Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties

Elements Of X Ray Diffraction

Carbon nanotubes (CNTs) demonstrate remarkable electrical, thermal, and mechanical properties, which allow a number of exciting potential applications. In this article, we review the most recent progress in research on the development of CNT-polymer composites, with particular attention to their mechanical and electrical (conductive) properties. Various functionalization and fabrication approaches and their role in the preparation of CNT-polymer composites with improved mechanical and electrical properties are discussed. We tabulate the most recent values of Young's modulus and electrical conductivities for various CNT-polymer composites and compare the effectiveness of different processing techniques. Finally, we give a future outlook for the development of CNT-polymer composites as potential alternative materials for various applications, including flexible electrodes in displays, electronic paper, antistatic coatings, bullet-proof vests, protective clothing, and high-performance composites for aircraft and automotive industries.

Recent Advances in Research on Carbon Nanotube–Polymer Composites

Open literature publications, in the period from 2010 to the end of January 2018, on refractory high entropy alloys (RHEAs) and refractory complex concentrated alloys (RCCAs) are reviewed. While RHEAs, by original definition, are alloys consisting of five or more principal elements with the concentration of each of these elements between 5 and 35 at.%, RCCAs can contain three or more principal elements and the element concentration can be greater than 35%. The 151 reported RHEAs/RCCAs are analyzed based on their composition, processing methods, microstructures, and phases. Mechanical properties, strengthening and deformation mechanisms, oxidation, and corrosion behavior, as well as tribology, of RHEA/RCCAs are summarized. Unique properties of some of these alloys make them promising candidates for high temperature applications beyond Ni-based superalloys and/or conventional refractory alloys. Methods of development and exploration, future directions of research and development, and potential applications of RHEAs are discussed.

Development and exploration of refractory high entropy alloys—A review

Surface modifications for the effective dispersion of carbon nanotubes in solvents and polymers

In situ preparation and continuous fiber spinning of poly(p-phenylene benzobisoxazole) composites with oligo-hydroxyamide-functionalized multi-walled carbon nanotubes

The design approach and validation of a single phase senary refractory high entropy alloy (HEA) MoNbTaTiVW was presented in the present study. The design approach was to combine phase diagram inspection of available binary and ternary systems and Calculation of Phase Diagrams prediction. Experiments using X-ray diffraction and scanning electron microscopy techniques verified a single phase microstructure in body centred cubic lattice for MoNbTaTiVW. The observed elemental segregation agrees well with the solidification prediction using the Scheil model. The lattice constant, density and microhardness were measured to be 0.3216 nm, 4.954 GPa and 11.70 g cm− 3 respectively. The atomic size difference, the Ω parameter, enthalpy of mixing and entropy of mixing for MoNbTaTiVW HEA are 3.1%, 11.1, − 3.4 kJ mol− 1 and +13.39 J K− 1 mol− 1 respectively.

Senary refractory high entropy alloy MoNbTaTiVW

This paper demonstrates that a senary refractory high-entropy alloy CrxMoNbTaVW can be tailored over a certain range of Cr content with the BCC structure for different microstructures and physical properties, assisted by CALPHAD simulations. Microstructure characterizations are performed using X-ray diffraction and scanning electron microscopy. Chemical micro-segregation during solidification predicted using the Scheil model generally agrees with the experimental results. The lattice constant, density, and Vickers' micro-hardness of the high-entropy alloy samples in the as-cast state are measured and discussed. For CrxMoNbTaVW, x=2.0 case appears exceeding the upper limit of maintaining a single BCC phase HEA, determined by the XRD patterns. The elemental dependence of the mixing thermodynamic properties (entropy, enthalpy and Gibbs energy) in BCC phase in the senary system is analyzed. The calculated entropy of mixing and enthalpy of mixing for CrMoNbTaVW are 14.7 J/K/mol and −662.5 J/mol respectively.

/pdf/senary-refractory-high-entropy-alloy-crxmonbtavw-rv4kte2idb.pdf

Senary refractory high-entropy alloy CrxMoNbTaVW

The electromagnetic shielding effectiveness of C–SiC/epoxy composites was investigated and compared with that of carbon fiber/epoxy composites. C–SiCs, short fibers with carbon cores and silicon carbide shells, were fabricated by a carbothermal reduction process using chopped carbon fibers (CFs) and rice husk ash. After presenting the morphology and structure of the C–SiC fibers, the electromagnetic interference shielding effect of SiC coated carbon short fibers is discussed. The Kα-band (26.5–40.0 GHz) shielding studies revealed that the maximum total shielding effectiveness (SET) of the composite with 25 vol% of C–SiCs is 17.07 dB, dominated by absorption, while the composite with 25 vol% of the same sized carbon fibers has a SET of 8.44 dB only.

Yi Zhang

Papers

In situ preparation and continuous fiber spinning of poly(p-phenylene benzobisoxazole) composites with oligo-hydroxyamide-functionalized multi-walled carbon nanotubes

Senary refractory high entropy alloy MoNbTaTiVW

Senary refractory high-entropy alloy CrxMoNbTaVW

Morphology and electromagnetic interference shielding effects of SiC coated carbon short fibers

Electromagnetic interference shielding effectiveness of high entropy AlCoCrFeNi alloy powder laden composites