiform wear of friction pair components is the main cause of marine equipment failure and epoxy resin (EP) coatings have been widely used in this field. Fly ash cenospheres (FACs) and multi-walled carbon nanotubes (MWCNTs) were used to reinforce the tribological properties of EP coatings. The synergetic effects of FACs and MWCNTs on the mechanical and tribological properties of EP coatings were studied. Experimental results show that the tensile and flexural properties of FACs-MWCNTs/EP composites are significantly reinforced. The tribological performance of EP composite coatings under seawater conditions is improved by the synergetic effect of FACs and MWCNTs, especially, the 10 wt.% FACs-1 wt.% MWCNTs/EP coatings behave the most excellent tribological properties. It indicates that FACs can increase the hardness of EP coatings and provide a smoother surface for the water film formation, which decreases the friction coefficient and wear volume. MWCNTs can increase the elasticity modulus of EP, and act as a rope to prevent EP matrix and FACs from being desquamated.     

Effect of hyperbranched epoxy resin on mechanical properties of short carbon fiber‐reinforced epoxy composites

Short carbon fiber‐reinforced composites (SCFRCs) have attracted increasing attention owing to their comprehensive performance and easy processing route. However, the imperfect interfacial adhesion and serious stress concentration at the fiber/matrix interface have hampered their engineering application. In this article, we first report the preparation of SCFRC modified by a low‐viscosity liquid hyperbranched epoxy resin (Hyper E102). We then investigated the effect of Hyper E102 content on thermal and mechanical properties. The results show that the overall performance of the SCFRC first increases and then decreases with the increasing content of Hyper E102. With the incorporation of 12 phr Hyper E102, the tensile strength, fracture toughness, notched, and unnotched impact strength of SCFRC were increased by 16.7, 74.9, 95.3, and 194.5%, respectively. The toughening and reinforcing mechanisms were attributed to the following three aspects. First, the Hyper E102 improves the impregnation property of epoxy matrix against fibers, which helps form a better interfacial adhesion. Second, the incorporation of Hyper E102 reduces the internal stress level and stress concentration of the SCFRC. Finally, the critical crack length inside the SCFRC can be remarkably increased with the incorporation of Hyper E102, which can enhance the damage tolerance of a composite. POLYM. COMPOS., 37:2727–2733, 2016. © 2015 Society of Plastics Engineers     

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.     

Reinforcement of epoxy resins with multi-walled carbon nanotubes for enhancing cryogenic mechanical properties

Epoxy resins are widely applied in cryogenic engineering and their cryogenic mechanical properties as important parameters have to be improved to meet the high requirements by cryogenic engineering applications. Carbon nanotubes (CNTs) are regarded as exceptional reinforcements for polymers. However, poor carbon nanotube (CNT)–polymer interfacial bonding leads to the unexpected low reinforcing efficiency. This paper presents a study on the cryogenic mechanical properties of multi-walled carbon nanotube reinforced epoxy nanocomposites, which are prepared by adding multi-walled carbon nanotubes (MWCNTs) to diglycidyl ether of bisphenol-F epoxy via the ultrasonic technique. When the temperature decreases from room temperature to liquid nitrogen temperature (77 K), a strong CNT–epoxy interfacial bonding is observed due to the thermal contraction of epoxy matrix because of the big differences in thermal expansion coefficients of epoxy and MWCNTs, resulting in a higher reinforcing efficiency. Moreover, synthetic sequence leads to selective dispersion of MWCNTs in the brittle primary phase but not in the soft second phase in the two phase epoxy matrix. Consequently, the cryogenic tensile strength, Young's modulus, failure strain and impact strength at 77 K are all enhanced by the addition of MWCNTs at appropriate contents. The results suggest that CNTs are promising reinforcements for enhancing the cryogenic mechanical properties of epoxy resins that have potential applications in cryogenic engineering areas.     

Influence of carbon nanotube dispersion on the mechanical properties of phenolic resin composites

Despite the much touted mechanical properties of carbon nanotubes, composites reinforced with nanotubes have failed to achieve mechanical properties which rival those present in conventional fiber reinforced polymer composites. This article describes an attempt to bridge this gap. Multi‐walled carbon nanotubes (MWCNT) were synthesized using a chemical vapor deposition method and were dispersed in phenolic resin by both the wet and dry dispersion techniques before molding into composite bars (50 × 5 × 3 mm³). Although no improvement in the mechanical properties of the MWCNT/phenolic composites was observed over the neat resin value when wet mixing dispersion was employed, an improvement of nearly 158% (160 MPa as compared with 62 MPa for neat resin) was achieved in 5 vol% MWCNT containing phenolic resin prepared by the dry mixing. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Surface functionalized carbon nanotubes and its effects on the mechanical properties of epoxy based composites at cryogenic temperature

Epoxies have a wide range of applications in fuel tank fabrication, aerospace, electrical, electronic, and automobile industries. However, these resins are quite brittle, showing poor mechanical performance, especially at cryogenic temperature. The properties of functionalized multi-walled carbon nanotube (MWCNTs)-reinforced epoxy composites were investigated to develop advanced composites for cryogenic use. Two methods were adopted to modify MWCNTs. MWCNTs were first treated by acid mixture, and then maleic anhydride (MA) and isophorone diisocyanate (IPDI) grafting was carried out. At last, the functionalized MWCNTs were integrated into epoxy to prepare MWCNT-reinforced epoxy composites. Raman and XPS analysis proved the effectiveness of acid mixture treatment and confirmed the grafting reaction of MA and IPDI with MWCNTs. TEM analysis indicated that MA and IPDI had been grafted onto the surface of MWCNTs and formed a thin layer. The tensile strength, Young’s modulus, and impact strength of composites at liquid nitrogen temperature (77 K) are all enhanced by the addition of MWCNTs. Results of dynamic mechanical analysis indicated that introducing a small amount of functionalized MWCNTs to epoxy can enhance their storage modulus at 77 K and glass-transition temperature of composites. The results indicated that surface modified MWCNTs can be effectively utilized to enhance the properties of epoxy-based composites at cryogenic temperature.     

Amino-functionalized carbon nanotubes for effectively improving the mechanical properties of pre-impregnated epoxy resin/carbon fiber

Pre-impregnated carbon fiber/epoxy resin (CF/epoxy prepreg) gained its popularity for significant stress applications, especially in the aerospace industry, owing to its excellent resistance and low specific mass. However, these CF/epoxy prepregs have a tendency to crack propagation. A solution for the prepregs fragility is the addition of carbon nanotubes (CNTs), especially those functionalized with amino groups, reinforcing the material due to its exceptional mechanical properties. In this work, the influence of the carbon chain length of two different amino-functionalized CNTs from diverse backgrounds (commercial and laboratory growth CNTs) is studied. The nanofillers were added in CF/epoxy prepregs by dry spraying without solvent aid. CNTs' samples were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis (TGA), while the composites were analyzed by TGA, dynamic-mechanical analysis, and field emission scanning electron microscopy. The various surface treatment occurred at different levels according to the CNTs background, and all samples exhibited a distinct behavior. These differences were also observed in the composites' thermomechanical performance: CNTs functionalized with larger carbon chain amine presented the best results, with an increase of almost 100% in the storage moduli (E'), confirming the efficiency of amino-functionalized CNTs in the reinforcement of CF/epoxy prepregs.     

Effects of novolac resin modification on mechanical properties of carbon fiber/epoxy composites

The epoxy resin matrix of carbon fiber (CF)‐reinforced epoxy composites was modified with novolac resin (NR) to improve the matrix‐dominated mechanical properties of composites. Flexural strength, interlaminar shear strength (ILSS), and impact strength were measured with unfilled, 7 wt% NR, 13 wt% NR, and 18 wt% NR filled to epoxy to identify the effect of adding NR on the mechanical properties of composites. The results showed that both interfacial and impact properties of composites were improved except for flexural property. The largest improvement in ILSS and impact strength were obtained with 13 wt% loading of NR. ILSS and impact strength were improved by 7.3% and 38.6%, respectively, compared with the composite without NR. The fracture and surface morphologies of the composite specimens were characterized by scanning electron microscopy. Intimate bonding of the fibers and the matrix was evident with the content of 7–13 wt% NR range. Decrease of crosslinking density and formation of NR transition layer were deduced with adding NR. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

多壁碳纳米管/环氧树脂复合材料的制备及性能研究

采用浇铸法制备了不同含量多壁碳纳米管(MWCNT)的MWCNT/环氧树脂(EP)复合材料。用扫描电镜观察了MWCNT/EP复合材料的微观结构,发现MWCNT均匀分散在EP中。研究了MWCNT/EP复合材料的导电逾渗行为,材料的逾渗值为0.033%。分析了复合材料的动态力学性能,结果表明MWCNT的加入提高了EP的固化交联程度和韧性,同时复合材料的玻璃化转变温度也有提高。     

多壁碳纳米管改性水泥基复合材料的性能研究

通过试验研究了多壁碳纳米管(MWCNTs)掺量对水泥净浆的力学性能、水化特性、凝结时间、孔隙分布等性能的影响,并采用SEM(扫描电镜)观察与分析了MWCNTs改性水泥净浆的微观形貌。结果表明,MWCNTs的掺入会降低水化过程中矿物的溶解速率,因而延缓了水泥的水化进程;在适宜的掺量范围内,MWCNTs能够有效提升水泥净浆的力学强度,但当其掺量过高时,反而会对力学强度造成不利影响;MWCNTs在水泥净浆中能够分散均匀并降低水泥净浆的孔隙率,使其变得更加密实。     

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.     

Functional interphases with multi-walled carbon nanotubes in glass fibre/epoxy composites

The interphase between reinforcing fibre and matrix is a controlling element in composite performance. We deposited multi-walled carbon nanotubes (MWCNTs) onto electrically insulating glass fibre surfaces leading to the formation of semiconductive MWCNT-glass fibres and in turn multifunctional fibre/polymer interphases. The deposition process of MWCNTs onto glass fibre surfaces involved both electrophoretic deposition (EPD) and conventional dip coating methods. The EPD coating method produces a more homogeneous and continuous nanotube distribution on the glass fibre surface compared with the dip coating. According to fragmentation test results, the interphase with a small number of heterogeneous MWCNTs in the EPD fibre/epoxy composites, mimicking a biological bone structure, can remarkably improve the interfacial shear strength. We found that the semiconductive interphase results in a high sensitivity of the electrical resistance to the tensile strain of single glass fibre model composites. This material provides a possible in situ mechanical load sensor and early warning of fibre composite damage.     

多壁碳纳米管改性水泥基复合材料的性能研究

通过试验研究了多壁碳纳米管(MWCNTs)掺量对水泥净浆的力学性能、水化特性、凝结时间、孔隙分布等性能的影响,并采用SEM(扫描电镜)观察与分析了MWCNTs改性水泥净浆的微观形貌。结果表明,MWCNTs的掺入会降低水化过程中矿物的溶解速率,因而延缓了水泥的水化进程;在适宜的掺量范围内,MWCNTs能够有效提升水泥净浆的力学强度,但当其掺量过高时,反而会对力学强度造成不利影响;MWCNTs在水泥净浆中能够分散均匀并降低水泥净浆的孔隙率,使其变得更加密实。     

Dopamine modification of multiwalled carbon nanotubes and its influences on the thermal,mechanical, and tribological properties of epoxy resin composites

A functionalization process with dopamine on multiwalled carbon nanotubes (MWNTs) has been carried out in order to enhance the tribological properties of MWNTs/epoxy resin (EP) composites. Dopamine modification is of signality for the performance of MWNTs/EP composites. The hardness and flexural strength of the composites were significantly improved with the incorporation of dopamine modified MWNTs, owning to the enhanced interfacial bonding between MWNTs and EP. Meanwhile, the thermal characterizations indicated that dopamine played an important role in improving the thermal stability of MWNTs/EP composites. More importantly, the friction and wear properties of dopamine modified MWNTs/EP composites were enhanced considerably and its wear rate was 85.8% lower than that of pure EP. Dopamine modified MWNTs were linked with the matrix by strong covalent bond to form a great network structure and impeded the movement of polymer molecule chains in the composites. Then the friction load transmitted efficiently through the network structure and the plastic deformation was restrained as well as the initiation and growth of cracks on the worn surfaces. POLYM. COMPOS., 38:116–125, 2017. © 2015 Society of Plastics Engineers     

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...     

Structure and properties of aeronautical composites using carbon nanotubes/epoxy dispersion as nanocomposite matrix

The structure and properties of hybrid multiscale composites containing carbon nanotubes (CNTs) was reported. CNTs were dispersed in epoxy by using high energy ultrasonication, followed by the fabrication of CNT hybrid composites via resin transfer molding (RTM) processing. The processability of CNTs/epoxy systems was explored by a capillary experiment. The dependences of mechanical and electrical properties of the hybrid composites on CNT content were investigated. Microscopic observation confirms the formation of CNTs percolation network. The different roles of CNT networks in mechanical reinforcement and electrical amelioration were analyzed. One explanation based on the dispersion and distribution of CNTs is proposed. It is found that the variations of the hybrid composites with respect to mechanical and electrical properties are attributed to the hierarchical structure in the hybrid composites. As far as the hybrid multiscale composites produced via RTM process is concerned, the formation of CNT percolation network, subjected to dynamic impregnation, is hindered by the presence of continuous fibrous reinforcement. The hierarchical structure influenced by several competing factors reveals great potential in being able to tailor the structural and functional performance of the CNT hybrid composites. The effects of CNTs on the dimensional stability of polymer based composites are also assessed. POLYM. COMPOS., 34:1690–1697, 2013. © 2013 Society of Plastics Engineers     

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.