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نتیجه جستجو - Nanocomposites

تعداد مقالات یافته شده: 18
ردیف عنوان نوع
1 Nanoinfiltration behavior of carbon nanotube based nanocomposites with enhanced mechanical and electrical properties
رفتار نانوفیلتراسیون نانوکامپوزیت های مبتنی بر نانولوله کربنی با خواص مکانیکی و الکتریکی بهبود یافته-2021
In this work, carbon nanotube (CNT) based nanocomposites with high mass fraction are proposed by in-situ bridging carbon matrix into CNT paper through optimized chemical vapor infiltration (CVI). Nanoinfiltration behavior of CNTs is basically investigated under the CVI process. The contact between each CNT can be strengthened and the conductive pathways can be established, resulting in the better mechanical and electrical properties. Compared with the pristine CNT paper, the CNT/C composite after pyrolysis process confirms a remarkable advance in tensile strength (up to 310 ± 13 MPa) and Young’s modulus (up to 2.4 ± 0.1 GPa). Besides, a notable feature of electrical conductivity also shows an improvement up to 8.5 S/cm, which can be attributed to the mass fraction of CNT (41 wt%) breaking the limits of percolation thresholds and the efficient densification of this sample to establish the conductive pathways. This study has a broad application in the development of the multi-functional electrical and engineering materials.
Keywords: Carbon nanotube | Chemical vapor infiltration (CVI) | Nanocomposites
مقاله انگلیسی
2 Chemical adsorption on 2D dielectric nanosheets for matrix free nanocomposites with ultrahigh electrical energy storage
جذب شیمیایی روی نانوصفحات دی الکتریک دوبعدی برای نانوکامپوزیت های بدون ماتریس با ذخیره انرژی الکتریکی فوق العاده بالا-2021
Relaxor ferroelectric polymers display great potential in capacitor dielectric applications because of their excellent flexibility, light weight, and high dielectric constant. However, their electrical energy storage capacity is limited by their high conduction losses and low dielectric strength, which primarily originates from the impact-ionization-induced electron multiplication, low mechanical modulus, and low thermal conductivity of the dielectric polymers. Here a matrix free strategy is developed to effectively suppress electron multiplication effects and to enhance mechanical modulus and thermal conductivity of a dielectric polymer, which involves the chemical adsorption of an electron barrier layer on boron nitride nanosheet surfaces by chemically adsorbing an amino-containing polymer. A dramatic decrease of leakage current (from 2.4  106 to 1.1  107 A cm2 at 100 MV m1) and a substantial increase of breakdown strength (from 340 to 742 MV m1) were achieved in the nanocompostes, which result in a remarkable increase of discharge energy density (from 5.2 to 31.8 J cm3). Moreover, the dielectric strength of the nanocomposites suffering an electrical breakdown could be restored to 88% of the original value. This study demonstrates a rational design for fabricating dielectric polymer nanocomposites with greatly enhanced electric energy storage capacity.
Keywords: Boron nitride nanosheets | Electron barrier layer | Relaxor ferroelectric polymers | Nanocomposites | Electrical energy storage
مقاله انگلیسی
3 Effect of CNT additives on the electrical properties of derived nanocomposites (experimentally and numerical investigation)
تأثیر افزودنی‌های CNT بر خواص الکتریکی نانوکامپوزیت‌های مشتق‌شده (بررسی تجربی و عددی)-2021
In this work, two simulations models have been developed to study the electrical percolation and the electrical conductivity of epoxy-based nanocomposite containing Multi-walled Carbon Nanotubes. The models are based on resistor-model and finite element analysis. The former was evaluated using MATLAB code and the finite element analysis using DIGIMAT software. The maximum tunneling distance and its influence on the percolation probability and final electrical conductivity were studied. Electrical measurements on the samples were conducted for numerical validation. The experimental data showed a percolation achievement around 2 wt%, which was confirmed in the numerical simulations. This study provides evidence of the effectiveness of the resistor model and finite element method approach to predict the electrical conductivity of nanocomposites.
Keywords: Polymer-matrix composites (PMCs) | Nanocomposites | Carbon nanotube | Electrical properties | Computational modelling
مقاله انگلیسی
4 Electro-conductive carbon nanofibers containing ferrous sulfate for bone tissue engineering
Electro-conductive carbon nanofibers containing ferrous sulfate for bone tissue engineering-2021
The application of electroactive scaffolds can be promising for bone tissue engineering applications. In the current paper, we aimed to fabricate an electro-conductive scaffold based on carbon nanofibers (CNFs) containing ferrous sulfate. FeSO4⋅7H2O salt with different concentrations 5, 10, and 15 wt%, were blended with polyacrylonitrile (PAN) polymer as the precursor and converted to Fe2O3/CNFs nanocomposite by electrospinning and heat treatment. The characterization was conducted using SEM, EDX, XRD, FTIR, and Raman methods. The results showed that the incorporation of Fe salt induces no adverse effect on the nanofibers morphology. EDX analysis confirmed that the Fe ions are uniformly dispersed throughout the CNF mat. FTIR spectroscopy showed the interaction of Fe salt with PAN polymer. Raman spectroscopy showed that the incorporation of FeSO4⋅7H2O reduced the ID/IG ratio, indicating more ordered carbon in the synthesized nanocomposite. Electrical resistance measurement depicted that, although the incorporation of ferrous sulfate reduced the electrical conductivity, the conductive is suitable for electrical stimulation. The in vitro studies revealed that the prepared nanocomposites were cytocompatible and only negligible toxicity (less than 10%) induced by CNFs/Fe2O3 fabricated from PAN FeSO4⋅7H2O 15%. Although various nanofibrous composite fabricated with Fe NPs have been evaluated for tissue engineering applications, CNFs exhibited promising properties, such as excellent mechanical strength, biocompatibility, and electrical conductivity. These results showed that the fabricated nanocomposites could be applied as the bone tissue engineering scaffold.
Keywords: Bone tissue engineering | Electrospinning | Carbon nanofiber | Ferrous sulfate
مقاله انگلیسی
5 Highly thermo-conductive yet electrically insulating material with perpendicularly engineered assembly of boron nitride nanosheets
مواد بسیار رسانای حرارتی و در عین حال عایق الکتریکی با مونتاژ عمودی مهندسی شده نانوصفحات نیترید بور-2021
With rapid evolution of advanced microelectronic devices, thermally conductive polymeric materials with impressive through-plane thermal conductivity (κ⊥) and remarkable electrical insulating properties are urgently demanded for efficient thermal management. Assembly of boron nitride nanosheets (BNNS) into polymer matrix with vertically interconnected conformation was usually adopted. However, impeded by inferior oriented degree and insufficient overlapped interconnection of BNNS, polymer/BNNS nanocomposites still suffered from a limited enhancement of κ⊥. In this work, we firstly prepared regenerated cellulose (RC)/BNNS filaments with high thermal conductivity via wet-spinning method. Then, a tailored polydimethylsiloxane (PDMS)/(RC/BNNS) filaments nanocomposite with hierarchical assembled architectures is successfully fabricated with customizedmold vacuum impregnation. Numerous bunches of microscopical hybrid filaments penetrate through the nanocomposite from the bottom to the up, while vertically aligned microscopical BNNS with efficient filler interconnections confined within filaments provide many uniaxial thermal pathways. Attributed to tactfully engineered phonon pathways, the as-prepared material exhibits a remarkable κ⊥ up to 5.13 W/m K at 27.05 vol% BNNS loading, outperforming the characters in most literatures. Along with excellent electrical resistance and extraordinary thermal management performances, this type of nanocomposite with hierarchical structures provides an effective strategy to thickness-direction heat transfer issues of electronic devices.
Keywords: Through-plane thermal conductivity | Polymer | Boron nitride nanosheets | Vertical orientation
مقاله انگلیسی
6 Definition of “b” exponent and development of power-law model for electrical conductivity of polymer carbon nanotubes nanocomposites
تعریف توان "b" و توسعه مدل قدرت قانون برای هدایت الکتریکی نانوکامپوزیت های نانولوله های کربن پلیمر-2020
In this article, the conventional power-law model for electrical conductivity of polymer carbon nanotubes (CNT) nanocomposites (PCNT) is linked with a developed model. The main goal is to define the “b” exponent and develop the power-law model for conductivity of PCNT. The interphase region surrounding nanoparticles and the CNT waviness, which affect the percolation threshold, the fraction of networked CNT and the effective volume fraction of CNT are taken into account. The developed model expresses that CNT concentration, CNT length and interphase thickness positively handle the conductivity of PCNT, while thick and waved CNT cause the adverse effect. Moreover, the calculations of the developed model accurately follow the experimental results of conductivity and “b” raises as CNT concentration increases.
Keywords: Polymer CNT nanocomposites | Electrical conductivity | Power-law model | Interphase region | Modeling
مقاله انگلیسی
7 Scaling laws of Mullins effect in nitrile butadiene rubber nanocomposites
مقیاس بندی قوانین اثر مولین در نانوکامپوزیت های لاستیکی بوتادین نیتریل-2020
Rubber nanocomposites experiencing cyclic deformation undoubtedly exhibit Mullins effect whose underlining mechanisms are not yet clear. Herein this effect in nitrile butadiene rubber nanocomposites is systematically investigated for revealing the influences of pre-strain interval, loading and unloading velocities, temperature, filler type and content, as well as crosslinking agent. The results show that the recovery hysteresis energy and accumulative softening energy of the nanocomposites can be superposed onto master curves as a function of microscopic strain of the rubber phase, revealing that both involving the viscoelastic deformation of the rubber phase. Especially the recovery hysteresis highly depending on temperature and loading and unloading velocities is connected to the viscoelasticity of nonideally crosslinked rubber network in the nanocomposites. On the other hand, the accumulative softening energy loss comes from recovery retardation of rubber chains and is somewhat sensitive to the filler, temperature and crosslinking agent. The investigation would be instructive to clarify the physical origin of Mullins effect to produce low dissipation rubber nanocomposites.
Keywords: Mullins effect | Energy loss | Nanocomposites
مقاله انگلیسی
8 Machine-learning assisted coarse-grained model for epoxies over wide ranges of temperatures and cross-linking degrees
یادگیری ماشین به کمک مدل دانه درشت برای epoxies در طیف گسترده ای از درجه حرارت و درجه اتصال متقابل-2019
We present a practical computational framework for the coarse-graining of cross-linked epoxies by developing a machine-learning technique, which integrates molecular dynamics simulations with artificial neural network (ANN) assisted particle swarm optimization (PSO) algorithm. Key features of the framework include two as- pects: (1) determining the bonded interactions via the iterative Boltzmann inversion method to emulate the local structures of the epoxies and, (2) optimizing the nonbonded interaction potentials through the machine- learning approach to reproduce the mechanical properties. Such machine-learning based technique is computa- tionally efficient in searching for the optimal solution of nonbonded potential parameters and enables the CG model to become transferable within a wide range of cross-linking degrees. This is mainly attributed to the fact that ANN can give good predictions based on training database obtained from CG simulations and thus greatly accelerates the PSO algorithm in achieving the optimal solution. On the basis of the DOC-transferable CG model, the cohesive interaction strength is phenomenologically adjusted to preserve the temperature-dependent prop- erties. The CG model allows the mechanical properties of cross-linked epoxies to be predicted with reasonable accuracy over wide ranges of cross-linking degrees and temperature. The proposed framework will become highly beneficial to the design of high performance epoxy-matrix nanocomposites.
Keywords: Machine-learning approach | Cross-linked epoxy | Coarse-grained model | Molecular dynamics
مقاله انگلیسی
9 Application of the voltammetric electronic tongue based on nanocomposite modified electrodes for identifying rice wines of different geographical origins
کاربرد زبان الکترونیکی ولتامتری بر اساس الکترودهای اصلاح شده نانو کامپوزیت برای شناسایی شراب برنج با منشأ جغرافیایی مختلف-2019
In the study, the voltammetric electronic tongue based on three nanocomposites modified electrodes was applied for the identification of rice wines of different geographical origins. The nanocomposites were prepared by gold and copper nanoparticles in the presence of conducting polymers (polymer sulfanilic acid, polymer glutamic acid) and carboxylic multi - walled carbon nanotubes. The modified electrodes showed high sensitivity to guanosine - 5 - monophosphate disodium salt, tyrosine and gallic acid which have good correlation with the geographical origins of rice wines. Scanning electron microscopy was performed to display the surface morphologies of the nanocomposites, and cyclic voltammetry was applied to study the electrochemical behaviors of the taste substances on the electrode surfaces. Four types of electrochemical parameters (pH, scan rates, accumulation potentials and time) were optimized for getting a low limit of the detection of each taste substance. The geographical information of rice wines was obtained by the modified electrodes based on two types of multi - frequency large amplitude pulse voltammetry, and “area method” was applied for extracting the feature data from the original information obtained. Based on the area feature data, principal component analysis, locality preserving projection (LPP), and linear discriminant analysis were applied for the classification of the rice wines of different geographical origins, and LPP presented the best results; extreme learning machine (ELM) and alibrary for support vector machines were applied for predicting the geographical origins of rice wines, and ELM performed better.
Keywords: Nanocomposites modified electrodes | Conducting polymer | Multi - walled carbon nanotubes | Rice wine | Pattern recognition
مقاله انگلیسی
10 نانو کامپوزیت‌های Cu پوشیده از پروتئین دارای نانو خوشه‌های SWCNT به‌عنوان یک گزینه جدید در پلتفرم با عملکرد بالا برای حسگر زیستی بدون آنزیم ارگانوفسفات-ها
سال انتشار: 2017 - تعداد صفحات فایل pdf انگلیسی: 26 - تعداد صفحات فایل doc فارسی: 23
یک نانوکامپوزیت زیست سازگار شامل آلبومین سرم گاوی (BSA) نانو خوشه‌های مس (CuNCs @ BSA) و نانولوله‌های کربنی تک جداره (SWCNT) برای ساخت بیوسنسور الکتروشیمیایی بسیار حساس برای پاراکسون به‌عنوان مدلی از ارگانوفسفات¬ها سنتز شد.UV-Vis ، فلورسانس و مادون‌قرمز تبدیل فوریه (FTIR) نشان دادند که BSA محبوس شده در فیلم نانوکامپوزیت در ساختار ثانویه آن تغییر یافته است طوری که یک فعالیت آنزیمی مانند فعالیت با هدایت الکتریکی بالای نانو خوشه‌های مس به دام افتاده ایجاد می‌کند. همچنین، مورفولوژی و ساختار نانو کامپوزیت‌های تهیه‌شده توسط میکروسکوپ الکترونی عبوری (TEM) و میکروسکوپ الکترونی روبشی (SEM) بررسی شد. در نانوکامپوزیت آماده‌شده، CuNCs @ BSA به‌عنوان یک نگه‌دارنده رسانا و همچنین به‌عنوان یک جمع کننده از مراکز فعال اکسایش-کاهش در سطح الکترود عمل می‌کند و SWCNT فعالیت الکتروکاتالیستی همراه با رسانایی سطح الکترود کربن شیشه‌ای (GCE) را بهبود می‌بخشد. بیوسنسور ساخته‌شده حساسیت عالی، ثبات قابل‌قبول، پاسخ سریع و فعالیت الکتروکاتالیستی بالا نسبت به کاهش پاراکسون از خود نشان داد. کاهش جریان پیک در مقابل غلظت پاراکسون در محدوده 50 نانومولار تا 0.5 میکرومولار و 0.5 تا 35 میکرومولار با محدودیت تشخیص 12.8 نانومولار خطی بود. خصوصیات قابل‌توجه الکتروکاتالیستی الکترود تولیدشده نسبت به پاراکسون نشان داد که این نانوکامپوزیت دارای پتانسیل خوبی برای ساخت حسگرهای زیستی الکتروشیمیایی بدون آنزیم، بیوالکترونیک و پیشرفته‌ترین دستگاه‌های پزشکی در آینده است.
کلمات کلیدی: بیوسنسر آنزیمی | حسگرهای زیستی الکتروشیمیایی | پاراکسون | نانو خوشه‌های مس | ارگانوفسفات ها | SWCNT
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