Buckypaper Research Articles

Preparation, thermal and mechanical properties of poly (ether‐imide) composite reinforced with carbon nanotube buckypaper

ABSTRACTVacuum filtration technique was employed in order to prepare multiwalled carbon nanotube buckypapers (MWCNT‐BP) through a well‐dispersed suspension of MWCNT/H2O with the aid of Triton X‐100 surfactant. The obtained BP (buckypaper) was then infiltrated with a solution of poly (ether‐imide) (PEI) under vacuum conditions. The visual inspection demonstrated the importance of the centrifugation procedure before the vacuum filtration of the suspension, revealing a smooth surface of the as‐prepared buckypaper. Thermogravimetric experiments (TGA) and scanning electron microscopy analyses have demonstrated the role of isopropyl alcohol in the removal of Triton X‐100 from the nanotube network. SEM observations of the cross‐section view of the samples revealed a porous network of the fabricated BP, and an impregnated structure of the PEI/BP composite, suggesting a good interfacial bonding between MWCNT and PEI. Moreover, significant improvements were achieved in mechanical and thermal properties of PEI matrix by the incorporation of BP, as the increase of both the storage modulus (42%) and the T g (11 °C) for the PEI/BP composite. TGA have shown a significant increase in the onset decomposition temperature of the polymer by the incorporation of the BP. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48330.

Carbon nanotube buckypaper and buckypaper/polypropylene composites for high shielding effectiveness and absorption-dominated shielding material

Buckypaper (BP) was prepared as efficient electromagnetic interference (EMI) shielding materials in X-band (8.2–12.4 GHz). The EMI shielding effectiveness (SE) of 31.2 dB and a high specific SE of 19850 dB cm2/g have been realized by BP of 35 μm thick. Notably, the absorption-dominated SE above 100 dB can be achieved by constructing multilayer structure or sandwich structure using BP and polypropylene sheet. For multilayer structure, the increment in EMI SE is contributed by absorption loss and reveals a slow decline trend on the whole with BP layers increasing. For sandwich structure, the improvement in SE is ascribed to the constructive interference, and there is a best polypropylene sheet thickness (0.32–0.48λ, λ = 25 mm) to realize the maximization of SE. In comparison with multilayer structure of the same components of BPs, the SE of sandwich structure with one and two wave-transmitting layers significantly increased by 61.5% and 90% respectively.

A Comparative Study between Knocked-Down Aligned Carbon Nanotubes and Buckypaper-Based Strain Sensors.

Carbon nanotubes (CNTs) are one of the most promising materials in sensing applications due to their electrical and mechanical properties. This paper presents a comparative study between CNT Buckypaper (BP) and aligned CNT-based strain sensors. The Buckypapers were produced by vacuum filtration of commercial CNTs dispersed in two different solvents, N,N-Dimethylformamide (DMF) and ethanol, forming freestanding sheets, which were cut in 10 × 10 mm squares and transferred to polyimide (PI) films. The morphology of the BP was characterized by scanning electron microscopy (SEM). The initial electrical resistivity of the samples was measured, and then relative electrical resistance versus strain measurements were obtained. The results were compared with the knocked-down vertically aligned CNT/PI based sensors previously reported. Although both types of sensors were sensitive to strain, the aligned CNT/PI samples had better mechanical performance and the advantage of inferring strain direction due to their electrical resistivity anisotropic behavior.

Improved static and dynamic mechanical properties of multiscale bucky paper interleaved Kevlar fiber composites

Herein, the influence of bucky paper interleaves and dispersed MWCNT network on static and dynamic mechanical properties of Kevlar-epoxy composites, subjected to different loading conditions is investigated. Multiscale hybrid laminar Kevlar composites are prepared by vacuum impregnation followed by compression moulding technique. Subsequently, these hybrid composites are subjected to tensile, flexural, dynamic mechanical and low velocity impact and directly compared with basic Kevlar composite (KE) laminate. It is found that bucky paper interleaves along with dispersed MWCNT (KEBC) improve interlaminar and interfacial properties respectively. It is found that the maximum dynamic impact energy absorption and load carrying capacity of KEBC increase to 13.8 J and 2650 N respectively which shows an overall improvement of 31% over KE. These results are further confirmed by Charpy's impact test, in which maximum impact toughness reaches to 90.4 J/mm2, which is consistent with dynamic impact test results. After conducting various lab scale mechanical tests, ballistic test is also performed over KEBC and KE. It is found that, in case of KEBC, back face signature is reduced to 30% over KE, which confirms the collective effort of bucky paper interleaves and dispersed MWCNT in enhancing the energy absorption capability of hybrid laminar composite.

Escherichia Coli Fed Paper-Based Microfluidic Microbial Fuel Cell With MWCNT Composed Bucky Paper Bioelectrodes.

This paper demonstrates a simple-in-struct- ure, cost-effective, and environment-friendly Microfluidic Paper-based Analytical Device for Microbial Biofuel Cell ( μ PAD-MBFC). It consists of a microchannel with biofuel cell (Escherichia.Coli) and an oxidant (aerated tap water) flowing co-parallelly over Multiwalled Carbon Nanotube (MWCNT)-based Bucky Paper (BP) electrodes using a self-capillary and co-laminar flow mechanism. The electrochemical studies, such as open circuit potential (OCP) and polarization were evaluated using a potentiostat. Various volumetric bacterial studies were also carried out to find out the best suitable optimal bacterial volume. Subsequently, the morphological and detailed element composition study of electrode surface was performed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. This well-designed portable μ PAD-MBFC yields a maximum power density of 4 [Formula: see text]/cm2 ( [Formula: see text]/cm2) at 0.405 V over [Formula: see text] of culture and leveraging to its long-lasting potential to operate miniaturized microelectronics sensors and portable devices.

Buckypaper-Bilirubin Oxidase Biointerface for Electrocatalytic Applications: Buckypaper Thickness.

Electrode materials play an important role on the electrocatalytic properties of immobilized biocatalysts. In this regard, achieving direct electronic communication between the electrode and redox sites of biocatalysts eliminates the need for additional electron transfer mediators for biocatalytic applications in fuel cells and other electrochemical energy devices. In order to increase electrocatalytic currents and power in fuel cells and metal-air batteries, conductive carbon-nanostructure-modified large surface area electrodes are quite useful. Among various electrode materials, freestanding buckypapers made from carbon nanotubes have gained significance as they do not require a solid support material and thus facilitate miniaturization. In this article, we present the effect of buckypaper (BP) thickness on the electrocatalytic properties of a bilirubin oxidase (BOD) enzyme. In this study, we prepared BPs of varying thicknesses ranging from 87 μm, the minimum thickness for suitable handling with a good stability in aqueous experiments, to 380 μm. BOD was adsorbed overnight onto the BPs, mostly via hydrophobic and π-π interactions since the nanotubes used were not chemically functionalized. Furthermore, intercalation of the BOD molecules onto the nanotubes' multicylindrical network is feasible. We determined that the lower range BP thickness (<220 μm) exhibited better sigmoidal shaped electrocatalytic currents than the higher BP-thickness-based BOD biofilms with larger capacitive currents. An oxygen reduction current density of up to 3 mA cm-2 is achieved without the use of any redox mediators or tedious electrode modifications. Using the 87 μm thick BP as the representative case, we were able to obtain distinguishable peaks for all Cu sites of BOD and assign their types, T1, T2, and T3, based on the peak-width at half-maximum in anaerobic cyclic voltammograms. Our peak assignment is further supported by the appearance of dual electrocatalytic oxygen reduction waves at a higher scan rate region (>10 mV s-1) in oxygen-saturated buffer, which is identified to be driven by an ∼3.5 times faster electron transfer rate from the buckypaper to the T2/T3 center than the T1 Cu site. Findings from this study are significant for designing enzyme electrocatalytic systems and biosensors in general and fuel cells and aerobic energy storage devices in particular, where the cathodic oxygen reduction current is often inadequate.

Improved strain sensing capability of nano-carbon free-standing buckypapers based strain gauges

Nano-carbons including carbon nanotubes (CNTs) and graphite nanoplatelets (GNPs) have been proved to have good strain sensing capability, but they are often made together with flexible substrates, which may limit their multifunctional applications such as internal sensors. In this study, free-standing CNT/GNP buckypapers (BPs) with various weight ratios were prepared by filtrating their suspensions. Relative resistance variation depending on tensile strain of the obtained BPs was examined to evaluate their strain sensing capability, e.g. gauge factor (GF) and linearity (r2) within the whole testing strain range. Results show that enhanced strain sensing capability of the hybrid BPs is obtained, with a maximum GF of 8.18, and r2 of 0.999, respectively, in a relatively large strain range from 0% to 2%, when the GNP loading reaches 50 wt%. Moreover, in situ strain sensing capability of the hybrid BPs was practically monitored by sticking them onto the surfaces of epoxy resin. As expected, the hybrid BPs exhibit a relatively high in situ GF of 10.83 and r2 of 0.987, as well as excellent repeatability and stability. Excellent strain sensing capability of the free-standing BPs reveal that they have potential applications in the fields of internal and external strain or damage monitoring.

Preparation and transport properties of oriented buckypapers with single walled carbon nanotubes

Buckypapers (BPs) with carbon nanotubes (CNTs) are very promising for a lot of applications, in which their high conductance, strength and small weight are required. In this work, isotropic BPs were prepared using the solution-based deposition that includes the single walled carbon nanotubes (SWCNTs) dispersion and the dispersion filtration from a solvent. To increase the BP conductivity, the orientation of the SWCNT bundles composing BPs and a following iodine doping were applied. The method of extrusion through the narrow (300 µm) gap was used for the SWCNT orientation. The temperature dependences of conductance for isotropic, oriented and doped BPs were studied to understand the effect of CNT alignment and the mechanism of transport through SWCNT BPs. It was shown that bundle orientation increases the BP conductivity from ~103 S × cm-1 to ~104 S × cm-1, and iodine doping of oriented samples additionally increase the conductivity by an order. The fluctuation – assisted tunneling between CNT bundles was used to describe the mechanism of low temperature conductivity.

M3D aerosol jet printed buckypaper multifunctional sensors for composite structural health monitoring

Abstract Sensors placed along various stages of manufacturing processes can identify errors and ensure the quality of a product. Specially, sensors are becoming essential for more complicated composite fabrication due to coupling together heat transport, curing kinetics, resin rheology and flow as well as pressure effects. In this research, embedded composite sensor fabrication, maskless mesoscale materials deposition system has been used to print electrically conductive silver patterns on the carbon nanotube (CNT) sheets or buckypaper (BP) to measure its resistance change, and thus used as embedded sensors in composite laminates for both manufacturing process and structure health monitoring. Three different samples of nanotube sheets were used in this work and compared. The samples exhibited slightly different behaviors in terms of resistive response during the resin infusion and curing process with vacuum bagging, yet also demonstrated similar patterns, which indicated their sensing capabilities. Upon the resin flow, the sensor resistance dropped ∼20–30% from the initial value, then increased up to 120–145% compared to its minimum value at the final curing stage. After curing process, embedded sensors could monitor the impact or structural deformation of a composite part.

Fabrication of flower-like TiO2 on Bucky paper with enhanced photocatalytic activity

The difficulty of recycling and low photocatalytic efficiency in the visible light significantly limit the use of nano-TiO2 in water pollution control. In this work, Bucky papers (BPs), which play a vital role for adsorption of pollutants and transfer of electrons, are introduced as substrates to fabricate and anchor TiO2 nanorods by a facile hydrothermal method. The photocatalytic properties of the TiO2 and BP composites (TiO2@BP) are studied by photodegrading methylene blue in water solutions. It is found that TiO2@BP possesses four times photocatalytic efficiency for methylene blue of TiO2@Si under ultraviolet light irradiation and 10 times under visible light irradiation. This is considered to be attributed to the synergic effect of TiO2@BP system and surface defects of TiO2 nanorods. The TiO2@BP also shows a stable photocatalytic property even after five cyclic photocatalytic degradation. This study indicates that TiO2@BP is a promising candidate for photocatalytic applications, which provides a reference for further research on synthesis of reusable photocatalysts with higher efficiency.

Optimization of Triton X-100 removal and ultrasound probe parameters in the preparation of multiwalled carbon nanotube buckypaper

A highly porous film composed of a three-dimensional network of multi-walled carbon nanotube (MWCNT), also known as buckypaper (BP), was prepared by vacuum filtration of a well-dispersed suspension of MWCNT/H20 with the aid Triton X-100 surfactant. The key contribution of this work is to achieve the best parameters during the preparation of the suspension and find the best way to remove the excess triton X-100 from the nanotube network. The stability of suspension in different pH, the adsorption capacity, and the reusability of MWCNT was also evaluated. The effects of ultrasound parameters on the BP properties were systematically investigated and characterized by Raman Spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and electric resistivity using a four-point probe technique. In addition, the results of using different solvents to wash the BP after filtration process were analyzed by Thermogravimetric analyses (TGA), Fourier transform infrared spectroscopy (FT-IR), and Field emission gun scanning electron microscopy (FEG-SEM). The optimum condition employed in this work (25 min–40%) exhibited the ID/IG ratio of 2.17 and L002 of 5.597 nm, which suggests less damage to MWCNT. This study confirms that MWCNT-BP can be used to fabricate high-loading CNT/polymer composites with improved electrical properties.

Effect of Pore Size on the Ion Electrosorption and Hydrogen/Deuterium Electrosorption Using Sodium Chloride in H2O and D2O

In nanoconfinement, the reversible electrochemisorption of hydrogen extends the voltage window of aqueous electrolytes. This process has been well studied for different aqueous electrolytes but not compared to the performance of heavy water. Herein, we study hydrogen and deuterium electrosorption on a porous carbon electrode under negative polarization using sodium chloride as the salt. As electrodes, we use microporous carbons with an average pore size in the sub-nanometer range and, for comparison, mesoporous carbon nanotube bucky paper. We show that the hydrogen electrochemisorption and gas evolution processes are more pronounced than for deuterium while the same potential is applied. Our data confirm lower ion mobility of D2O compared to H2O, and a shift of the reversible charging and discharging process toward more negative potentials.

High‐performance thermoplastic hybrid composite reinforced with bucky paper for electromagnetic interference shielding

Multiwalled carbon nanotubes (MWCNTs) have extraordinary electrical conductivity but limited applications due to the ease of agglomeration, especially in thermoplastic composite. With the aim of achieving high electromagnetic interference shielding performance by applying MWCNTs in thermoplastic matrix, MWCNTs were made into buckypaper (BP) and then hot pressed with PP/PLA/TiO2 hybrid films, forming sandwich‐structured BP/PP‐PLA‐TiO2 hybrid composite films. BP was examined in terms of morphology, cell structure, and electrical conductivity, while BP/PP‐PLA‐TiO2 hybrid composite film was tested for electromagnetic shielding effectiveness (EMSE), thermal properties and UV‐cut efficacy. It was found that using vacuum filtration successfully produced BP with a smooth and sleek surface and an even porosity ranging between 20 and 45 nm. The electrical conductivity of BP was proportional to its thickness. About 90 μm‐thick BP had 75.62% lower surface resistivity and 36.63% higher electrical conductivity than 30 μm‐thick BP. Moreover, the EMSE of BP/PP‐PLA‐TiO2 composite film increased as a result of the higher thickness of BP. When the thickness of BPs was 90 μm, the BP/PP‐PLA‐TiO2 composite film had an average EMSE of 40 dB at 0–3 GHz and a peak of 70 dB, and 119% higher tensile strength and 11% higher elastic modulus than those of PP/PLA/TiO2 composite film. BP/PP‐PLA‐TiO2 composite film had UV‐cut efficacy that was close to 0%. The addition of BP was proven to improve the crystallization and thermal stability. POLYM. COMPOS., 40:3065–3074, 2019. © 2018 Society of Plastics Engineers

Rotating-disc micro-solid phase extraction of F2-isoprostanes from maternal and cord plasma by using oxidized buckypaper as sorbent membrane

This paper describes the development of an original micro-solid phase extraction device and its evaluation for the isolation of F2-isoprostanes (F2-IsoPs) from cord and maternal plasma samples. The unit is very simple and consists in a rotating disc (1.8 cm diameter) of oxidized buckypaper (BP), enwrapped in a polypropylene mesh pouch. Even if the selected F2-IsoPs have logP and pKa values that make them suitable candidates for their sorption on BP, several parameters were optimized to maximize recoveries: time of adsorption and desorption; stirring speed; volume, pH and ionic strength of the sample; type, volume, and fractions of the elution solvent; oxidation grade of BP. Among all, the last one was crucial in affecting extraction yields because of the analyte interactions with polar functionalities, introduced by a preliminary oxidative acid treatment. The investigation established the optimal oxidation time and highlighted the pros and cons of the acid activation step. All extracts were analyzed by means of liquid chromatography-tandem mass spectrometry (LC–MS/MS). Validation was performed according to the main FDA guidelines for bioanalytical methods. Depending on the spike level and analyte, recoveries ranged between 30 and 120% with precision and accuracy values lower than 20%. Quantitative analysis was accomplished by matrix-matched calibration curves whose determination coefficients were higher than 0.95. Lower limit of quantitation (LLOQ) spanned the range 2.45–6.77 μg L−1. The validated method was applied to the analysis of eight pairs of mother/child plasma samples, revealing the presence of 8-iso-15-keto-PGF2α and 8-iso-PGE2 at a concentration of about 10 μg L−1 in most cord plasma samples of preterm newborns.

Modelling and Analysis of SUKHOI FGFA and Introduction of composite materials to SUKHOI FGFA

This paper talks about the modal and flow analysis done on the aircraft with composite materials. We are using steel, carbon fibre and Bucky paper. This will give a brief description and contrast between the three composite materials on sukhoi fgfa. Carbon fibre reinforced composites (CFRPs) are light weight, have high strength and modulus, which make them qualified candidates for numerous automotive and aerospace industries. However one of the major technical challenges for these materials in airplane structures, in terms of aircraft safety and durability, is lightning strike protection (LSP).This is due to the inadequate electrical properties of normal CFRPs. Although, CFRPs have relatively good in-plane electrical conductivity compared to neat epoxy resin, they lack metal-like high conductivity for LSP applications. To solve this issue, metal materials such as copper or aluminium mesh are attached to carbon fibre composites in the aircraft structure. This solution is not satisfactory due to heavy weight of metals and the occurrence of galvanic corrosion between metals and CFRPs. On other hand carbon nano tubes (CNTs) possess great potential for enhancing high-performance and multifunctional properties of composites and exhibit incredible mechanical, electrical and thermal properties, which can replace the metal mesh materials.

Interleaved MWCNT buckypaper between CFRP laminates to improve through-thickness electrical conductivity and reducing lightning strike damage

With the recent development in fabrication of various electrically conductive composites using various conductive fillers, there is a new trend among researchers to realize electrically conductive carbon fiber reinforced composite (CFRP) for lightning strike protection. Traditional epoxy-based CFRP does not provide enough electrically conductive paths to the incident lightning current for the fast dissipation, leading to evaporation of resin and fiber damage around lightning attachment zone. In this work, multiwall carbon nanotube (MWCNT) buckypaper (BP) are interleaved between CFRP laminates to replace the resin rich area with epoxy impregnated BP. This interleaved BP not only effectively enhanced the in-plane and through-thickness electrical conductivity of the CFRP laminate but also improved resistance against lightning strikes. Electrical conductivity is improved by 697% and 643% in in-plane and through-thickness direction respectively. SEM confirmed the proper impregnation of BP and good interphase between carbon fiber and BP layers. Simulated lightning test of 40 kA is conducted on pristine and BP-interleaved composites. Improved electrical conductivity in BP composite proved to be highly effective against lightning strike confirmed by the residual mechanical test.

Synthesis of polyvinyl alcohol (PVA) infiltrated MWCNTs buckypaper for strain sensing application

Buckypaper (BP)/polymer composites are viewed as a viable option to improve the strain transfer across the buckypaper strain sensor by means of providing better interfacial bonding between the polymer and carbon nanotubes (CNTs). Multiwall carbon nanotubes (MWCNTs) BP/polyvinyl alcohol (PVA) composites were fabricated by a sequence of vacuum filtration and polymer intercalation technique. The optimized conditions for achieving a uniform and stable dispersion of MWCNTs were found to be using ethanol as a dispersion medium, 54 μm ultrasonic amplitude and 40 min sonication time. FTIR analysis and SEM spectra further confirmed the introduction of oxygenated groups (-COOH) on the surface of MWCNTs BP and the complete infiltration of PVA into the porous MWCNTs network. At MWCNTs content of 65 wt. %, the tensile strength, Young’s modulus and elongation-at-break of PVA-infiltrated MWCNTs BP achieved a maximum value of 156.28 MPa, 4.02 GPa and 5.85%, improved by 189%, 443% and 166% respectively, as compared to the MWCNTs BP. Electrical characterization performed using both two-point probe method and Hall effect measurement showed that BP/PVA composites exhibited reduced electrical conductivity. From the electromechanical characterization, the BP/PVA composites showed improved sensitivity with a gauge factor of about 1.89–2.92. The cyclic uniaxial tensile test validated the high reproducibility and hysteresis-free operation of 65-BP/PVA composite under 3 loading-unloading cycles. Characterization results confirmed that the flexible BP/PVA composite (65 wt. %) with improved mechanical and electromechanical properties is suitable for strain sensing applications in structural health monitoring and wearable technology, as an alternative choice to the fragile nature of conventional metallic strain sensors.

Self-heating and deicing epoxy/glass fiber based carbon nanotubes buckypaper composite

The recent developments in the aeronautical structure industry have seen a sharp rise in the use of polymer composite materials. The performances of all aerodynamic surfaces are heavily dependent on the shape and the surface form. The modification of these surfaces due to condensation and melting of ice can cause catastrophic decreases in the aerodynamic performance. In this study polymer composite materials as heater were made and studied. The feasibility of using advanced polymer composites for de-icing application was validated and studied through experiments. It consists of thin carbon nanotubes (CNTs) Bucky paper placed between two glass fibers veils and then infiltrated with an epoxy polymer resin and cured. The composite can be heated up very quickly using an electrical power source. The idea of using this new material as a heater and de-icing material was explored experimentally. For that purpose, the temperature distribution was monitored at different positions of the panel using thermal imaging. Experimental results show that the surface temperature of the panel increases gradually as the heating time increases. This temperature increased in a short time period of heating time, implying that the composite panels with CNTs Bucky paper display an excellent heating performance.

Electromagnetic interference shielding properties of graphene/MWCNT hybrid buckypaper

A type of lightweight and flexible graphene/multi-walled carbon nanotube (MWCNT) hybrid buckypaper (BP) is fabricated, which show superior shielding effectiveness (SE) of electromagnetic interference and without polymer. The EMI SE of graphene/MWCNT hybrid BP with thickness of 130 μm is up to ∼51 dB at 8 GHz, which is much higher than that of pure MWCNT BP with same thickness (∼32.5 dB) and the best electrical conductivity is up to 10,000 S/m. More important, the improvement in EMI SE is contributed to the SE absorption, while the SE reflection is almost unchanged. This paper-like material is smooth, tough, and flexible enough to be attached on the complex curved surface structure. A facile way to fully develop graphene and MWCNT in lightweight and flexible EMI shielding materials and devices is provided here.

In situ self-sensing of delamination initiation and growth in multi-directional laminates using carbon nanotube interleaves

Self-sensing capability of carbon nanotube buckypapers (BPs), played as in situ sensor on delamination damage in multi-directional laminates, was investigated in this paper. BPs were interleaved into these interfaces of the laminates, where delamination tends to happen firstly under tensile loading. The inserted BPs are porous and conductive, which can benefit infiltration of epoxy resin and give contribution to damage monitoring. Systematic analysis of resistance variation (ΔR/R0%) against strain has demonstrated that BPs are sensitive to the initiation and growth of delamination. When delamination initiates, a sudden rise of the ΔR/R0% or the slope of the ΔR/R0%-strain curves is observed and corresponding delamination initiation stresses are simultaneously obtained. Moreover, effect of thicker laminates on the sensitivity is also examined and the self-sensing ability of BPs has been further proved. Finally, tensile properties of the BPs interleaved laminates slightly change compared with these of base laminates.