Study of the Diffusion Behavior of Seawater Absorption in Multi-Walled Carbon Nanotubes/Halloysite Nanotubes Hybrid Nanofillers Modified Epoxy-Based Glass/Carbon Fiber Composites

In the maritime industry, cost-effective and lightweight Fiber Reinforced Polymer (FRP) composites offer excellent mechanical properties, design flexibility, and corrosion resistance. However, their reliability in harsh seawater conditions is a concern. Researchers address this by exploring three approaches: coating fiber surfaces, hybridizing fibers and matrices with or without nanofillers, and interply rearrangement. This study focuses on evaluating the synergistic effects of interply rearrangement of glass/carbon fibers and hybrid nanofillers, specifically Multi-walled carbon nanotubes (MWCNT) and Halloysite nanotubes (HNT). The aim is to enhance impact properties by minimizing moisture absorption. Hybrid nanocomposites with equal-weight proportions of two nanofillers: 0 wt.%, 1 wt.%, and 2 wt.% were exposed to seawater for 90 days. Experimental data was subjected to modelling through the application of Predictive Fick’s Law. The study found that the hybrid composite containing 2 wt.% hybrid nanofillers exhibited a 22.10% increase in impact performance compared to non-modified counterparts. After 90 days of seawater aging, the material exhibited enhanced resistance to moisture absorption (15.74%) and minimal reduction in impact strength (8.52%) compared to its dry strength, with lower diffusion coefficients.

New amperometric glucose biosensor by entrapping glucose oxidase into chitosan/nanoporous ZrO_2/multiwalled carbon nanotubes nanocomposite film

A new nanocomposite material for construction of glucose biosensor was prepared. The biosensor was formed by entrapping glucose oxidase(Gox) into chitosan/nanoporous ZrO2/multiwalled carbon nanotubes nanocomposite film. In this biosensing thin film, the multiwalled carbon nanotubes can effectively catalyze hydrogen peroxide and nanoporous ZrO2 can enhance the stability of the immobilized enzyme. The resulting biosensor provides a very effective matrix for the immobilization of glucose oxidase and exhibits a wide linear response range from 8 μmol/L to 3 mmol/L with a correlation coefficient of 0.994 for the detection of glucose. And the response time and detection limit of the biosensor are determined to be 6 s and 3.5 μmol/L, respectively. Another attractive characteristic is that the biosensor is inexpensive, stable and reliable.

Biodegradable Chitosan/Multiwalled Carbon Nanotube Composite for Bone Tissue Engineering

In this work the influence of multiwalled carbon nanotubes (MWCNT) on mechanical properties was evaluated also the osteoinduction mechanism in Chitosan/MWCNT composite is reported. The morphology and the mechanical properties of the scaffolds were controlled by varying solvent ratios, quenching temperatures and carbon nanotubes concentration. In vitro cell culture of Sprague-Dawley rat’s osteoblasts was used to evaluate the phenotype expression of cells in the scaffolds. The presence of MWCNT in a chitosan matrix improving its mechanical properties and sustain osteoblast growth and differentiation that represent a potential application of the Chitosan/MWCNT as biomaterial for bone tissue engineering.

Development of Chitosan/Poly(L-Lactide)/Multiwalled Carbon Nanotubes Scaffolds for Bone Tissue Engineering

This work focuses to improve the mechanical properties and investigates the growth of osteoblasts on a degradable chitosan/poly(L-lactide)/carbon nanotubes composite for tissue engineering. The morphological and mechanical properties characterizations were performed using scanning electronic microscopy (SEM) and rheometrics analysis system (RSA). Osteoblasts differentiation was determined by alkaline phosphatase activity, total number cells by an Alamar Blue assay, cell attachment and proliferation were visualized qualitatively using SEM, mineralization was characterized by transformed infrared spectroscopy, energy dispersive spectroscopy, and X-ray diffraction. The results suggest that the chitosan/poly(L-lactide)/multiwalled carbon nanotubes composites exhibit the ability to promote cell adhesion, proliferation, and differentiation on their surface.

Laccase biosensor using magnetic multiwalled carbon nanotubes and chitosan/silica hybrid membrane modified magnetic carbon paste electrode

A simple and rapid strategy to construct laccase biosensor for determination of catechol was investigated. Magnetic multiwalled carbon nanotubes (MMCNT) which possess excellent capability of electron transfer were prepared by chemical coprecipitation method. Scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) were used to identify its surfacetopography and magnetization, respectively. Laccase was immobilized on the MMCNT modified magnetic carbon paste electrode by the aid of chitosan/silica (CS) hybrid membrane. Using current-time detection method, the biosensor shows a linear response related to the concentration of catechol in the range from 10-7 to 0.165×10-3 mol/L. The corresponding detection limit is 3.34×10-8 mol/L based on signal-to-noise ratios (S/N) ≥3 under the optimized conditions. In addition, its response current retains 90% of the original after being stored for 45 d. The results indicate that this proposed strategy can be expected to develop other enzyme-based biosensors.

Synthesis and thermal stability of multiwall carbon nanotubes reinforced aluminum metal matrix composites

Multiwall carbon nanotubes（MWNTs） reinforced aluminum composites were synthesized by hot press sintering. The thermal stability of MWNTs in the composite was investigated by transmission electron microscopy（TEM）. The results show that the impurities drop from 2% to 0.11% after the MWNTs are soaked with 95%H2SO4 and 66%HNO4 acids in an ultrasonator and washed with distilled water. In hot pressed composites, MWNTs distribute between aluminum powders and do not react with aluminum. When the composite was held at 800℃ for 1h, MWNTs react with aluminum and form Al4C3 phase, which are small polygons and distribute in the aluminum grains. Although Al4C3 phase still forms when the composite was held at 1000℃ for 1h, its morphology changes to a continuous band and distributes along the origin aluminum powder boundaries. So MWNTs are unstable in aluminum matrix composites that are kept above the liquidus temperature of aluminum.

Electroless deposition of Cu on multiwalled carbon nanotubes

Copper has been deposited on the surface of multiwailed carbon nanombes （MWNTs） and inside MWNTs by electroless deposition. The as-prepared Cu-MWNT composite materials have been characterized by X-ray diffractometer （XRD）, transmission electron microscopy （TEM）, and electrochemical measurement. XRD analyses showed that Cu was a face-centered cubic （fcc） structure. The average size of Cu was calculated by Scherrer＇s formula from XRD data, and it was 11 nm. TEM revealed that Cu grains on the surface of MWNTs were uniform with the sizes of about 30-60 nm. The electrochemical measurement indicated that Cu-MWNT composite materials possessed fine electron conductivity.

Glass-Reinforced Plastic Filled by Multiwall Carbon Nanotubes and Their Modified Forms

The effect of modifying the surface of multiwall carbon nanotubes (CNT’s) by oxygen and nitrogen on the strength characteristics of the fiberglass filled with them was investigated by testing for tension and bending. The method of obtaining nitrogen-containing nanostructures is developed. It was shown that in the epoxide system LR285-LH286 hydrophobic CNT’s (outgoing) at introducing into the catalyst polymerization of LH286, increase the strength with respect to unreinforced CNT’s by 48% - 54%. Oxidized CNT’s (200 A?h/kg) introduced into the resin LR285 increase the strength by 59%. The distribution of the filler particles in size, both in the epoxy resin and in the catalyst, depends on their concentration nonlinear, and correlates with the strength characteristics of the composite.

A glance on the effects of temperature on axisymmetric dynamic behavior of multiwall carbon nanotubes

In this paper the effects of temperature on the radial breathing modes （RBMs） and radial wave propaga- tion in multiwall carbon nanotubes （MWCNTs） are inves- tigated using a continuum model of multiple elastic isotropic shells. The van der Waals forces between tubes are simulated as a nonlinear function of interlayer spacing of MWCNTs. The governing equations are solved using a finite element method. A wide range of innermost radius-to-thickness ratio of MWCNTs is considered to enhance the investigation. The presented solution is verified by comparing the results with those reported in the literature. The effects of temperature on the van der Waals interaction coefficient between layers of MWCNTs are examined. It is found that the variation of the van der Waals interaction coefficient at high temperature is sensible. Subsequently, variations of RBM frequencies and radial wave propagation in MWCNTs with temperatures up to 1 600 K are illustrated. It is shown that the thick MWC- NTs are more sensible to temperature than the thin ones.

Electrocatalytic Reduction of Oxygen at Perovskite (BSCF)-MWCNT Composite Electrodes

A composite paste electrode based on Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF)—initially synthesized by solgel method—and multiwall carbon nanotube (MWCNT) as a cathode in fuel cells is developed. The composite pastes are prepared by the direct mixing of BSCF:MWCNT at 90:10, 80:20 and 70:30 (% w/W). These electrodes are then characterized by the x-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherm, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The XRD and SEM confirm the inclusion and the uniform dispersal of the MWCNT within BSCF, respectively. The nitrogen adsorption isotherm study shows that the porosity of the composite paste electrode has been improved by two-fold from the BSCF electrode. The EIS and CV demonstrate that the higher ratios of MWCNT in the composites are critical in improving the electronic conductivity as well as the kinetics. It is also noticeable that the electrode has increased the catalysis of oxygen in 0.1 M KOH (pH 12.0). Cyclic voltammetric studies on the oxygen reduction reaction (ORR) suggest that the incorporation of MWCNT is vital in improving the electrode (cathode) properties of a fuel cell.

Synthesis, Characterization and Gas Sensing Properties of Graphene Oxide-Multiwalled Carbon Nanotube Composite

Graphene oxide （GO）-multiwalled carbon nanotube （MWCNT） composite was synthesized and characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, micro Raman, Fourier transform infrared and ultraviolet-visible near infrared spectroscopy techniques. Spectral characteris- tics of cladding modified fiber optic gas sensors were studied for various concentrations of ammonia, ethanol and methanol at 27 ℃. Thickness of the gas sensing layer was controlled by varying the concentration of composite in ethanol medium （0.5 and 1 mg/mL） for three times dipping process. The O.S mg/ mL concentrated GO-MWCNT coated sensor showed 1.20, 1.40 and 1.15 times higher sensitivity than the GO coated sensor for ammonia, ethanol and methanol vapors, respectively. Furthermore, it exhibited 1.50, 1.80 and 1.80 times better sensitivity than 1 mg/mL concentrated GO-MWCNT coated sensor for ammonia, ethanol and methanol vapors, respectively. The presence of functional groups in GO increased the sen- sitivity. This is mainly attributed to the effective electron charge transfer between the composite materials and analytes.

Stripping voltammetric determination of Cd(Ⅱ)based on multiwalled carbon nanotube functionalized with 1-(2-pyridylazo)-2-naphthol

The present work has focused on the modification of multiwalled carbon nanotube with a ligand,l-（2-pyridylazo）-2-naphthol, and its potential application for the development of a new,simple and selective modified glassy carbon electrode for stripping voltammetric determination of Cd（Ⅱ）.The analytical curve for Cd（Ⅱ） ions covered the linear range varying from 0.8 up to 220.4μgL^（-1）.The limit of detection was found to be 0.1μgL^（-1）,while the relative standard deviation（RSD） at 50.0μgL^（-1） was 1.8%（n=5）.This modified electrode was successfully applied for determination of Cd（Ⅱ） in some water samples.

羧基化多壁碳纳米管对T-1000碳纤维/环氧树脂复合材料性能的影响

对多壁碳纳米管进行了表面羧基化处理,将羧基化碳纳米管添加到环氧树脂基体中,通过湿法缠绕工艺制备出具有高性能的T1000碳纤维增强环氧树脂复合材料。结果表明,复合材料的界面性能和耐热性能得到改善,当羧基化碳纳米管质量含量为1%时,复合材料的层间剪切强度提高了近29%。

基于纳米金与碳纳米管-纳米铂-壳聚糖纳米复合物固定癌胚抗原免疫传感器的研究

采用纳米金(nano-Au)、多壁碳纳米管-纳米铂-壳聚糖的纳米复合物(MWNT-Pt-CS)及电子媒介体硫堇(Th)固载抗体制得高灵敏癌胚抗原免疫传感器.首先,于壳聚糖溶液中用NaBH4还原H2PtCl6,并将多壁碳纳米管分散于其中制得碳纳米管-纳米铂-壳聚糖纳米复合物,并将其滴涂在玻碳电极上成膜;然后,吸附电子媒介体硫堇制得硫堇/碳纳米管-纳米铂-壳聚糖(Th/MWNT-Pt-CS)修饰电极.利用壳聚糖和硫堇分子中大量的氨基固定纳米金并吸附癌胚抗体(anti-CEA);最后,用辣根过氧化物酶(HRP)封闭活性位点从而制得高灵敏电流型免疫传感器.在优化的实验条件下,该传感器响应的峰电流值与癌胚抗原(carcinoembryonic antigen)浓度在0.5～10和10～120ng/mL的范围内保持良好的线性关系,检测限为0.2ng/mL.

基于CMWCNT/Nafion的增强型离子聚合物金属复合材料的制备及致动性能

离子聚合物金属复合材料(IPMC)是一种新型的电活性材料,具有体积小、质量轻、驱动电压低等优点,但驱动力小、稳定工作时间短等问题限制着其柔性致动性能。提出了一种基于银基IPMC的增强型致动器,通过在IPMC的基底聚合物中掺杂羧基化多壁碳纳米管(CMWCNT),来提高IPMC的整体机械性能和致动性能。其中,掺杂质量分数0.5%CMWCNT的IPMC的最大尖端位移和驱动力分别增加至未优化银基IPMC的1.60倍与2.32倍,该性能的提升归因于CMWCNT良好的导电性和羧基对水合阳离子迁移的加速作用。与未优化的银基IPMC相比,掺杂质量分数0.5%CMWCNT时IPMC驱动速率可提升至3.57倍。研究结果可为IPMC在各领域的应用发展提供参考。

壳聚糖-碳纳米管修饰电极的电催化作用研究

报道了一种新型的壳聚糖-碳纳米管修饰电极(MC/GCE)的电化学特性。此修饰电极对神经递质去甲肾上腺素(NE)表现出很强的电催化效应,在pH 5.5的磷酸盐缓冲溶液中,NE的峰电流与浓度在5.0×10-6～1.0×10-4mol/L范围内呈线性关系。此外,其它生物分子如多巴胺(DA)、尿酸(UA)在MC/GCE上也有很好的电化学响应。修饰电极表现出很好的稳定性和选择性。

β环糊精-碳纳米管/壳聚糖自组装膜修饰电极在过量抗坏血酸存在下测定多巴胺

基于β环糊精和碳纳米管可通过范德华力形成复合物，利用壳聚糖分子以静电引力吸附富集碳纳米管-β环糊精，采用层层自组装制备了β环糊精．碳纳米管／壳聚糖玻碳修饰电极，并研究了多巴胺在修饰电极上的电化学行为。在抗坏血酸和多巴胺共存体系中，二者的氧化峰电位相差约163mv，据此建立了多巴胺的电化学选择性测定，峰电流与浓度在1．0×10^-6～7．0×10^-5mol／L范围内呈良好的线性关系，检出限为0．3umol／L。

复合电沉积Ni-MWCNTs及镍电结晶的研究

研究了水平阴极方式复合电沉积Ni-MWCNTs(Ni-多壁碳纳米管)。采用硫酸镍基础电解液,添加适当表面活性剂和光亮剂,MWCNTs为2～2.5g/L,电流密度为2.5A/dm2时,获得的Ni-MWCNTs沉积层结构致密,复合沉积层中MWCNTs含量达22.45%。复合电沉积层表面微观形貌照片显示,MWCNTs在复合电沉积层中占主要体积,镍的电结晶形态呈球形,结晶点位置位于MWCNTs管壁缺陷处及部分管端处,MWCNTs的管端和管壁缺陷处的Ni晶粒相互连接,形成牢固的复合沉积层。复合电沉积层中MWCNTs含量受电解液中MWCNTs浓度、电流密度以及光亮剂影响,在MWCNTs上的Ni沉积层连续性直接受MWCNTs管壁上缺陷的数量和连续性影响,形成晶核的缺陷尺度至少在1nm以上。

用纳米铂-多壁碳纳米管-壳聚糖修饰玻碳电极计时电流法测定过氧化氢

将多壁碳纳米管(MWCNT's)1mg分散在5g·L^(-1)壳聚糖溶液中,并滴涂在玻碳电极表面,将上述电极置于氯铂酸(1+99)溶液中,于电位-0.2V下电沉积90s,制得纳米铂-多壁碳纳米管-壳聚糖修饰玻破电极(nanoPt/MWCNT's-CTS/GCE)。采用扫描电子显微镜对该电极表面结构进行了表征,并用循环伏安法和计时电流法对该电极的电化学性能进行了研究。试验表明:在pH 7.0的0.1mol·L^(-1)磷酸盐底液中,该传感器对过氧化氮具有明显的电催化还原作用。过氧化氢浓度在6.30×10^(-7)~1.52×10^(-3)mol·L^(-1)范围内与还原峰电流呈线性关系,检出限(3S/N)为2.13X10^(-1)mol·L^(-1)。对0.35邪mmol·L^(-1)过氧化氢标准溶液连续测定8次,测定值的相对标准偏差(n=8)为0.27%。

锂硫电池用气相生长碳纤维增强硫-多壁碳纳米管复合正极的影响(英文)

制备了锂硫电池用硫-多壁碳纳米管纳米复合材料,并分别采用气相生长碳纤维(VGCFs)和导电炭黑作为复合正极的导电添加剂,通过形貌表征(SEM)、恒流充放电测试和交流阻抗分析(EIS)研究VGCFs对硫-多壁碳纳米管复合正极的影响。结果表明:采用VGCFs作添加剂的硫-多壁碳纳米管复合电极具有三维网状结构,其首次放电比容量为1254 mA·h/g,40次循环后容量保持在716 mA·h/g。与采用导电炭黑为添加剂的电极相比,采用VGCFs为添加剂的电极具有更高的活性物质利用率和更好的循环稳定性。相互搭接的纤维状VGCFs可形成稳定的导电网络,抑制正极材料及残存放电产物的团聚堆积,维持电极的多孔性,从而改善电池的电化学性能。