Multi-walled Carbon Nanotube Composites Research Articles

Dual-Nozzle Extrusion Printing of Highly Sensitive and Durable Strain Sensor Based on MWCNT/Ecoflex Composites

Flexible strain sensors have made great progress and been applied tentatively in recent years. However, there are still many challenges and problems hindering their widespread application, including incompatible high sensitivity and wide detection range, poor durability, and time-consuming fabrication procedures. In this work, a dual-nozzle-assisted one-step strategy for the fabrication of integrated flexible strain sensors is proposed. During the fabrication, Ecoflex and its composite multi-walled carbon nanotube (MWCNT)/Ecoflex were extruded and thermally cured from the two nozzles, respectively. Taking advantage of the same base resin, the strain-sensitive and the insulating components in the fabricated flexible strain sensors are chemically bonded firmly and form an integrated device. The fabricated sensor exhibits good performance in terms of high gauge factor (GF = 165.3), good stability, low hysteresis, fast response time (60 ms), wide detection range (0%–300% strain), and ultralow detection limit (0.1% strain), showing promising applications in health monitoring and human–computer interaction.

Machine Learning for Design of Phosphorene Nanozyme Sensor and Its Intelligent Analysis of Clenbuterol in Animal-Derived Agro-Products

Extraordinary electronic performance and unique structural characteristic of black phosphorene (BP) often is used as electrode modified materials in electrochemical sensors. In this paper, a machine learning (ML) strategy for phosphorene nanozyme sensor and its the intelligent of clenbuterol (CLB) in pork and pig serum samples is prepared. The silver nanoparticles decorate BP to prevent oxidative degradation of BP surface and further hybridize with multi-walled carbon nanotubes (MWCNTs) composites containing nafion (Nf) treated with isopropanol (IP) to improve environmental stability and electrocatalytic capacity of BP. Back-propagation artificial neural network (BP-ANN) model combined with genetic algorithm (GA) is employed to optimize sensor parameters such as BP concentrations, MWCNTs concentrations and ratio of VNf:VIP, and compared with orthogonal experimental design (OED). Least square support vector machine, radial basis function and extreme learning machine are implemented to establish quantitative analysis model for CLB. The results showed that the CLB response current of BP sensor by BP-ANN-GA was improved 9.02% over OED method. Compared with the traditional linear regression, three models displayed better predictive performance, and LS-SVM was the best with the R 2 , RMSE and MAE and RPD of 0.9977, 0.0303, 0.0225, and 18.74, respectively. The average recoveries of CLB in pork and pig serum was 98.66% ∼ 101.67%, and its relative standard deviations was 0.19% ∼ 0.84%, indicating that electrochemical sensor using machine learning for intelligent analysis of CLB in animal-derived agro-products products was both feasible and practical.

MWCNT Filled Banana-Rice Husk Epoxy Hybrid Natural Fiber Polymer Composites

Natural fiber composites are prepared by combining two varying fiber/filler contents with a single matrix material. Hybrid polymer composite material made with synthetic agents (Thermosetting polymer) and natural fiber/filler contents. The current study focuses on hybrid polymer composite Multi Walled Carbon nanotubes (MWCNT)-filled Banana fiber/Rice husk filler-reinforced composites that have been assessed for mechanical responses. The banana fiber mat has been in the constant piling mode and altering the MWCNT and rice husk percentage in volume. Vacuum lay-up technique was used to construct the hybrid polymer composite and MWCNT was included with the help of ultrasonic probe sonicator instrument. Mechanical testing is performed accordance to the ASTM standards. The integration of MWCNT, as well as the constant piling order of banana fiber layers, has a stronger impact on mechanical properties. The three samples are prepared at the extremities 5% Banana fiber mat uniform loading and rice husk proportions are 10%, and 15% along with MWCNT filler (0.5% and 1%) for BRME2 and BRME3. The exhibited mechanical testing of the hybrid polymer composite to identify the conventional enhancement of hardness, tensile, impact, flexural, and compressive properties. Scanning Electron Microscope (SEM) is used to examine the fractograph of the tensile sample prepared with BRME3. BRME2 polymer composite with 1% weight of MWCNT was identified higher mechanical properties compare to BRME3 and BRME1 (Tensile, Flexural Strength, and Shore-D Hardness: 46.5 MPa, 59.7 MPa, and 88.5). Furthermore, the impact strength of BRME3 was significantly higher than BRME2 and BRME1.

Glucose Biosensor Based on Glucose Oxidase Immobilized on BSA Cross-Linked Nanocomposite Modified Glassy Carbon Electrode

Glucose sensors based blood glucose detection are of great significance for the diagnosis and treatment of diabetes because diabetes has aroused wide concern in the world. In this study, bovine serum albumin (BSA) was used to cross-link glucose oxidase (GOD) on a glassy carbon electrode (GCE) modified by a composite of hydroxy fullerene (HFs) and multi-walled carbon nanotubes (MWCNTs) and protected with a glutaraldehyde (GLA)/Nafion (NF) composite membrane to prepare a novel glucose biosensor. The modified materials were analyzed by UV-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), and cyclic voltammetry (CV). The prepared MWCNTs-HFs composite has excellent conductivity, the addition of BSA regulates MWCNTs-HFs hydrophobicity and biocompatibility, and better immobilizes GOD on MWCNTs-HFs. MWCNTs-BSA-HFs plays a synergistic role in the electrochemical response to glucose. The biosensor shows high sensitivity (167 μA·mM-1·cm-2), wide calibration range (0.01-3.5 mM), and low detection limit (17 μM). The apparent Michaelis-Menten constant Kmapp is 119 μM. Additionally, the proposed biosensor has good selectivity and excellent storage stability (120 days). The practicability of the biosensor was evaluated in real plasma samples, and the recovery rate was satisfactory.

Synthesis, characterization and structure of novel Vanadium (III) complexes: Investigation of electrochemical application

From the prospective of possible electrochemical application of vanadium complexes, here, we report the two novel vanadium complexes. Namely, Tp*VO(3,5-Me2pzH)2(CH3CN) (1) (where, Tp* = hydro tris(3,5-dimethylpyrazolyl)borate and Tp*VTp*(2) these complexes were prepared in a good yield starting from V(III) chloride and hydro tris (3, 5 dimethyl pyrazolyl) borate. Both the complexes were characterized by NMR, Mass, and FTIR spectroscopy. In addition, cyclic voltammetry is used to investigate electrochemical processes of 1 and 2. The electrochemical active species exhibits two noteworthy redox peaks and exhibits considerable catalytic action towards glassy carbon electrodes with a composite of multi-walled carbon nanotubes (MWCNTs). Moreover, the complex1/MWCNTs/GC electrode detects the H2O2 in PBS (pH 7) electrolyte solution by cyclic voltametry (CA), differential pulse voltametry (DPV) and chronoamperometry (CA) techniques; Under the optimal conditions, the reduction peak current is linear to the H2O2 concentration in the ranges, detection limit for; CA: 50–500 μmol; 4.5 μmol L−1, CV: 50–400 μmol; 9.5 μmol L−1, DPV: 50–500 μmol; 8.3 μmol L−1. Single-crystal XRD analysis revealed that complex 1 crystallized in the orthorhombic space group P212121with lattice parameters a = 11.960(4) Å, b = 12.571(4) Å, c = 20.465(7)Å, Z = 4. In addition, distorted octahedral geometry was observed around the vanadium metal centre. Surface morphology of the complexes was probed by scanning electron microscopy (SEM).

Magnetic properties of Ni-coated fibers in a polymer matrix for electro-magnetic interference shielding applications

Electromagnetic interference shielding composite materials can be designed with properties that are tailored for specific applications. We have explored the magnetic properties of Ni-coated carbon fibers embedded in a polymer matrix through an extrusion process. This method can produce large, pliable flat sheets, which can be easily bent and shaped. Microscopy imaging shows that the extrusion process preferentially orders most of the fibers with their long axis along the extrusion direction. The measured samples reached 90% of the saturation magnetization value at a field of approximately 800 Oe along the extrusion direction, much lower than needed for other directions (in-plane perpendicular to the extrusion or perpendicular to the foil surface). A field on the order of 6 kOe must be applied to obtain the full saturation of the magnetization in all three directions. The absorption characteristics were measured, with zero external applied field to determine the shielding effectiveness of the composite materials for multiple orientations with respect to the TE10 mode of an S-band waveguide. The nickel-coated carbon fiber composite materials exhibit dramatic orientation-dependent shielding effectiveness. The most effective orientation has shielding effectiveness of up to 45 dB at 4.5 GHz, which is comparable to multi-walled carbon nanotube composites with similar volumetric filling fractions.

Multilayered Composites with Carbon Nanotubes for Electromagnetic Shielding Application.

Bulk polylactic acid (PLA)/multiwall carbon nanotube (MWCNT) composites were prepared and investigated in wide frequency ranges (20 Hz-1 MHz and 24-40 GHz). It was determined that the percolation threshold in bulk PLA/MWCNT composites is close to 0.2 vol.% MWCNT. However, the best microwave dielectric properties and absorption were observed in composites with 3.0-5.0 vol.% MWCNT. Therefore, for future investigations, we selected layered (laminate) polymeric structures with gradual changes in MWCNT concentration from 0.2 to 8.0 vol.% MWCNT. Two approaches to laminate structure designs were examined and compared: a five-layer composite and a nine-layer composite that included four pure PLA middle layers. The addition of MWCNT enhanced the elastic modulus by up to 1.4-fold and tensile strength by up to 1.2-fold, with the best performance achieved at 5.0 vol.% loading. High microwave shielding was observed for these layered PLA/MWCNT structures with a gradient change in MWCNT concentration (up to 26 dB in both transmission and absorption coefficients) in the broad frequency range (from 24 to 40 GHz). Obtained structures are highly anisotropic, and the absorption coefficient is 2-5 dB higher in the direction of MWCNT concentration increase; however, the transmission coefficient is the same in both directions. The properties of microwave absorption are mainly unaffected by the additional polymeric layers. The absorption of the layered structure is greater than the absorption of single-layer composites with an optimal MWCNT concentration of the same thickness. The proposed laminate structure design is promising in the field of efficient electromagnetic shielding.

Modification effects of multi-walled carbon nanotubes on the mechanical and rheological properties of epoxy asphalt

Epoxy asphalt (EA) was widely used in road engineering fields, but previous research found that there were compatibility problems between epoxy (EP) and asphalt. In practical engineering applications, the compatibility of EA was improved by adding complex auxiliary agents. Although the composite of multi-walled carbon nanotubes (MWCNTs) and epoxy could improve the adhesion, corrosion resistance, and toughness of asphalt, it was difficult to achieve an excellent modification effect because of the agglomeration of MWCNTs. To improve the composite effect of epoxy and MWCNTs, carboxyl functional groups were added to MWCNTs under mixed acid conditions to reduce the agglomeration and achieve a better combination with epoxy. Then, MWCNTs/EP was prepared under physical stirring conditions. The MWCNTs/EP was observed by scanning electron microscopy (SEM), and it was found that MWCNTs could be uniformly dispersed in epoxy. To research the modification effect of MWCNTs on mechanical and rheological properties of EA, a variety of MWCNTs/EA with different proportions were prepared. The impact of different mixing ratios of MWCNTs/EP on the mechanical and rheological properties of asphalt was evaluated by dynamic shear rheological (DSR) experiments. The results showed that the addition of the appropriate amount of MWCNTs could further improve the high-temperature stability of EA. In this case, MWCNTs played a positive role in the modification of epoxy. However, the improper introduction of MWCNTs would have a negative weakening effect, which would weaken the high-temperature performance of EA. Through comparison, the optimal mixing ratios of MWCNTs and epoxy were finally determined as 6 % EP + 1.4 % MWCNTs and 20 % EP + 0.125 % MWCNTs.

High-performance thermoplastic polyaryletherketone/carbon fiber composites: Comparison of plasma, carbon nanotubes/graphene nano-anchoring, surface oxidation techniques for enhanced interface adhesion and properties

This investigation highlights the development and performance comparison of carbon fiber (CF)-polyaryletherketone (PAEK) thermoplastic laminates prepared using CF, surface-modified with plasma, multi-walled carbon nanotubes (MWCNT), graphene, acid, and rare earth elements. Analysis of surface-treated CF by Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) revealed development of functional groups and changes in elemental composition on the CF surface. Significant lowering of contact angle and improvement in wettability was achieved by plasma and MWCNT/graphene treatment on CF. Field emission scanning electron microscopy (FESEM) analysis gave insight into the surface irregularities caused by various surface treatment techniques. The CF-PAEK composites were prepared by film stacking and compression moulding. The plasma-treated PAEK-CF composites exhibited the highest tensile properties, flexural strength, fracture toughness, and interlaminar shear strength. The superior properties are credited to better interfacial adhesion between CF and PAEK arising from mechanical interlocking over the roughened surface and covalent bonds by functional groups grafted on CF surface by plasma. MWCNT and graphene-anchored CF-PAEK composites also showed significant improvement in mechanical properties attributed to the bridging effect and interfacial interaction arising from increased surface area and functional groups. The surface-treated CF-PAEK composites exhibited a positive shift in the glass transition temperature, which is evidence of better adhesion. In dynamic loading conditions, MWCNT anchored CF-PAEK composite presented the highest storage modulus and energy absorption characteristics. Examination of the tensile fracture surface and fiber pull-out gave insight into the failure pattern and interfacial adhesion mechanism for the individual surface modification techniques.

Electrochemical, Ultrasensitive, and Selective Detection of Nitrite and H2O2: Novel Macrostructured Phthalocyanine with Composite MWCNTs on a Modified GCE.

In the current study, the synthesis of tetra-4-(2-methoxyphenoxy) carboxamide cobalt(II) amide-bridged phthalocyanine (CoTMePhCAPc) is described, as well as its characterization by Fourier transform infrared (FT-IR), UV-visible, and mass spectroscopy; powder X-ray diffraction (PXRD); thermogravimetric analysis (TGA); scanning electron microscopy (SEM); and electrochemistry. Sensing of nitrite (NO2-) and hydrogen peroxide (H2O2) simultaneously was done on CoTMePhCAPc with the composite multiwalled carbon nanotube (MWCNT)-modified glassy carbon electrode (CoTMePhCAPc/MWCNT/GCE) in the range of linear absorption (NO2- and H2O2: CV 50-750, differential pulse voltammetry (DPV) 50-750, CA 50-500 nmol L-1), lower detection limit (NO2- and H2O2: CV 10.5 and 12.5, DPV 10.5 and 11.2, CA 6.0 and 5.5 nmol L-1), and sensitivity (NO2- and H2O2: CV 0.379 and 0.529, DPV 0.043 and 0.049, CA 0.033 and 0.040 μA nM-1 cm-2). The composite electrode exhibits improved electrocatalytic behavior compared to modified electrodes for nitrite and H2O2. The CoTMePhCAPc/MWCNT/GCE sensor displays good selectivity even in the presence of an excess of interfering metal ions and biomolecules at the applied potentials of +400 mV (nitrite) and -400 mV (H2O2). Moreover, the fabricated sensor was studied with various phosphate-buffered saline (PBS) (pH 5-9) electrolyte solutions. The unknown H2O2 concentration in blood samples and apple juice and nitrite concentration in drinking water and butter leaf lettuce were all measured using the usual addition method. Docking analysis clearly indicates that the ligand shows excellent inhibition activity toward the three subjected protein molecules.

A study on development of silicone rubber with conductive carbon, polyaniline, MWCNT composite for EMI shielding

The multiwall carbon nanotubes (MWCNTs) were grown by CVD method and using Ni impregnated zeolite as a substrate. The prepared MWCNT diameter varied from 10 to 60 nm and length in few microns. The silicone rubber (SR) was mixed well with conductive carbon, Polyaniline (PANI) and MWCNTs in two roll mill. The prepared silicone rubber materials were fabricated in the form of sheets with dimensions of 200 mm × 200 mm × 2 mm by using compression molding technique. The prepared sheets were subjected for EMI shielding efficiency measurements at low frequency (< 1.5 GHz) and high frequency range from 1 GHz to 18 GHz. At high frequency the shielding effectiveness of the Conducting Silicone Rubber and Conductive silicone rubber with MWCNT was found to be 24 dB and 48 dB. The volume resistivity measurements were also carried for all the prepared silicone rubber sheets, the results reveals that SR + MWCNT, CSR + MWCNT composites shows volume resistivity 4032 and 20.7 Ω.cm respectively. This confirms the conductivity of CSR + MWCNT is enough to exhibit good Shielding Effectiveness.

Nanocomposite Electrode of Titanium Dioxide Nanoribbons and Multiwalled Carbon Nanotubes for Energy Storage.

TiO2 is one of the most investigated materials due to its abundance, lack of toxicity, high faradaic capacitance, and high chemical and physical stability; however, its potential use in energy storage devices is constrained by its high internal resistance and weak van der Waals interaction between the particles. Carbon nanotubes are especially well suited for solving these issues due to their strong mechanical strength, superior electrical conductivity, high electron mobilities, excellent chemical and thermal stability, and enormous specific nanoporous surface. The hydrothermal approach was followed by chemical vapor deposition to produce a network composite of titanium dioxide nanoribbons (TNRs) and multi-walled carbon nanotubes (MWCNTs). The nanocomposite was characterized using a variety of methods. One phase of TiO2-B nanoribbons has porous pits on its surface, and MWCNTs are grown in these pits to produce a network-like structure in the nanocomposite. With a two-electrode supercapacitor configuration, the TNR/CNT gave a gravimetric capacitance of 33.33 F g-1, which was enhanced to 68.18 F g-1 in a redox-active electrolyte containing hydroquinone (HQ). Additionally, the areal capacitance per footprint was increased from 80 mF cm-2 in H2SO4 to 163.63 mF cm-2 in H2SO4/HQ. The TNR/CNT supercapacitor has superior cyclic stability than the previously reported TiO2-based electrodes, with 97.5% capacitance retention after 5000 cycles. Based on these results, it looks like the TNR/CNT supercapacitor could provide portable electronic power supplies with new ways to work in the future.

Fragmentation and release of pristine and functionalized carbon nanotubes from epoxy-nanocomposites during accelerated weathering.

There is an increasing volume of nano-enabled materials in the market. Once composites containing nano-additives are disposed of, weathering could deteriorate their structures, releasing nanoparticles and risking exposure of humans and aquatic organisms. Composite degradation due to environmental aging continues, including structural deterioration resulting in cracking, fragmentation, and release of microplastics and nano-additives to the environment. This research aims to study the degradation and release of initially embedded nanomaterials (NMs) from composites and their toxicity. The molecular interaction of carbon nanotube (CNT)/polymer composites is critical for modifying the polymer properties. This study investigated the interactions of functional multiwalled carbon nanotube (MWCNT) composites which affect their release during accelerated weathering processes. Different epoxy-MWCNT composites were prepared by filling a polymer with pure MWCNTs and MWCNTs functionalized with acid () and amine () groups. The physical and chemical changes of aged composites were characterized by gravimetric analysis, contact angle measurements, FTIR, SEM, and laser confocal microscopy. A loss of hydrophobicity was observed for composite surfaces long before surface cracks materialized. Released polymer fragments and nanoparticles were analyzed in wash water using TEM, FTIR and Raman spectroscopy. The environmental risks for long-term use of CNT-polymer composites and the influence of fillers on the extent of chemical photodegradation depended on the combination of polymer and fillers. If nanoparticles are released from the matrix, the high surface-to-volume ratio and reactivity of NMs make them highly dynamic in environmental systems. Exposure to these released NMs could negatively affect human health and the environment. This study provides fragmentation and CNT particle release data that could describe how molecular-level interactions between functionalized CNTs and epoxy polymers affect the aging and release of CNTs. A toxicity assessment based on a reactive oxygen species (ROS) formation assay and MTS assay for cell viability and activity of the released polymer and CNT fragments and leachate showed moderate levels of cytotoxicity of released materials as compared to pristine epoxy plates.

Polyurethane acrylate/multiwall carbon nanotube composites as temperature and gas sensors: Fabrication, characterization, and simulation

Polyurethane acrylate (PUA)/multiwall carbon nanotube (MWCNT) nanocomposites with potential applications in printable semiconductors were studied. For this purpose, first, the modification process of MWCNTs was performed by Feridel-Crafts acylation, then, polymerizable functional groups were connected to their external walls. After that, polyurethane pre-polymers with acrylic group ends were manufactured, and finally, the intended nanocomposites were obtained by optimum emulsion polymerization with the help of ultrasonic waves. The dispersion manner and structural specifications of MWCNTs and their interaction with polymer chains were investigated by transmission electron microscopy. The electrical conductivity property of the obtained nanocomposites with different quantities of MWCNTs as a function of temperature was studied as well and a linear relationship was attained at 1 wt% of MWCNTs. In addition, the role of polymer-based semiconducting nanocomposites for temperature sensing was discussed, and the sensitivity of the prepared temperature sensor was found to be about 0.102 MΩ/°C. In addition, the Monte Carlo simulation of this nanocomposite was performed for sensing the various gases such as H 2 , NO 2 , and NH 3 . In gas adsorption NO 2 , the adsorption energy of the PUA/3 wt% MWCNTs composite was about 50 % higher than that of pure PUA. It was shown that this nanocomposite can also be used as an appropriate gas sensor, particularly for NO 2 gas. • Polyurethane-acrylate/multiwall carbon nanotube nanocomposites with superior thermal and electrical conductivities. • The electrical conductivity of the nanocomposites as a function of temperature. • The sensitivity of the prepared temperature sensor was found to be about 0.102 MΩ/°C. • This nanocomposite can be used as an appropriate gas sensor particularly for NO 2 gas.

Selective Separation and Adsorption of Bovine Serum Albumin and Ovalbumin by Magnetic Solid-Phase Extraction (MSPE) Using Poly(Diallyldimethylammonium Chloride) Modified Cobalt Ferrite Filled Multiwalled Carbon Nanotubes as the Adsorbent

A novel poly(diallyldimethylammonium chloride) (PDDA) surface modified magnetic cobalt ferrite-filled multiwalled carbon nanotubes (CoFe2O4@MWCNTs-PDDA) composite is reported. The CoFe2O4@MWCNTs-PDDA was characterized by transmission electron microscopy, fourier transform infrared spectrometry, x-ray diffraction, and vibrating sample magnetometry and used for the selective adsorption of acidic proteins. The presence of MWCNTs served as a protective layer, which improved the stability of the magnetic composite, and also enlarged the surface area from 67 m2·g−1 to 186 m2·g−1, which provided a substrate with larger specific surface area for PDDA wrapping and enhanced the selectivity and adsorption capacity for acidic proteins. The adsorption capacity of CoFe2O4@MWCNTs-PDDA was 378.1 mg·g−1 for bovine serum albumin and 363.4 mg·g−1 for ovalbumin, an increase of approximately 20-fold, 3-fold, and 4-fold compared to CoFe2O4, CoFe2O4@PDDA and CoFe2O4@MWCNTs, respectively. The practical application of the CoFe2O4@MWCNTs-PDDA was demonstrated by processing whole blood samples for the extraction of acidic proteins. Satisfactory results were obtained by sodium dodecyl sulfate–polyacrylamide gel electrophoresis.

Ti3C2Tx MXene@NiFe layered double hydroxide derived multiple interfacial composites with efficient microwave absorption

High-performance microwave absorption materials are considered to be an effective solution to the increasing electromagnetic pollution. In this work, Ti3C2Tx MXene@NiFe-layered double hydroxide (NiFe-LDH) derived multi-interfacial FeNi3/TiN@nitrogen-doped carbon (NC)@magnetic multiwalled carbon nanotube composites were prepared by a hydrothermal process and subsequent carbothermal reduction. The phase compositions, morphology, defects and electromagnetic parameters of the composites can be regulated by the thermal treatment temperature. The reflection loss value of the composite with a thickness of only 1.6 mm can reach − 43.75 dB when the heat treatment temperature is 900 °C, and the effective absorption bandwidth is 5.5 GHz with a thickness of 2.12 mm when the heat treatment temperature is 700 °C. The synergistic effects among the associated dielectric loss, magnetic loss and the impedance matching of the samples are also systematically investigated. This work provides a new perspective and an effective approach for acquiring MXene hybrids derived high-performance microwave absorbing materials.

Effects of Hygrothermal Aging and Cyclic Compressive Loading on the Mechanical and Electrical Properties of Conductive Composites.

Conductive polymers and their composites have been widely applied in different applications, including sensing applications. Herein, we constructed a conductive composite of polypropylene, carbon black, and multi-walled carbon nanotubes (PP/CB/MWCNTs) to experimentally study its sensing behaviors in a humid thermal environment. The as-synthesized PP/CB/MWCNT composite polymer was immersed in simulated sweat in deionized water at 67 °C. Regarding their electrical and mechanical properties, different experimental parameters, such as cyclic loading and hygrothermal aging, were investigated by recording the mass changes, carrying out strain sensing experiments, and performing dynamic mechanical analyses before and after the immersion test. The results reveal that the filler content improved the rate of water absorption but decreased at higher concentrations of the solution. The sensitivity of the material decreased by up to 53% after the hygrothermal ageing and cyclic loading. Moreover, the sensitivity under cyclic compression loading decreased with an increasing immersion time, qualitatively illustrated by an effective quantum tunneling effect and conducting path model. Finally, hygrothermal aging reduced the composite's glass transition temperature. This reduction was the most significant for specimens immersed in deionized water, ascribed to the moisture absorption, reducing the molecular chain activity.

In situ prepared composite of polypyrrole and multi-walled carbon nanotubes grafted with sodium polystyrenesulfonate as ammonia gas sensor with wide detection range

Abstract NH3 gas sensors with good sensing performance including wide detection range at room temperature are highly desirable for a large variety of applications. In this work, multi-walled carbon nanotubes grafted with sodium polystyrenesulfonate (PSSNa-MWCNTs) are prepared via a controlled radical polymerization and show good dispersibility in water. The composite of polypyrrole with PSSNa-MWCNTs (PPy/PSSNa-MWCNT) is prepared by in situ vapor phase polymerization of pyrrole to fabricate NH3 gas sensors. Effects of the content of PSSNa-MWCNTs, the concentration of the oxidant, polymerization time and temperature on the gas sensing properties of the composite are investigated at room temperature. It is revealed that the composite shows much higher response magnitude than the single components. Under optimal conditions, PPy/PSSNa-MWCNT exhibits very wide detection range from 5 to 2000 ppm, and good sensing linearity over 5–20 ppm and 20–100 ppm, respectively. Moreover, the electrical responses of the composite towards NH3 gas are fast (response and recovery time to 1000 ppm NH3 gas are 16.7 s and 143.6 s, respectively), reproducible and highly selective. The interactions between PPy and MWCNTs promote the charge transfer in the composite, leading to good sensing performance and exhibiting a synergetic effect.

Development of Carbon Cloth/PMG/PAMAM/MWCNTs/ADH Bioanode for Ethanol Biofuel Cell

: More recently, enzyme-based biofuel cells have attracted special attention in different areas. The alcohol dehydrogenase (ADH) due to its cheap and easily available substrate (ethanol) is one of the dehydrogenase enzymes that has been used on researches extensively. This paper explains procurement and performance of bioanode based ADH. In present paper, we used multi-walled carbon nanotubes (MWCNTs) and polyamidoamine dendrimer (PAMAM) on poly methylene green (PMG) modified carbon cloth to fabricate bioanode for an ethanol biofuel cell. The cyclic voltammetry experiments have used to study the performance of the immobilized ADH in presence of β-nicotinamide adenine dinucleotide (NAD+) and ethanol as cofactor and substrate respectively. Also, the kinetic parameter values like kcat, KMS, and k were calculated using analytical equations based on results obtained from cyclic voltammetry. The maximum anodic current of 153.37 µA obtained from the modified bioanode at a concentration of 300 mM ethanol. The kinetic parameter values kcat, KM, and k (rate constant) for enzyme-substrate reaction calculated 1.6 ± 0.1 S-1, 4.4 mM and 1.9 × 105 M-1S-1 respectively. The results showed that the composition of PAMAM and MWCNTs provides a good electronic communication for activity of ADH based on PMG/PAMAM/MWCNTs.

Synergistic Function between Phosphorus-Containing Flame Retardant and Multi-Walled Carbon Nanotubes towards Fire Safe Polystyrene Composites with Enhanced Electromagnetic Interference Shielding.

As a universal polymer material, polystyrene (PS) is widely applied in electrical devices and construction. Thus, it is necessary to improve the flame retardancy and electromagnetic shielding properties of PS material. In this work, PS/silicon-wrapped ammonium polyphosphate/Inorganic acid-treated multi-walled carbon nanotubes composites (PS/SiAPP/aMWCNT, abbreviated as PAC) were prepared via methods of filtration-induced assembly and hot-pressing. Morphology and structure characterization demonstrated that SiAPP and aMWCNT had good dispersion in PS and excellent compatibility with the PS matrix. Thermogravimetric analysis revealed that the addition of aMWCNT to PS improved its thermal stability and carbon-forming characteristics. The peak heat release rate, the peak carbon monoxide production rate, and the peak smoke production rate of the PAC10 composite decreased by 53.7%, 41.9%, and 45.5%, respectively, while its electromagnetic shielding effectiveness reached 12 dB. These enhancements were attributed to the reason that SiAPP and aMWCNT synergistically catalyzed the char generation and SiAPP produced free radical scavengers and numbers of incombustible gases, which could decrease the oxygen concentration and retard the combustion reaction. Therefore, the assembled PS/SiAPP/aMWCNT system provides a new pathway to improve the flame retardant and electromagnetic shielding properties of PS.