Carbon Nanotubes In Polymer Matrix Research Articles

Buckling analysis of nanocomposite beams based on refined beam theory by considering the Agglomeration effect of CNTs

The present work deals with buckling load behavior of nanocomposite beams by considering the agglomeration effect of single-walled carbon nanotubes (CNTs) and different patterns CNTs in polymeric matrix. The material properties of nanocomposite beams are estimated using the Eshelby–Mori– Tanaka approach based on an equivalent fiber. The equations of motion are derived based on refined beam strain gradient theory, employing Hamilton’s principle and using Differential Quadrature Finite Element Method (DQFEM) derived from the differential quadrature method (DQM). The results are compared with analytical results in the literature. It is remarked that mechanical properties and therefore critical buckling loads of nanocomposite beam are seriously affected by CNTs agglomeration.

Wireless strain sensing using carbon nanotube composite film

Carbon nanotubes in polymer matrix form a complex network which consists of resistors, inductors, and capacitors. The present research focuses on wireless strain sensing using multi-walled carbon nanotube/epoxy resin films. Following a specific process, the nanocomposite strain gauges with different multi-walled carbon nanotube concentrations were fabricated. The test on these prototypes shows that the multi-walled carbon nanotube/epoxy resin films can respond to wireless electromagnetic excitation by means of generating induced voltage. Experimental measurement also proves that mechanical strain affects the resonant frequencies of the multi-walled carbon nanotube/epoxy resin strain gauges. Therefore, the nanocomposite films can be used to detect mechanical strain wirelessly by calculating the shift of the resonant frequency. Aiming to reveal the working mechanism of the wireless sensing, this study hypothesizes that the nanocomposite strain gauges can be modelled by an equivalent RLC circuit. The subsequent theoretical analysis, and the comparison between the analytical predictions and the experimental results both indicate that the hypothesis is reasonable, since the RLC model can successfully explain the phenomenon of the strain-induced shift of the resonant frequency. The current work provides a promising method to make tag-type wireless strain sensors.

A Short Review on: Recent Advances in the Use of Carbon Nanotubes in Additive Manufacturing of Polymer Matrix Composites

AbstractThe multi‐functionality of polymer matrix composites, proposes remarkable merits over metals including more stiffness and strength, lower weight, higher resistance to corrosion, and fatigue, etc. Furthermore, the next generation of production undergoes a revolution by increasingly progresses in additive manufacturing. There have been a large group of materials that can be exploited for this fashionable fabrication technique, although, polymer matrix composites are a significant class of material that have recently been used in additive manufacturing. The mixture of these polymers with nanofillers such as carbon nanotube improves mechanical, thermal, and electrical conductivity properties. This short review summarizes relevant production techniques, carbon nanotube polymer matrix composites, and performed research on its application for additive manufacturing.

Well-Distributed Polysilsesquioxane-Modified Carbon Nanotubes for Thermal Conductive Insulating Silicone Rubbers

Despite carbon nanotubes (CNTs) have garnered tremendous research interests for enhancing the electrical and thermal conductivity of polymers, it is still a considerable challenge to achieve the uniform dispersion of carbon nanotubes in polymer matrix. Herein, inspired by the mussel-inspired chemistry, we adopted the strategy of coating CNTs with polydopamine. And the polysilsesquioxane-modified CNTs (CNTs-PSQ) were obtained based on the click chemistry reaction. The FT-IR, Raman, XRD, and TGA collectively demonstrated the successful modification of PSQ on the surface of CNTs. The incorporation of PSQ could significantly improve the dispersion of CNTs in the silicon rubbers, and a strong interfacial interaction was formed between CNTs-PSQ and silicon rubber matrix, as observed from TEM images of silicon rubber/CNTs-PSQ nanocomposites. Meanwhile, compared with the nanocomposites with neat CNTs, the ones with CNTs-PSQ exhibited simultaneously improved electrical conductivity and insulating performance. This strategy proposed for the preparation of PSQ-modified CNTs provides insights toward highly insulating and thermal conducting polymers.

Obvious improvement of dispersion of multiwall carbon nanotubes in polymer matrix through careful interface design

AbstractHerein, a simple and effective approach has been proposed to enhance the interfacial strength between multiwall carbon nanotubes (MWCNTs) and polymer matrix for improving the dispersion of MWCNTs. In more detail, a soluble polyaniline derivate containing polar group (POMA) was selectively incorporated into the binary blend of poly(amide‐imide) (PAI) and MWCNTs. The surface energy and atomic force microscope measurements suggested that POMA was located at the interface of PAI and MWCNTs. Fourier transform infrared measurement indicated that POMA simultaneously interacted with MWCNTs and PAI by hydrogen bonding and π–π interaction, providing stronger interfacial strength between conductive filler and polymer matrix. As a result, the dispersion of MWCNTs and the surface roughness of PAI composites were obviously improved, which is helpful for charge and load transfer in the PAI/MWCNTs/POMA ternary films. As a result, the conductivity increased by 250% from 13 S m−1 for PAI/MWCNTs binary composites to 48 S m−1 for PAI/MWCNTs/POMA ternary composites, and the tensile strength increased from 52 MPa for PAI/MWCNTs binary composites to 66 MPa for PAI/MWCNTs/POMA ternary composites. These findings imply that polar aromatic polymers with suitable surface energy will be a desirable compatibilizer for optimizing the dispersion of carbon nanotubes in the polymer matrix.

In situ growth of graphitic carbon nitride on multiwalled carbon nanotubes for interfacial thermal management

This work reports a facile method for in situ growth of graphitic carbon nitride (CN) on surface of multiwalled carbon nanotubes (CNTs), which was performed via the self-assembly of molecular precursors of CN on CNTs and subsequent calcination step. The self-assembly was directed by the hydrogen bonds formed between amino groups of Melamine and carboxyl units of CNTs. After polycondensation reaction, CN nanostructures grew homogeneously on surface of CNTs possibly linked by covalent bonds. The incorporation of CN improved the interfacial properties of CNTs by increasing the functional groups and wettability, which could promote the dispersion of CNTs in polymer matrix and enhance the heat conductive capacity. Accordingly, the obtained thermal conductive silicon grease involving CNTs/CN nanocomposites showed an enhancement in thermal conductivity at a loading amount of CN (~ 8%). Meanwhile, the insulation resistance of the nanocomposites increased significantly with the dose amount of CN due to its semi-conductivity. Therefore, the obtained CNTs/CN nanocomposites were suitable for interfacial thermal management that require high thermal conductivity and electrically insulative properties.

Dual‐Responsive Soft Actuator Based on Aligned Carbon Nanotube Composite/Graphene Bimorph for Bioinspired Applications

AbstractNanocarbon‐based polymer actuators have attracted significant attention because of their excellent actuation performance. In this study, a soft bimorph actuator composed of an anisotropic carbon nanotube (CNT)–polymer composite and reduced graphene oxide (rGO) film is fabricated by a simple blade‐coating method. Owing to the excellent electrical, optical, and thermal properties of the CNT and rGO, the actuator exhibits dual‐responsive actuation. It generates reversible bending deformation with a displacement of ≈13 mm under low electrical voltage stimulation or white light irradiation. Furthermore, because of the embedment of aligned CNTs in polymer matrix, this actuator exhibits excellent mechanical output compared with many of the reported nanocarbon‐based actuators. It can lift a 2.048 g clip to a height of ≈5 mm under low electrical voltage stimulation. Based on this soft actuator with dual response and good mechanical output, various bionic devices are designed. A bionic eagle claw that grasps a soft object under electrical stimulation and an artificial flower blooming in response to light irradiation are constructed. Moreover, a light‐driven smart curtain and a seagull robot are fabricated. These results reveal the great potential of the dual‐responsive anisotropic soft actuator in soft robots and smart devices driven by electricity and light.

Macro-aligned carbon Nanotube–Polymer matrix by dielectrophoresis and transferring process

Single-walled carbon nanotube (SWCNT)-based polymer matrix composites have been developed for various applications such as transparent electrodes and heaters. To enhance the conductivity of the SWCNT/polymer matrix, diverse alignment technologies for the directional alignment of carbon nanoparticles in the polymer matrix have been studied. In the present study, we demonstrate macroscale dielectrophoretic self-alignment of SWCNTs with carboxymethyl cellulose (CMC) using a high alternating current (AC) voltage (150 Vpp, 10kHz) without the use of a semiconductor for the fabrication of electrodes. Owing to the latitudinal alignment of the SWCNTs by the AC field, the resistance values of the SWCNT substrates differ in the directions. Furthermore, transfer of the aligned SWCNTs onto the nitrocellulose (NC) substrate using dimethyl sulfoxide (DMSO) evaporation yields a one-directional multiple aligned SWCNTs/transparent NC sheet that provides approximately 3.3 times higher conductivity than that achieved by alignment in another direction.

Unique approach to debundle carbon nanotubes in polymer matrix using carbon dots for enhanced properties

Excellent dispersion of nanofillers like carbon nanotubes (CNTS) in an aqueous medium of rubber latex through covalent interactions is required to achieve extraordinary reinforcement at very low filler concentration. Herein, aqueous dispersible carbon dots (CDOTS) have been used as dispersion aid to debundle CNTS in carboxylated acrylonitrile butadiene rubber (XNBR) latex. The amine groups of CDOTS have been covalently conjugated with the acid groups of CNTS and XNBR latex through amide bond formation that leads to enhanced interactions between XNBR and CNTS through CDOTS. In addition, CDOTS weaken the strong intertubular van der Waals attraction between the CNTS which results in the efficient dispersion of high aspect ratio CNTS in the XNBR matrix and thereby significantly improves the overall properties. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) studies establish the success of covalent conjugation of CDOTS with CNTS and XNBR latex. The mechanical, dynamic mechanical, thermal stability and thermal conductivity properties of the XNBR-CDOTS-CNTS hybrid nanocomposites are prominently higher when compared to neat XNBR, XNBR-CNTS nanocomposites and XNBR-CDOTS nanocomposites. From transmission electron microscopy (TEM) and atomic force microscopy (AFM) studies it has been ascertained that the CDOTS act as an interconnector between CNTS that prevents agglomeration of CNTS in the XNBR matrix.

STRUCTURAL MODEL OF EFFICIENCY OF COVALENT FUNCTIONALIZATION OF CARBON NANOTUBES

Functionalization of carbon nanotubes (covalent and noncovalent ones) is effective and often applied method of enhancement of their interaction with polymer matrix of nanocomposites. In present work the treatment is proposed, for the first time allowing quantitative estimation of efficiency (quality) of this nanofiller functionalization. For this purpose proposed earlier generalized model was used, taking into consideration characteristics of matrix polymer and nanofiller and also type of the last. Application of the indicated model allows to obtain quantitative characteristic of functionalization efficiency and also elucidation of interconnection of the indicated efficiency with structure of carbon nanotubes in polymer matrix of nanocomposite, namely, with radius of their annular structures. It has been found that the same method of functionalization from the chemical point of view can be changed its efficiency in 20 times that is dependent upon structure (radius) of annular formations of carbon nanotubes. Their specific surface is the more precise characteristic of these formations. This surface serves as indicator of intensity of contact of polymer matrix and surface of nanotubes, which in the end forms mechanical and other properties of the considered nanocomposites. The equation has been obtained, showing the dependence of functionalization efficiency on two parameters: effective specific surface and content of carbon nanotubes. The sharp discrete reduction of functionalization occurs at reaching of percolation threshold of nanofiller. This means that functionalization of local structures of carbon nanotubes is more effective than functionalization of uninterrupted structures of this nanofiller. The most important mechanical property of polymer nanocomposites, namely, the reinforcement degree, is defined unequivocally by efficiency of functionalization. This approach allows making structural prediction of mechanical properties of nanocomposites polymer/carbon nanotube depending of efficiency of nanofiller functionalization.

Reinforcement of Bisphenol-A epoxy resin nanocomposites with noncovalent functionalized and physical adsorption modified CNTs

The depolymerization of carbon nanotubes (CNTs) and dispersion of CNTs in polymer matrix are key to study the application properties of CNTs. We described using the aniline trimer (AT) as a noncovalent dispersant agent and the polyoxyethylene octyl phenyl ether (Triton X-100) as a nonionic surfactant to treat CNTs. UV–vis spectra showed the successful combination of two dispersants and CNTs. Scanning electron microscopy (SEM) analysis showed the dispersion effect was best when the mass ratio of AT to Triton X-100 was 1:1. And we described the preparation of treated-CNTs loaded bisphenol-A epoxy (E44) nanocomposites. We analyzed the fracture surface of nanocomposites by SEM analysis and analyzed the dispersion of CNTs in epoxy matrix by transmission electron microscopy (TEM) analysis. The mechanical properties of neat epoxy resin, raw CNTs loaded epoxy nanocomposites and treated-CNTs loaded epoxy nanocomposites were assessed. The tribological properties and thermodynamic properties of neat epoxy resin and treated-CNTs loaded epoxy nanocomposites were evaluated. The mechanical properties and the tribological properties of the treated-CNTs loaded epoxy nanocomposites were all improved. DSC showed loading treated-CNTs increased the glass temperature. TGA and DTG showed that the thermal stability of nanocomposites was not influenced by loading treated-CNTs.

Influence of different functionalization methods of multi-walled carbon nanotubes on the properties of poly(L-lactide) based nanocomposites

This paper presents influence of the type of carbon nanotube functionalization on properties of poly(L-lactide) (PLLA) based nanocomposite materials. For this purpose surface modifications of multi-walled carbon nanotubes (MWCNTs) were performed by chemical and irradiation techniques, while thermo gravimetric analysis, UV-Visible and Fourier-transform infrared (FT-IR) spectroscopies confirmed successful covalent functionalization. Series of PLLA bionanocom-posites with different contents of functionalized MWCNTs (0.7; 1.6; 2.1 wt%), were synthesized via ring-opening solution polymerisation of L-lactide. FT-IR analysis confirmed that grafting of L-lactide, under controlled condition, is possible to perform starting from the surface of functionalized MWCNTs. From differential scanning calorimetry results it was concluded that even low contents of chemically and irradiation functionalized MWCNTs had a significant effect on thermal properties of the prepared nanocomposites, raising the values of melting and glass transition temperatures. Thermogravimetric analysis (TGA) has shown that the degradation onset temperature for composites with chemically functionalized MWCNTs, was much higher than that for the neat poly(L-lactide) sample and composites with irradiation functionalized MWCNTs. Morphology studies by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that poly(L-lactide) covered surfaces and separated functionalized MWCNTs. Good dispersion of carbon nanotubes in polymer matrix enabled conductivity of synthesized materials, as determined by conductivity tests.

Effect of CNTs dispersion on electrical, mechanical and strain sensing properties of CNT/epoxy nanocomposites

Abstract The remarkable electrical and mechanical properties of carbon nanotubes (CNTs) render CNT-reinforced nanocomposites as potentially attractive materials for strain-sensing and monitoring purposes. The dispersion state of CNTs in polymeric matrix has a significant role on the physical and the mechanical properties of the resulting CNT reinforced nanocomposites. In this study, a series of experiments were designed to investigate the effect of dispersion process parameters and CNT concentration, as well as their interactions on electrical, mechanical and strain sensing properties of CNT/epoxy nanocomposites. Composite samples were produced under different CNT/resin dispersion conditions based on a design of experiments approach, and were characterized using tensile testing, conductivity measurements and micrography. Based on the results, two regression models were established to predict the electric conductivity and the tensile strength of the CNT/epoxy nanocomposites. The robustness and accuracy of the models were verified by implementing verification tests. It was found that the nanocomposites fabricated by dispersing of lower amount of CNT with high mixing speeds and long mixing times had improved sensory properties and were more suitable for strain sensing applications. The effect of post dispersion state on electrical conductivity was also investigated by curing nanocomposites into a magnetic field. A straight forward 2D percolation-based model was used to predict the electrical conductivity and piezoresistivity of the magnetized nanocomposites. Both Experimental and numerical results showed that the electric conductivity could be increased significantly with post dispersing of CNTs using magnetization.

Effect of nanofiller on fibre laser drilling quality of carbon fibre reinforced polymer composite laminates

Laser machining of carbon fibre reinforced polymer composites is a challenging task due to a significant difference between physical and thermal properties of the constituent materials, i.e. polymer matrix and carbon fibres. This results in extended heat-affected zone (HAZ), taper kerf and poor surface finishing. This paper focuses on an investigation, attempting to minimise the divergence in the decomposition temperature of carbon fibres and epoxy resin by adding multi-walled carbon nanotubes in polymer matrix as a secondary reinforcement. High thermal conductivity of multi-walled carbon nanotubes increases the thermal diffusivity of polymer matrix, which in turn reduces the matrix recession. In addition, laser power and scan speed was also considered as an input parameter and their influence on output responses such as HAZ, taper angle and surface roughness has been studied. To analyse the effect of multi-walled carbon nanotubes on the resultant thermal damage, an innovative technique, i.e. scanning acoustic microscopy was used. This technique provides a ply-by-ply damage analysis. C-scans of the top and bottom surface of the machined holes in the composite were also carried out. Further, micrographs of the holes were taken to analyse the quality of the holes using field-emission scanning electron microscope. The obtained results indicated that HAZ, taper angle and surface roughness of holes decreased by ∼30%, ∼47% and ∼43%, respectively, with 1.5 wt% multi-walled carbon nanotubes doped carbon fibre reinforced polymer laminates, when compared with the results obtained from experiments with neat carbon fibre reinforced polymer composite laminates.

Improvement on Dispersion of Carbon Nanotubes in Polymer Matrix by Using the Solvent with a Low Boiling Point

Polymer nanocomposites based on carbon nanotubes attract a great deal of attention recently due to their excellent performance. The dispersion state of CNTs embedded in the matrix is the primary and key issue to realize the potential of the nanocomposite. Here, this paper considers how the boiling point of solvent affects the performance of the nanocomposite when the ultrasonication dispersion method is employed. It is found that solvent with a low boiling point is conducive to save evaporation time so that CNTs can maintain the homogenous dispersion state as much as possible after ultrasonication. Therefore, the stretchability and tensile strength can be improved, while the electrical conductivity has an obvious enhancement as well.

Enhancing water flux through semipermeable polybenzimidazole membranes by adding surfactant‐treated CNTs

ABSTRACTIn this study, surfactant‐treated carbon nanotubes (CNTs) were incorporated into polybenzimidazole (PBI) matrix to prepare the PBI/CNT composite membranes with CNT content in the range of 0 to 15 wt %. The composite membranes were fabricated by spin‐coating. The membrane morphology, mechanical property, and water and salt transport properties were investigated to characterize the additive effect of CNTs. The tensile strength of all the PBI/CNT composite membranes was lower than that of pristine PBI membrane, indicating the weak interaction between CNT and PBI. In addition, water flux increased without reducing the salt rejection when CNTs were homogeneously dispersed in the PBI matrix at a less than 7.5 wt % content. On the other hand, at 10 wt % and higher CNT content, submicro‐scaled cellular structure was formed, and both the water flux and salt rejection decreased. The well‐dispersed CNTs in the PBI matrix via weak interaction preferentially improve the water permeability by 1.7 times without depressing the salt rejection. The incorporation of well‐dispersed CNTs in polymer matrix provides a promising and facile option for improvement in the water transport properties through the polymeric semipermeable membranes with intrinsically low water permeability such as PBI. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45875.

Improving Thermal and Flame Retardant Properties of Epoxy Resin with Organic NiFe‐Layered Double Hydroxide‐Carbon Nanotubes Hybrids

To improve the dispersion of carbon nanotubes (CNTs) and flame retardancy of layered double hydroxide (LDH) in epoxy resin (EP), organic nickel‐iron layered double hydroxide (ONiFe‐LDH‐CNTs) hybrids were assembled through co‐precipitation. These hybrids were further used as reinforcing filler in EP. EP/ONiFe‐LDH‐CNTs nanocomposites containing 4 wt% of ONiFe‐LDH‐CNTs with different ratios of ONiFe‐LDH and CNTs were prepared by ultrasonic dispersion and program temperature curing. The structure and morphology of the obtained hybrids were characterized by different techniques. The dispersion of nanofillers in the EP matrix was observed by transmission electron microscopy (TEM). The results revealed a coexistence of exfoliated and intercalated ONiFe‐LDH‐ CNTs in polymer matrix. Strong combination of the above nanofillers with the EP matrix provided an efficient thermal and flame retardant improvement for the nanocomposites. It showed that EP/ONiFe‐LDH‐CNTs nanocomposites exhibited superior flame retardant and thermal properties compared with EP. Such improved thermal properties could be attributed to the better homogeneous dispersion, stronger interfacial interaction, excellent charring performance of ONiFe‐LDH and synergistic effect between ONiFe‐LDH and CNTs.

Polymer Composite Containing Carbon Nanotubes and their Applications.

Carbon nanotubes (CNTs) are attractive nanostructures in this regard, primarily due to their high aspect ratio coupled with high thermal and electrical conductivities. Consequently, CNT polymer composites have been extensively investigated for various applications, owing to their light weight and processibility. However, there have been several issues affecting the utilization of CNTs, such as aggregation (bundling) which leads to a non-uniform dispersion and poor interfacial bonding of the CNTs with the polymer, resulting in variation in composite performance, along with the additional issue of high cost of CNTs. In this article, recent research and patents for polymer composites containing carbon nanomaterial are presented and summarized. In addition, a rationale for optimally designed carbon nanotube polymer composites and their applications are suggested. Above the electrical percolation threshold, a transition from insulator to conductor occurs. The percolation threshold values of CNT composite are dependent on filler shape, intrinsic properties of filler, type of polymer, CNT dispersion condition and so on. Different values of percolation threshold CNT polymer composites have been summarized. The difference in percolation threshold and conductivity of CNT composites could be explained by the degree of effective interactions between nanotubes and polymer matrix. The reaction between surface functional groups of CNTs and polymer could contribute to better dispersion of CNTs in polymer matrix. Consequently, it increased the number of electrical networks of CNTs in polymer, resulting in an enhancement of composite conductivity. In addition, to exfoliate nanotubes from heavy bundles, ultrasonication with proper solvent and three roll milling processes were used. Potential reactions of covalent bonding between functionalized CNTs and polymer were suggested based on the above rationale. Through the use of CNT functionalization, high aspect ratio CNTs, and proper fabrication, uniform dispersion of nanotubes in polymer can be achieved leading to considerable improvement in electrical conductivity and electromagnetic interference (EMI) shielding properties.

Impact of the carbon nanotube reinforcement in glass/epoxy polymeric nanocomposite on the quality of fiber laser drilling

In this work, the influence of multi-walled carbon nanotube is presented on laser drilling of multi-walled carbon nanotube–doped glass/epoxy polymeric nanocomposite. Multi-walled carbon nanotubes were dispersed in polymer matrix to improve the thermal conductivity and heat transfer characteristics of materials, which also reduces the divergence in decomposition temperature of matrix and glass fiber. Effect of carbon nanotube on laser drilling–induced damages was assessed by considering heat-affected zone, taper angle, and surface roughness as output parameters. Scanning acoustic microscopy showed the useful technique to examine the laser drilling damage around the hole by providing ply-by-ply damage analysis. In addition, scanning electron microscope provided more details to better analyze the machining quality of laser-drilled hole. Energy dispersive X-ray analysis provided the elemental analysis of charred material which is deposited on the hole wall. Obtained results indicate that the quality of hole was improved significantly due to addition of multi-walled carbon nanotube in polymer matrix.

Thermo-mechanical and anti-corrosive properties of MWCNT/epoxy nanocomposite fabricated by innovative dispersion technique

Abstract To obtain cluster free homogeneous dispersion of carbon nanotubes in polymer matrix, variety of strategies were applied. In the present work, we report a systematic approach to obtain a superior level of dispersion of multi-walled carbon nanotubes (MWCNTs) in epoxy by applying simultaneously ultrasonic waves and shear force generated by axial flow impeller. The influence of dispersion of MWCNTs on anti-corrosion, mechanical and thermal properties of MWCNT/epoxy nanocomposite was investigated. Field Emission Scanning Electron Microscopy (FESEM) studies confirmed cluster free uniform dispersion of MWCNTs in epoxy matrix, which lead to enhanced tensile strength by 35%, toughness by 53% and storage modulus by 35% on loading of 0.75 wt% of MWCNTs in epoxy. It was found that when mild steel was coated with MWCNT/epoxy nanocomposite (0.75 wt%), the corrosion rate decreased upto 2.5 × 10 −3 MPY and protection efficiency increased upto 99.99%.