Carbon Nanotube Composite Fibers Research Articles

Oxygen Reduction on Catalysts Prepared by Pyrolysis of Electrospun Styrene–Acrylonitrile Copolymer and Multi-walled Carbon Nanotube Composite Fibres

For the first time, the oxygen reduction reaction (ORR) is studied on pyrolysed electrospun multi-walled carbon nanotube (MWCNT) and styrene–acrylonitrile (SAN) composite fibre catalysts in alkaline medium. Scanning electron microscopy images revealed that the prepared catalysts mainly consist of MWCNTs, while nitrogen doping of the catalysts is confirmed by X-ray photoelectron spectroscopy. This indicates that SAN can be used as a nitrogen precursor. The ORR studies carried out by rotating disc electrode (RDE) and rotating ring-disc electrode (RRDE) methods showed that the prepared catalysts were considerably more active towards the ORR than the pristine MWCNTs.

Fiber-based MnO2/carbon nanotube/polyimide asymmetric supercapacitor

With the development of wearable electronics, fiber-based supercapacitors with both high energy and power densities are under growing demand. Herein we discovered a high performance fiber-based asymmetric supercapacitor (FAS) based on two carbon nanotube (CNT) composite fibers. MnO2 nanosheets were in situ grown on a CNT fiber to serve as the positive electrode, while polyimide was deposited onto another CNT fiber to form the negative electrode. The resulting aqueous FAS demonstrated broad operating voltage window (0–2.1 V), high areal energy density (36.4 μWh cm−2 at power density of 0.78 mW cm−2) and high power density (15.6 mW cm−2 at energy density of 30.2 μWh cm−2) with good rate performance, long cycling life and high flexibility.

Chitosan surface modified electrospun poly(ε-caprolactone)/carbon nanotube composite fibers with enhanced mechanical, cell proliferation and antibacterial properties

The surface modification is one of the most effective methods to improve the bioactivity and cell affinity effect of electrospun poly(ε-caprolactone) (PCL) fibers. In the present study, chitosan (CS), a cationic polysaccharide, was used to modify the surface of electrospun PCL fibers. To obtain strong interaction between CS and PCL fibers, negatively charged PCL fibers were prepared by the incorporation of acid-treated carbon nanotubes (CNTs) into the fibers. In this way, the positively charged chitosan could be immobilized onto the surface of PCL fibers tightly by the electrostatic attraction. Besides, the incorporation of CNTs could significantly improve the mechanical strength of electrospun PCL fibers even after the CS modification, which guaranteed their usability in practical applications. The CS modification could effectively improve the wettability and bioactivity of electrospun PCL fibers. Cultivation of L929 fibroblast cells on the obtained fibers and the antibacterial activity were both evaluated to discuss the influence of chitosan modification. The results indicated that this modification could enhance the cell proliferation and antibacterial ability in comparison to the non-modified groups.

Reinforcement efficiency of carbon nanotubes and their effect on crystal-crystal slip in poly(ether ketone)/carbon nanotube composite fibers

Poly(ether ketone) (PEK)/carbon nanotube (CNT) composite fibers have been produced using dry-jet wet spinning. Carbon nanofibers (CNF), few-walled carbon nanotubes (FWNT), and multi-walled nanotubes (MWNT) have been utilized as nanofillers, with few-walled carbon nanotube loadings as high as 28 wt%. The interfacial strength of the PEK/FWNT and PEK/MWNT fibers were evaluated through the monitoring of the G-mode Raman peak shift as a function of fiber strain. Interfacial shear strengths as high as 14.2 MPa were measured for the PEK/FWNT fiber with 28 wt% CNT loading, a 1320% increase as compared to the PEK/MWNT fiber with 5 wt% loading (1.0 MPa). Tg of the PEK/FWNT fibers increased by 19 °C as the FWNT loading was increased from 5 wt% to 28 wt%. A second peak in the tan δ behavior of all PEK/CNT fibers was also observed. This second tan δ peak (T ∼ 240 °C–250 °C) is attributed to the α*-transition (crystal-crystal slip) in the PEK crystalline regions, and its presence is more pronounced (higher magnitude of tan δ) in all PEK/FWNT fibers as compared to PEK/MWNT and PEK/CNF fibers. FWNTs are restricting the mobility of the amorphous PEK as evidenced by the increasing Tg. Enhanced PEK crystal-crystal slip corresponds to increasing large scale chain mobility in the crystalline regions of the PEK at Tα*. We propose a model which correlates the increase in PEK-FWNT interfacial shear strength to an increase in large scale chain mobility where crystal-crystal slip precedes failure of PEK/CNT interface at Tα* for the PEK/FWNT fibers.

Application of polyaniline–multiwalled carbon nanotubes composite fiber for determination of benzaldehyde in injectable pharmaceutical formulations by solid-phase microextraction GC–FID using experimental design

A polyaniline–multiwalled carbon nanotubes composite fiber was electrodeposited onto a platinum wire using cyclic voltammetry. This fiber was used for headspace solid-phase microextraction combined with gas chromatography and flame ionization detector of trace levels of benzaldehyde in some injectable pharmaceutical formulations. Three solid-phase microextraction parameters including temperature, time and stirring rate were investigated simultaneously using a three-level-three-factor Box–Behnken as experimental design on the extraction capability. The as-made fiber has a lifetime of over 300 extractions without any obvious decline in extraction efficiency. At the optimum conditions (extraction temperature 60°C, extraction time 15 min, stirring rate 700 rpm), the method displays excellent linearity over the concentration range of 25–1000 ng/mL of benzaldehyde with RSD values ranging from 1.0 to 6.8%. The limits of quantitation and detection were 25 and 10 ng/mL, respectively.

Mechanical properties of polyimide/multi-walled carbon nanotube composite fibers

A series of polyimide (PI)/multi-walled carbon nanotube (MWCNT) composite fibers were prepared by copolymerizing a mixture of monomers and carboxylic-functionalized MWCNTs, followed by dry-jet wet spinning, thermal imidization, and hot-drawing process. The content of the carboxylic groups of MWCNTs significantly increased when treated with mixed acid, whereas their length decreased with treatment time. Both the carboxylic content and length of MWCNTs influenced the mechanical properties of the composite fibers. Fiber added with 0.1 wt% MWCNTs treated for 4 h exhibited the best mechanical properties, i.e., 1.4 GPa tensile strength and 14.30% elongation at break, which were 51% and 32% higher than those of pure PI fibers, respectively. These results indicated that a suitable MWCNT content strengthened and toughened the resultant PI composite fibers, simultaneously. Moreover, raising draw ratio resulted in the increase of tensile strength and tensile modulus of the composite fibers.

Electrospun Poly(lactic-co-glycolic acid)/Multiwalled Carbon Nanotube Nanofibers for Cardiac Tissue Engineering

Many conductive scaffolds were fabricated to mimic the topography of the cardiac microenvironment in vitro in order to improve the performance of engineered cardiac tissues. This study fabricated aligned poly(lactic-co-glycolic acid)/multiwalled carbon nanotube fibers by electrospinning. The Young's modulus and conductivity were significantly greater on poly(lactic-co-glycolic acid) fibers with 3% multiwalled carbon nanotubes compared to others. Topographical cues and conductivity were applied to investigate the combined effect on cardiomyocyte behavior. Neonatal rat cardiomyocytes cultured on the conductive fibers maintained their viability, induced cell elongation, and enhanced sarcomeric α-actinin and troponin I production in cardiomyocytes. The results indicate that poly(lactic-co-glycolic acid)/multiwalled carbon nanotube composite fibers have great potential for cardiac tissue engineering.

Study on the preparation of hyperbranched polyethylene fibers and hyperbranched polyethylene composite fibers via electrospinning

ABSTRACTThis contribution mainly studied the preparation of hyperbranched polyethylene (HBPE) fibers and HBPE/multiwalled carbon nanotube (MWCNT) composite fibers via electrospinning for the first time. Firstly, the effects of solvents, solution concentration, voltage, and rotating speed of collector on the morphology of HBPE fibers were studied. Among the factors, solvent type, concentration, and voltage showed notable influence on the morphology of HBPE fibers. HBPE has an excellent dispersion effect on CNT in organic solvents. Through ultrasonic dispersion, the HBPE solutions with dispersed MWCNT were obtained. Then HBPE/MWCNT composite fibers were obtained with different contents of MWCNT via electrospinning. The effects of voltage and working distance on the morphology of HBPE/MWCNT composite fibers were investigated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42517.

Enhancement of the tensile strength in poly(p-phenylene sulfide) and multi-walled carbon nanotube nanocomposites by hot-stretching

The interfacial adhesion is a significant factor for improving mechanical properties of filler-reinforced polymer composites. In this work, the as-spun and hot-stretched poly(phenylene sulfide) (PPS) and multi-walled carbon nanotubes (MWCNTs) composite fibers were prepared. Tensile test showed that large enhancements in tensile strength and modulus were achieved in hot-stretched samples. The strong interfacial interaction leading to the effective load transferring was realized in hot-stretched composite fibers. Further analysis showed that the strong interfacial adhesion might be the result of the formation of π–π interaction between the benzene ring of PPS and the surface of MWCNTs with the help of hot-stretching, which could be the most important reason for the remarkable mechanical enhancement of the hot-stretched composite fibers.

The plasticized spinning and cyclization behaviors of functionalized carbon nanotube/polyacrylonitrile fibers

The plasticized spinning and cyclization behaviors of polyacrylonitrile (PAN) and polyacrylonitrile/functionalized carbon nanotube (PAN/CNT-COOH) composite fibers were studied.

Electrical conductivity and Joule heating of polyacrylonitrile/carbon nanotube composite fibers

Carbon nanotube (CNT) can exhibit electrical conductivity and introduce electric current into polymer. Using dry-jet-wet spin technology, polyacrylonitrile (PAN)/CNT composite fibers with 15 wt% and 20 wt% of CNT content were fabricated. The electrical conductivity of PAN/CNT fibers was enhanced by the annealing process at different temperatures and changed with time. These fibers could also respond to stretching, and the electrical conductivity decreased by 50% when the elongation reached 3%. In addition, electrical current can induce Joule heating effect and thermally transform PAN/CNT composite fibers. With the application of various electrical currents up to 7 mA at a fixed length, conductivity was enhanced from around 25 S/m to higher than 800 S/m, and composite fibers were stabilized in air. The temperature of composite fibers can increase from room temperature to several hundreds of degree Celsius measured by an infra-red (IR) microscope. Joule heating effect can also be estimated according to one-dimensional steady-state heat transfer equation, which reveals the temperature can be high enough to stabilize or carbonize fibers. As a result, this research provides a new idea of heating fabrics for thermal regulation, and a new approach for stabilizing and carbonizing PAN-based carbon fibers.

Controlled functionalization of carbonaceous fibers for asymmetric solid-state micro-supercapacitors with high volumetric energy density.

A 1.8 V asymmetric solid-state flexible micro-supercapacitor is designed with one MnO2 -coated reduced graphene oxide/single-walled carbon nanotube (rGO/SWCNT) composite fiber as positive electrode and one nitrogen-doped rGO/SWCNT fiber as negative electrode, which demonstrates ultrahigh volumetric energy density, comparable to some thin-film lithium batteries, along with high power density, long cycle life, and good flexibility.

Mechanical Properties of Individual Composite Poly(methyl-methacrylate) -Multiwalled Carbon Nanotubes Nanofibers

Multiwalled carbon nanotubes with their superb mechanical properties are an unique filler material for polymer composites. Here, we present an investigation of mechanical properties of electrospun Poly-(methyl-methacrylate) multiwalled carbon nanotubes composite nanofibers. The method of electrospinning was used to fabricate suspended individual Poly-(methyl-methacrylate) multiwalled carbon nanotubes nanofibers. In order to reinforce the nanofibers, different high concentration of multiwalled carbon nanotubes were used. Transmission electron microscopy measurements reveal a successful filling of the nanofibers. The different types of nanofibers were deposited at SiO2 substrates. Which were previously etched, to create trenches for bend tests. Followed by fixing the nanofiber with a focus ion beam platinum deposition at the trench edges. An atomic force microscopy was used to perform the mechanical nanofiber bending tests over trenches. The results were compared with pristine Poly-(methyl- methacrylate) nanofibers to nanofibers with 15 weight% and 20 weight% multiwalled carbon nanotubes composite fibers. We observed that pristine nanofibers have Young's modulus of 136 MPa, while for composite nanofibers with 15 weight% have 2.65 GPa and with 20 weight% have 6.06 GPa (at room temperature and air ambiance). This corresponds to an increase of Young's modulus of 19 fold between the pristine nanofibers and the 15 weight% of mutliwalled carbon nanotubes filled nanofibers. Therefore the increase of the Young's modulus compared between the pristine and the 20 weight% MWCNT filled nanofibers corresponds to 45 fold.

Combined effects of stretching and nanofillers on the crystalline structure and mechanical properties of polypropylene and single-walled carbon nanotube composite fibers

The combined effects of stretching and single-walled carbon nanotubes (SWCNTs) on crystalline structure and mechanical properties were systematically investigated in melt-spun polypropylene (PP) fibers prepared at two different draw ratios. The dispersion, alignment of the SWCNT bundles and interfacial crystalline structure in the composite fibers are significantly influenced by the stretching force during the melt spinning. The nanohybrid shish kebab (NHSK) superstructure where extended PP chains and aligned SWCNT bundle as hybrid shish and PP lamellae as kebab has been successfully obtained in the composite fibers prepared at the high draw ratio and the related formation mechanism is discussed based on the results of morphological observations and 2d-SAXS patterns. Large improvement in tensile strength and modulus has been realized at the high draw ratio due to the enhanced orientation and dispersion of SWCNT bundles as well as the formation of NHSK.

A simple/green process for the preparation of composite carbon nanotube fibers/yarns

We report a simple and green process to prepare poly(vinyl alcohol)/carbon nanotube (PVA/CNT) composite fibers having high mechanical properties.

Effect of fibre spinning conditions on the electrical properties of cellulose and carbon nanotube composite fibres spun using ionic liquid as a benign solvent

The aim of this study was to develop electrically conductive fibres from cellulose. To achieve this, the effect of fibre extrusion speed and fibre winding speed on the degree of alignment of multiwall carbon nanotubes (MWNTs), as well as the resulting electrical properties of the cellulose/MWNTs composite fibres were systematically studied. 1-Ethyl-3- Methylimidazolium Acetate (EMIMAc) was used as an environmentally benign solvent for dissolution of cellulose as well as for dispersion of MWNTs in the solution dope. To achieve good dispersion of MWNTs in the cellulose solution dope, MWNTs were non-covalently functionalized using carboxymethyl cellulose (CMC). This significantly improved the dis- persion of MWNTs in the solution dope. The degree of alignment of MWNTs after both fibre extrusion and winding, was studied using scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). The degree of alignment of MWNTs was correlated with the electrical properties. A significant decrease in electrical conductivity accompanied the increase in degree of alignment of MWNTs when fibres were spun with higher extrusion speed. The decrease was also measured when fibres were spun with higher winding speed using a constant extrusion speed. However, the decrease in conductivity due to winding was low relative to fibres spun at highest extrusion speed.

Super-stretchy lithium-ion battery based on carbon nanotube fiber

Super-stretchy, fiber-shaped lithium-ion batteries with a record strain of 600% are developed by winding two highly aligned carbon nanotube composite fibers. The fiber-shaped battery exhibits high specific capacity, energy density and power density that can be well-maintained under stretching.

Structural Polymer-Based Carbon Nanotube Composite Fibers: Understanding the Processing-Structure-Performance Relationship.

Among the many potential applications of carbon nanotubes (CNT), its usage to strengthen polymers has been paid considerable attention due to the exceptional stiffness, excellent strength, and the low density of CNT. This has provided numerous opportunities for the invention of new material systems for applications requiring high strength and high modulus. Precise control over processing factors, including preserving intact CNT structure, uniform dispersion of CNT within the polymer matrix, effective filler–matrix interfacial interactions, and alignment/orientation of polymer chains/CNT, contribute to the composite fibers’ superior properties. For this reason, fabrication methods play an important role in determining the composite fibers’ microstructure and ultimate mechanical behavior. The current state-of-the-art polymer/CNT high-performance composite fibers, especially in regards to processing–structure–performance, are reviewed in this contribution. Future needs for material by design approaches for processing these nano-composite systems are also discussed.

Synthesis of aligned carbon nanotube composite fibers with high performances by electrochemical deposition

To improve their practical applications, carbon nanotubes (CNTs) have recently been assembled into macroscopic fibers in which the CNTs are aligned to maintain their excellent properties. To further enhance the properties and expand the application of CNT fibers, it is critically important to introduce a second functional phase to produce high performance composite fibers. Herein, a general and efficient electrodeposition method has been developed to synthesize aligned CNT composite fibers into which a wide variety of components including metals and conductive polymers can be incorporated. The resulting composite fibers show remarkable mechanical and electrical properties, which enable promising applications in various fields. As a demonstration, CNT/silver composite fibers exhibit a high signal enhancement under weak laser irradiation when used as wire substrates for surface enhanced Raman scattering, and CNT/polyaniline composite fibers have been used to fabricate wire-shaped supercapacitors which achieve a specific capacitance of 2.26 mF cm−1, at least two orders of magnitude greater than that of bare CNT fibers, and ten times that of other fiber materials, such as plastic wires coated with zinc oxide nanowires.

Study on the Properties of Melt Spinning PAN/MWNTs Composite Fibers

Polyacrylonitrile（PAN）/multi-walled carbon nanotubes (MWNTs) composite fibers were prepared by melt spinning using ionic liquids (ILs) as a plasticizer. The effects of different MWNTs contents on the morphology, mechanical and conductive properties of the composite fibers were discussed. The results showed that property improvements have occurred with the adding of MWNTs. When the content of MWNTs reached 10%, the conductivity of PAN/MWNTs was 8.65×10-3 S/cm.