Mechanical properties of plasma‐treated carbon fiber reinforced PTFE composites with CNT

This paper is concerned with the effects of the plasma surface treatment and the addition of CNT on the mechanical properties of carbon fiber/polytetrafluoroethylene (PTFE) composite. The tensile and flexural strength of composites containing CNT and plasma‐treated carbon fibers improved. The flexural strength first decreases with respect to the CF content. The flexural strength increases to 179 MPa for the plasma‐treated composite as compared with 167 MPa for the neat carbon fiber composites. The overall improvement is thus nearly 8%.     

Thermal transfer,interfacial, and mechanical properties of carbon fiber/polycarbonate-CNT composites using infrared thermography

Electrical resistance (ER) and thermogram measurements were used to evaluate thermal transfer, interfacial and mechanical properties of carbon fiber reinforced thermoplastic polycarbonate composites. Carbon nanotubes (CNTs) were fairly uniformly dispersed in polycarbonates using a solvent dispersion method. The CNTs were then further dispersed with an additional time using a twin screw extruder. The effect of CNT on the mechanical properties of polycarbonate was evaluated using a thin film tensile test. For thermogram to evaluate the transferring temperature the composite was placed on a hotplate and copper wires were inserted in the composite at uniform thickness intervals. Due to the different inherent thermal conductivity of CNT, ER was measured to detect thermal changes in the carbon fiber/CNT-polycarbonate composites. The comparison of interlaminar shear strength (ILSS) was to investigate effects of CNT on mechanical and interfacial properties. The uniform distribution of CNTs affected all of these properties in carbon fiber-reinforced thermoplastic composite. Furthermore, heat transfer and heat release become more rapid with the addition of CNT than the without case.     

Enhanced Nucleation and Crystallization in PLA/CNT Composites via Disperse Orange 3 with Corresponding Improvement in Nanomechanical Properties

The potential for the material property improvement through the addition of carbon nanotubes (CNTs) in composite materials is often limited due to CNT agglomeration. In this work, Disperse Orange 3 (DO3) was investigated to determine its effectiveness in dispersing CNTs in a poly (lactic acid) (PLA) matrix. First, adsorption studies of DO3 onto CNTs were performed to determine the appropriate amount of DO3 to add so that the CNT surface will be nearly saturated with DO3 while limiting the excess DO3 dissolved in the polymer. The resultant improvements in the mechanical properties were determined via nanoindentation. Highly stable dispersion of CNTs in tetrahydrofuran with DO3 was observed 72 hours after sonication. Scanning electron microscopy confirmed that DO3‐functionalized CNTs were able to separate and disperse well inside of the PLA matrix. Addition of DO3 to the nanocomposite resulted in an increase in the glass transition temperature and crystallinity of the composite due to the more effective dispersion of the nanofiller which serves as a nucleation agent. The CNTs treated with DO3 also increased the elastic modulus and hardness of the composite compared to neat PLA and untreated PLA‐CNT composites. From this study, DO3 was demonstrated to be an effective dispersing agent in the solvent and the PLA matrix which allowed for enhanced crystallization and improved nanomechanical properties in the resultant composite.     

Effect of nanosized carbon black on thermal stability and flame retardancy of polypropylene/carbon nanotubes nanocomposites

Nanosized carbon black (CB) was introduced into polypropylene/carbon nanotubes (PP/CNTs) nanocomposites to investigate the effect of multi‐component nanofillers on the thermal stability and flammability properties of PP. The obtained ternary nanocomposites displayed dramatically improved thermal stability compared with neat PP and PP/CNTs nanocomposites. Moreover, the flame retardancy of resultant nanocomposites was greatly improved with a significant reduction in peak heat release rate and increase of limited oxygen index value, and it was strongly dependent on the content of CB. This enhanced effect was attributed mainly to the formation of good carbon protective layers by CB and CNTs during combustion. Rheological properties further confirmed that CB played an important role on promoting the formation of crosslink network on the base of PP/CNTs system, which were also responsible for the improved thermal stability and flame retardancy of PP. Copyright © 2013 John Wiley & Sons, Ltd.     

A Review Featuring Fabrication,Properties and Applications of Carbon Nanotubes (CNTs) Reinforced Polymer and Epoxy Nanocomposites

Carbon nanotubes (CNTs) have long been recognized as the stiffest and strongest man-made material known to date.In addition,their high electrical conductivity has roused interest in the areas of electrical appliances and communication related applications.However,due to their miniature size,the excellent properties of these nanostructures can only be exploited if they are homogeneously embedded into light-weight matrices as those offered by a whole series of engineering polymers.In order to enhance their chemical affinity to engineering polymer matrices,chemical modification of the graphitic sidewalls and tips is necessary.The mechanical and electrical properties to date of a whole range of nanocomposites of various carbon nanotube contents are also reviewed in this attempt to facilitate progress in this emerging area.Recently,carbonaceous nano-fillers such as graphene and carbon nanotubes (CNTs) play a promising role due to their better structural and functional properties and broad range of applications in every field.Since CNTs usually form stabilized bundles due to van der Waals interactions,they are extremely difficult to disperse and align in a polymer matrix.The biggest issues in the preparation of CNTs reinforced composites reside in efficient dispersion of CNTs into a polymer matrix,the assessment of the dispersion,and the alignment and control of the CNTs in the matrix.An overview of various CNT functionalization methods is given.In particular,CNT functionalization using click chemistry and the preparation of CNT composites employing hyperbranched polymers are stressed as potential techniques to achieve good CNT dispersion.In addition,discussions on mechanical,thermal,electrical,electrochemical and applications ofpolymer/CNT composites are also included.     

Morphology,rheological and crystallization behavior in non-covalently functionalized carbon nanotube reinforced poly(butylene succinate) nanocomposites with low percolation threshold

Multi-walled carbon nanotubes (CNTs) were non-covalently functionalized by surface wrapping of poly(sodium 4-styrenesulfonate) (PSS) with the aid of ultrasound. The functionalized CNTs were incorporated into poly(butylene succinate) (PBS) through solution coagulation to fabricate CNTs filled PBS nanocomposites. The morphologies of the PBS/CNT nanocomposites were studied by scanning electron microscope (SEM) and transmission electron microscope (TEM), and the effect of loading of functionalized CNT on the rheological behavior, electrical conductivity and mechanical properties of the nanocomposites was investigated systemically. SEM observation indicates that functionalized CNTs dispersed in PBS matrix without obvious aggregation and showed good interfacial adhesion with the PBS phase. TEM observation reveals that a CNT network was formed when the loading of CNTs increased from 0.1 to 0.3 wt%. Rheological investigation indicates the formation of a CNT network with a percolation threshold of only 0.3 wt%. Significant improvement in electrical conductivity occurred at CNT loading of 0.3 wt%, with the value of electrical conductivity increasing by six orders of magnitude compared to neat PBS. Differential scanning calorimetry indicates that the melt crystallization temperature of PBS was improved by ∼14 °C with addition of only 0.05 wt% functionalized CNTs. Tensile tests indicate that both the yield strength and Young's modulus of PBS were apparently reinforced by incorporation of functionalized CNTs, while the elongation at break was reduced gradually.     

Properties of ethylene propylene diene rubber/white and black filler composites cured by gamma radiation in presence of sorbic acid

The effect of incorporating sorbic acid (SA), an echo-friendly curing agent, and silica or carbon black (CB) filler, as well as gamma irradiation on the physico-chemical, mechanical and thermal properties of ethylene propylene diene monomer rubber (EPDM) was investigated. The results indicated that the developed composites revealed improvement in the studied parameters over the untreated samples. Filler incorporation into rubber matrix has been proven a key factor in enhancing the swelling resistance, tensile strength and thermal properties of the fabricated composites. The improvement in tensile strength and modulus was attributed to better interfacial bonding via SA. Alternatively, a comparison was established between the performance of the white and black fillers. The utmost mechanical performance was reported for the incorporated ratios 10 phr SA and 40 phr white filler into a 50 kGy irradiated composite. Meanwhile, the incorporation of CB yielded better thermally stable composites than those filled with silica at similar conditions.     

The mechanical properties of plasma‐treated carbon fiber reinforced PA6 composites with CNT

The aim of this work is the evaluation of the effects of plasma treatment and the addition of CNT on the mechanical properties of carbon fibre/PA6 composite. A powder impregnation process with integrated inline continuous plasma of carbon fibers was used to produce CF/PA6 composite. CF/PA6 composite was processed into test laminates by compression moulding, and interface dominated composite properties were studied. The tensile and impact strength of composites containing CNT and plasma‐treated carbon fibres improved obviously. The tensile strength of nanocomposite largely increases with the increasing of the CNT content and then decreases when the CNT content is over 2%. The hydroxyl groups of the fibers surface are in favor of the wettability of carbon fibers by the polar matrix resin, which is resulting in a further interaction of the fiber surface with the curing system of the matrix resin.     

Carbon Nanotubes/Heteroatom‐Doped Carbon Core–Sheath Nanostructures as Highly Active,Metal‐Free Oxygen Reduction Electrocatalysts for Alkaline Fuel Cells

A facile, scalable route to new nanocomposites that are based on carbon nanotubes/heteroatom‐doped carbon (CNT/HDC) core–sheath nanostructures is reported. These nanostructures were prepared by the adsorption of heteroatom‐containing ionic liquids on the walls of CNTs, followed by carbonization. The design of the CNT/HDC composite allows for combining the electrical conductivity of the CNTs with the catalytic activity of the heteroatom‐containing HDC sheath layers. The CNT/HDC nanostructures are highly active electrocatalysts for the oxygen reduction reaction and displayed one of the best performances among heteroatom‐doped nanocarbon catalysts in terms of half‐wave potential and kinetic current density. The four‐electron selectivity and the exchange current density of the CNT/HDC nanostructures are comparable with those of a Pt/C catalyst, and the CNT/HDC composites were superior to Pt/C in terms of long‐term durability and poison tolerance. Furthermore, an alkaline fuel cell that employs a CNT/HDC nanostructure as the cathode catalyst shows very high current and power densities, which sheds light on the practical applicability of these new nanocomposites.     

Carbon Nanotubes/Heteroatom‐Doped Carbon Core–Sheath Nanostructures as Highly Active,Metal‐Free Oxygen Reduction Electrocatalysts for Alkaline Fuel Cells

A facile, scalable route to new nanocomposites that are based on carbon nanotubes/heteroatom‐doped carbon (CNT/HDC) core–sheath nanostructures is reported. These nanostructures were prepared by the adsorption of heteroatom‐containing ionic liquids on the walls of CNTs, followed by carbonization. The design of the CNT/HDC composite allows for combining the electrical conductivity of the CNTs with the catalytic activity of the heteroatom‐containing HDC sheath layers. The CNT/HDC nanostructures are highly active electrocatalysts for the oxygen reduction reaction and displayed one of the best performances among heteroatom‐doped nanocarbon catalysts in terms of half‐wave potential and kinetic current density. The four‐electron selectivity and the exchange current density of the CNT/HDC nanostructures are comparable with those of a Pt/C catalyst, and the CNT/HDC composites were superior to Pt/C in terms of long‐term durability and poison tolerance. Furthermore, an alkaline fuel cell that employs a CNT/HDC nanostructure as the cathode catalyst shows very high current and power densities, which sheds light on the practical applicability of these new nanocomposites.     

Thermal,mechanical and electroactive shape memory properties of polyurethane (PU)/poly (lactic acid) (PLA)/CNT nanocomposites

Polymer blend nanocomposites based on thermoplastic polyurethane (PU) elastomer, polylactide (PLA) and surface modified carbon nanotubes were prepared via simple melt mixing process and investigated for its mechanical, dynamic mechanical and electroactive shape memory properties. Chemical and structural characterization of the polymer blend nanocomposites were investigated by Fourier Transform infrared (FT-IR) and wide angle X-ray diffraction (WAXD). Loading of the surface modified carbon nanotube in the PU/PLA polymer blends resulted in the significant improvement on the mechanical properties such as tensile strength, when compared to the pure and pristine CNT loaded polymer blends. Dynamic mechanical analysis showed that the glass transition temperature (T_g) of the PU/PLA blend slightly increases on loading of pristine CNT and this effect is more pronounced on loading surface modified CNTs. Thermal and electrical properties of the polymer blend composites increases significantly on loading pristine or surface modified CNTs. Finally, shape memory studies of the PU/PLA/modified CNT composites exhibit a remarkable recoverability of its shape at lower applied dc voltages, when compared to pure or pristine CNT loaded system.     

微波调控石墨烯-碳纳米管协同增强聚氨酯损伤自修复研究

首先采用溶液共混法制备出石墨烯-碳纳米管(G-CNT)/聚氨酯(TPU)复合材料,然后通过拉伸实验及扫描电子显微镜(SEM)表征来考察该材料的拉伸强度和微波自修复特性,并从力学及材料与微波之间的相互作用等角度对其拉伸强度增强和微波修复机理进行研究.结果表明:在拉伸强度方面,与单一的石墨烯或CNT增强TPU相比,G-CNT之间形成的协同效应使TPU拉伸强度得到进一步提高,当石墨烯和CNT的质量比为3∶1时,G-CNT/TPU抗拉强度较纯TPU提高了67%,较G/TPU提高了18%,较CNT/TPU提高了25%;在材料裂纹的微波修复方面,石墨烯和CNT之间的协同效应使TPU材料自修复效果得到有效提高,当石墨烯和CNT的质量比为3∶1时,G-CNT/TPU修复效果达到最高值117%.     

Effect of the Nanotube Radius and the Volume Fraction on the Mechanical Properties of Carbon Nanotube-Reinforced Aluminum Metal Matrix Composites

By using the advantages of carbon nanotubes (CNTs), such as their excellent mechanical properties and low density, CNT-reinforced metal matrix composites (MMCs) are expected to overcome the limitations of conventional metal materials, i.e., their high density and low ductility. To understand the behavior of composite materials, it is necessary to observe the behavior at the molecular level and to understand the effect of various factors, such as the radius and content of CNTs. Therefore, in this study, the effect of the CNT radius and content on the mechanical properties of CNT-Al composites was observed using a series of molecular dynamics simulations, particularly focusing on MMCs with a high CNT content and large CNT diameter. The mechanical properties, such as the strength and stiffness, were increased with an increasing CNT radius. As the CNT content increased, the strength and stiffness increased; however, the fracture strain was not affected. The behavior of double-walled carbon nanotubes (DWNTs) and single-walled carbon nanotubes (SWNTs) was compared through the decomposition of the stress–strain curve and observations of the atomic stress field. The fracture strain increased significantly for SWNT-Al as the tensile force was applied in the axial direction of the armchair CNTs. In the case of DWNTs, an early failure was initiated at the inner CNTs. In addition, the change in the elastic modulus according to the CNT content was predicted using the modified rule of mixture. This study is expected to be useful for the design and development of high-performance MMCs reinforced by CNTs.     

Preparation and mechanical properties of water-dispersible hyperbranched polymer grafted carbon black/natural rubber composites by latex blending method

In order to improve the mechanical properties of rubber-matrix composites, carboxyl-terminated hyperbranched poly (2-hydroxypropane-1,2,3-tricarboxylic acid) grafted carbon black (CB-g-CTHBP) was prepared, and it could be stably dispersed in water for up to 90 days. CB-g-CTHBP dispersion and natural rubber latex were blended to obtain NR/CB-g-CTHBP, and the effect of CB-g-CTHBP content on the mechanical properties of composites was discussed. The results show that the dispersibility and wettability of CB-g-CTHBP to composites are significantly improved after grafting hyperbranched polymer onto the surface. Compared with the composite filled with NR/CB, when the amount of filler is 30 phr, tensile strength, tear strength, and shore A hardness of NR/CB-g-CTHBP increase by 54.78%, 55.13%, and 20.96%, respectively. Moreover, CB-g-CTHBP could disperse more evenly in the natural rubber-matrix, and the interaction between CB-g-CTHBP and rubber-matrix could further enhance in the composite.     

聚苯乙烯/碳纳米管复合材料研究进展

聚苯乙烯/碳纳米管复合材料是近年来开发的新型聚合物基复合材料,具有独特的一维纳米管分散微结构,往往表现出比纯聚苯乙烯更好的机械力学性能、电学性能和热性能等,在诸多领域具有广泛的应用前景.本文首先简要介绍了碳纳米管的结构特点、制备与纯化和性能,然后重点阐述了聚苯乙烯/碳纳米管复合材料的几种制备方法、结构表征以及力学、电学和热性能等方面的研究进展,并对聚苯乙烯共聚物/碳纳米管复合材料的研究现状进行介绍.     

原位接枝炭黑/天然橡胶复合材料的制备及性能

采用原位固相接枝方法,使在高温和强剪切作用下降解的天然橡胶接枝到炭黑表面.通过对接枝前后炭黑填充天然橡胶的性能对比发现,原位接枝炭黑不但能提高天然橡胶的硫化速度,还能提高拉伸强度,定伸应力和撕裂强度等;动态力学性能的测试结果表明接枝炭黑填充的天然橡胶中接枝炭黑网络化程度较低,这些结果主要归因于接枝炭黑在橡胶基体中分散性的改善及炭黑与橡胶之间作用力的增加.     

Facile approach to obtain individual‐nanotube dispersion at high loading in carbon nanotubes/polyimide composites

A big challenge in making a composite lies in achieving individual‐nanotube dispersion of carbon nanotubes (CNTs) in a polymer matrix, without aggregation and entanglement and excellent interfacial adhesion between the CNTs and the polymers matrix. In this communication, using polyethylene glycol‐200, we successfully prepared CNT‐reinforced polyimide composites that exhibit individual‐nanotube dispertion in the matrix at high‐loading CNT's. The content of CNTs in a composite can reach 43 wt%. Copyright © 2007 John Wiley & Sons, Ltd.     

Thermal curing behavior of MWCNT modified vinyl ester‐polyester resin suspensions prepared with 3‐roll milling technique

This study aims to investigate the curing behavior of a vinyl ester‐polyester resin suspensions containing 0.3 wt % of multiwalled carbon nanotubes with and without amine functional groups (MWCNTs and MWCNT‐NH₂). For this purpose, various analytical techniques, including Differential Scanning Calorimetry (DSC), Fourier infrared spectroscopy (FTIR), Raman Spectroscopy, and Thermo Gravimetric Analyzer (TGA) were conducted. The resin suspensions with carbon nanotubes (CNTs) were prepared via 3‐roll milling technique. DSC measurements showed that resin suspensions containing CNTs exhibited higher heat of cure (Q), besides lower activation energy (E_a) when compared with neat resin. For the sake of simplicity of interpretation, FTIR investigations were performed on neat vinyl ester resin suspensions containing the same amount of CNTs as resin. As a result, the individual fractional conversion rates of styrene and vinyl ester were interestingly found to be altered dependent on MWCNTs and MWCNT‐NH₂. The findings obtained from RS measurements of the cured samples are highly proportional to those obtained from FTIR measurements. TGA measurements revealed that CNT modified nanocomposites have higher activation energy of degradation (E_d) compared with the cured polymer. The findings obtained revealed that CNTs with and without amine functional groups alter overall thermal curing response of the surrounding matrix resin, which may probably impart distinctive characteristics to mechanical behavior of the corresponding nanocomposites achieved. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1511–1522, 2009     

Shape memory behavior of carbon nanotube‐reinforced trans‐1,4‐polyisoprene and low‐density polyethylene composites

Shape memory composites of trans‐1,4‐polyisoprene (TPI) and low‐density polyethylene (LDPE) with easily achievable transition temperatures were prepared by a simple physical blending method. Carbon nanotubes (CNTs) were introduced to improve the mechanical properties of the TPI/LDPE composites. The mechanical, cure, thermal, and shape memory properties of the TPI/LDPE/CNTs composites were investigated in this study. In these composites, the cross‐linked network generated in both the TPI and LDPE portions acted as a fixed domain, while the crystalline regions of the TPI and LDPE portions acted as a domain of reversible shape memory behavior. We found that CNTs acted as not only reinforced fillers but also nucleation agents, which improved the crystalline degree of the TPI and LDPE portions of the composites. Compared with the properties at the other CNT doses, the mechanical properties of the TPI/LDPE composites when the CNT dose was 1 phr were improved significantly, showing excellent shape memory properties (R_f = 97.85%, R_r = 95.70%).     

The effect of a semi‐industrial masterbatch process on the carbon nanotube agglomerates and its influence in the properties of thermoplastic carbon nanotube composites

This study details an industrial process to prepare polypropylene (PP) composites reinforced with different loadings (0.5–10wt.%) of carbon nanotubes (CNTs) from a direct dilution of a masterbatch produced by an optimized extrusion compounding process. The work demonstrates how the anisotropy in the distribution of CNTs can have a positive effect on the electrical conductivity and fracture toughness of the resulting composites. The composite with the highest loading of CNTs had an electrical conductivity of 10^?2 S/m comparable with those reported in the available literature. The composites showed anisotropy in their properties that seems to be caused by the non‐homogeneous distribution of the agglomerates produced by the orientation of the flow direction during the injection process. The composites produced in this work exhibited a fracture toughness up to 55% higher than neat PP and failed by polymer ductile tearing. It was found that the CNT agglomerates distributed throughout the matrix increased the toughness of PP by promoting plastic deformation of the matrix during the fracture process and by a slight load transfer between the polymer matrix and the CNTs of the agglomerates. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 189–197