Papers by Keyword: Multiwalled Carbon Nanotubes

Abstract: Thermosetting systems based on epoxy resin (RE) with the dispersion of carbon nanotubes (CNT), have been extensively studied by the development of high-performance materials with interesting mechanical, thermal and electrical properties that the thermo-rigid system achieves with the addition of CNT, and thus contribute to obtain composites with excellent performance in low amounts of this filler. However, ensuring a good dispersion of these systems is not easy, as CNTs have a great tendency to cluster due to Van der Waals interactions. To assist in the dispersion of the systems, a phosphonium-based ionic liquid, tributyl (ethyl) -phosphonium diethyl phosphate, acted with a double role, as a dispersion agent and catalyst in systems hardened with MCDEA (4,4’-methylenebis (3 - chloro-2,6-diethylaniline), which is a solid compound giving the systems high viscosity, and with the addition of LI improved the dispersion of the systems, as well as the processability in the preparation of the nanocomposites.

Abstract: In the present article aluminium matrix composites were fabricated by cold pressing and sintering technique. Multi-walled carbon nanotube (MWCNT) with various weight percentage 0.5, 1.0, 1.5 and 2.0 were added as a reinforcement to aluminium (Al) matrix. A planetary ball mill was used for mechanical alloying and even dispersion of carbon nanotubes (CNTs) in aluminium matrix. Tin (Sn) with 1.0 weight percent was used in composite to incite the sintering. The sintering was carried out at 500°C inside a tube furnace in an argon atmosphere. The morphology and structure of CNT and Al-Sn-CNT composite was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The effect of MWCNT reinforcement on microhardness and wear properties of Al-Sn-CNT composite was investigated. The hardness of composites was improved significantly with increase in CNT fraction. The reduction in the coefficient of friction and improvement in the wear resistance of the Al-Sn-CNT composite was noticed with the increase in percentage of CNTs in the composite.

Abstract: Mixed matrix membrane (MMM), a developing research area, is a membrane formed by incorporating fillers in the polymeric membrane to enhance gas separation performance. In this study, MMMs comprised of blend rubbery block copolymers of polyether block amide (Pebax-1657) with a glassy polyethersulfone (PES) polymer and multi-walled carbon nanotubes (MWCNTs) were synthesized by dry phase inversion method and explored further by gas permeability test. Pebax-1657/PES/MWCNTs membrane resulted in an increased permeability as well as CO₂/CH₄ selectivity. The Pebax-1657/PES polymer blend MMM with 10wt% of MWCNTs has shown the most superior performance of CO₂ permeability, CH₄ permeability and CO₂/CH₄ selectivity in comparison with the pure Pebax-1657 resulted in 66.3% and 11.6% difference respectively.

Abstract: Demonstrated the possibility of using multiwalled carbon nanotubes formed by means of mechanical activation of amorphous carbon for the stimulation of crop growth. By the example of pepper cultivar Golden Rain and tomato cultivar Bull Heart showed the efficacy of introducing microadditives in the form of carbon nanotubes to the ground.

Abstract: This research aims to study the effect of the functionalization of the multiwall carbon nanotubes (MWCNTs) on the mechanical property improvement of phenolic composites for bipolar plate applications in proton exchange membrane fuel cells (PEMFC). The MWCNTs were oxidized by strong acid and silanized by silane coupling agent in order to enhance the interfacial adhesion between the MWCNTs and matrix and were used as reinforcement in the phenolic composites. The silanized MWCNTs was found to improve the mechanical properties of the composites; however, they caused the decrease of electrical conductivity due to the wrapping of the MWCNTs with non-conductive silane molecules. Nevertheless, the conductivity of more than 100 S/cm is maintained to meet the DOE requirement of materials for use as bipolar plates.

Abstract: Multiwalled carbon nanotubes (MWCNT)-reinforced polymerized cyclic butylene terephthalate (pCBT) nanocomposites were prepared by in situ ring opening polymerization of cyclic butylene terephthalate oligomers (CBT). The results of differential scanning calorimetry (DSC) indicated that the melting peak located at the low temperature (Tm1) increased and that at higher temperature (Tm2) decreased with the increasing of content of the MWCNT. During the cooling the MWCNT served as nucleation points from where crystallization can start. The more the MWCNT in the system the earlier the crystallization starts. The Morphological investigations performed by scanning electron microscopy (SEM) shown that the MWCNT were embedded in the matrix and held tightly by the matrix. The modulus and strength increased with MWCNT concentration in the nanocomposites, however, the elongation at break, absorbed energy at break and impact strength were decreased with the increasing of MWCNT content.

Abstract: Commercially available Multiwalled Carbon Nanotubes (MWCNTs) were refluxed with nitric acid in order to improve the density of the acidic surface functional groups. The formation of oxygen containing functional groups may lead to surface enhancement of MWCNTs for further modifications. The crude MWCNTs were refluxed in nitric acid at 100 °C for time ranging between 3 to 24 h. The influence of treatment time on crystalline structure was investigated using X-Ray Diffraction (XRD); the results confirmed that all treated MWCNTs are crystalline. The density of the surface functional groups on treated MWCNTs was examined by Fourier Transform Infrared (FTIR). The FTIR spectrums revealed a strong vibration band at 1739, 1219, 1369 cm^-1 that indicates covalently bound acidic surface functional groups existed on the treated MWCNTs. The amount of acidic groups increased with the reflux time up to 15 h treatment as measured by an acid-base Boehm titration. The vibrational spectroscopy of these functional groups also increased with the increasing reflux time.

Abstract: Multiwalled carbon nanotubes (MWCNTs) as an excellent supporter covered with a thick layer of cobalt phthalocyanine (CoPc) were prepared by in-situ synthesis. Platinum particles were adopted to enhance the conductivity of CoPc-MWCNTs. The final nanocomposite Pt-CoPc-MWCNTs was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Strong aromatic π-π stacking between MWCNTs and CoPc made CoPc in-situ forming on MWCNTs. With homogeneous thickness of CoPc covered on the MWCNTs and Pt particles equally distributed, the nanocomposite was used as electrocatalyst. The electrochemical properties of the composite got researched by casting the dispersion of Pt-CoPc-MWCNTs on the glassy carbon electrode. Compared with other modified electrodes, Pt-CoPc-MWCNTs/GC electrode exhibited excellent electrochemical activity towards dopamine (DA) and uric acid (UA). Linear responses for DA and UA were obtained in the ranges of 5 to 170 μM and 5 to 100 μM, and limits of detection were 2.6 and 1.4 μM (S/N = 3), respectively. Simultaneous detection of DA and UA in the presence of ascorbic acid (AA) also displayed selective property, with no interference to each other.