Enhanced Thermoelectric Properties of WS2/Single-Walled Carbon Nanohorn Nanocomposites

Recently, two-dimensional tungsten disulfide (WS2) has attracted attention as a next generation thermoelectric material due to a favorable Seebeck coefficient. However, its thermoelectric efficiency still needs to be improved due to the intrinsically low electrical conductivity of WS2. In the present study, thermoelectric properties of WS2 hybridized with highly conductive single-walled carbon nanohorns (SWCNHs) were investigated. The WS2/SWCNH nanocomposites were fabricated by annealing the mixture of WS2 and SWCNHs using a high-frequency induction heated sintering (HFIHS) system. By adding SWCNHs to WS2, the nanocomposites exhibited increased electrical conductivity and a slightly decreased Seebeck coefficient with the content of SWCNHs. Hence, the maximum power factor of 128.41 μW/mK2 was achieved for WS2/SWCNHs with 0.1 wt.% SWCNHs at 780 K, resulting in a significantly improved thermoelectric figure of merit (zT) value of 0.027 compared to that of pristine WS2 with zT 0.017.

Percolative Composites with Carbon Nanohorns: Low-Frequency and Ultra-High Frequency Response

We systematically studied the electromagnetic properties of carbon nanohorns (CNHs) and polystyrene composites filled with CNHs in static regime, low frequency and microwave regions. CNHs were synthesized using the direct current arc-discharge method using solid graphite rods and graphite rods filled by melamine mixed with graphite powder. Transmission electron microscopy and thermo-gravimetric analysis showed that CNH agglomerates are the main product, while the addition of melamine promotes the formation of graphite balls. Graphitic contamination causes the internal leakage of inter-agglomerate capacity, lowering the permittivity and enhancing the conductivity of composites. The permittivity of CNH/polystyrene composites increases with the filler fraction, and near the dielectric threshold electromagnetic characteristics of the composites exhibit critical behaviour. Our results suggest that CNHs with relatively high values of permittivity and contact resistance could be used as high-k materials.

Formation of highly ordered micro fillers in polymeric matrix by electro-field-assisted aligning

Nanocomposites composed by polymeric matrix with micro/nano fillers have drawn lots of attention since their dramatic properties beyond pristine polymers. The spatial distribution of the micro/nano fillers in the polymeric matrix determines the final desired properties of the nanocomposites, thus deserves to investigate. Here, we proposed an effective method of assembling the micro/nano fillers to pre-designed patterns within the polymeric matrix by AC-electro-field-assisted aligning. By pre-designed AC electric fields which could be dynamically controllable, the distribution of microparticles (acting as fillers) in the matrix was tuned to various patterns related to the electric fields, such as linear alignment and circular alignment. The field-oriented particles chains could act as endoskeletal structures, showing unique properties (i.e., mechanical, optical, and anisotropic properties) beyond those of the conventional composites with randomly distributed particles.

Nanocomposites composed by polymeric matrix with micro/nano fillers have drawn lots of attention since their dramatic properties beyond pristine polymers.

Design and development of a poly(acrylonitrile-co-methyl methacrylate) copolymer to improve the viscoelastic and surface properties critical to scratch resistance

The present paper reports the design, development and evaluation of methyl methacrylate (MMA) and acrylonitrile (AN) copolymers to improve viscoelastic and surface properties critical to scratch resistance.