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Nanostructured composites built with microporous cellulose fibers and carbon nanotubes (CNTs) have potential impacts in the fields of energy storage, sensors, and flexible electronics. Few results have been shown for high mechanoelectrical sensitivity of CNT‐paper composite because of numerous current paths in the network. Here, CNT‐paper‐based nanostructured composite sensors whose sensitivities are generated by controlled tensile fracture of the composite are presented. Under uniaxial load, the cellulose fibers in the paper experience straightening, stiffening, and fracture. The cellulose fibers originally parallel to the tension are fractured while those inclined and perpendicular to the tension are reorganized to form crossbar junctions in the vicinity of a crack. The cross junctions exhibit resistive and capacitive sensitivity to the out‐of‐plane force by the compression of the junctions. Such piezoresistive and piezocapacitive sensitivities are characterized and evaluated for human behavior monitoring. [ABSTRACT FROM AUTHOR]

A kind of paper-based composite was prepared with short carbon fibers (CFs) and para-aramid fibrids through the process of papermaking. The dielectric properties of the paper-based composites at microwave frequency were investigated. Based on the Lichtenecker Rule, the dielectric constants of CFs in composites at different CF concentrations were calculated. The absorbing performances of paper-based composites were calculated from the test results of electromagnetic parameters. It was shown that for the composites loaded with 1 mm CFs, the real part of complex permittivity rises at first then tends to be stable with the increase of the CF content, and the imaginary part rises at first then falls slightly, while for composites loaded with 3 or 6 mm CFs, both the real and imaginary part of complex permittivity grows at first and then falls rapidly with the CF content increasing. When the CF content is below 10 wt%, the composites containing longer CFs have larger permittivity at the same concentration. The Lichtenecker Rule is found to be not suitable for the system studied in this paper, especially when the content of CFs is high. The variations of reflectance and absorbance with the content of CFs generally have analogous trends . It is also found that to achieve better absorbing performance, the length and content of CFs together with the thickness of composites should be considered. In this study, the lowest reflection loss at 10 GHz reaches –27.59 dB when the paper-based composite is loaded with 1 mm CFs at the concentration of 10 wt% and the optimum thickness of 1.84 mm. [ABSTRACT FROM AUTHOR]

The aim of this study was to improve the electrical resistivity, mechanical properties, and interfacial properties between the carbon fiber (CF) and cellulose of conductive paper containing 10% CF so as to better meet the demands for electric heating wood floors. With waterborne polyurethane (WPU) treatment and nitrogen plasma modification methods, the interfacial properties between CF and cellulose were improved dramatically. Fourier transform infrared spectrometry (FTIR) revealed that the plasma modification method reduced the C-H contents and introduced numerous polar groups onto the CF surface. Scanning electron microscopy (SEM) showed that the CF modified by WPU and plasma had good adhesion with cellulose. The tensile index, tensile energy absorption index, and burst index of the paper were enhanced because of the plasma and WPU coating. The carbon fiber and WPU method presented good synergistic action with respect to mechanical properties and electrical resistivity, and the lowest electrical resistivity of conductive paper was reduced from 0.68 Ω•cm² to 0.44 Ω•cm². [ABSTRACT FROM AUTHOR]

Short carbon fibers (SCF) were modified with oxidation and coupling treatment to improve their water-wettability and bonding properties. Four types of dispersants were studied and discussed. Short carbon fibers/plant fiber (PF) composite papers were prepared by papermaking techniques. Scanning electron microscopy (SEM) and tests to determine zeta potential, absorbance, tensile index, and conductivity were carried out to investigate the modified effect of SCF and the interfacial properties. Modification experimental results showed that the surface grooves were deepened and new superficial grooves were generated by the liquid acid oxidation. The reaction with the silane coupling agent provided higher density and more uniform distribution on the SCF surface than that of organic titanate, and it obviously increased the roughness and the absolute value of zeta potential. After modification, the hydrophilic properties and dispersion in aqueous solutions were improved, the SCFs could form a good mechanical grip with plant fibers, and the conductivity and physical strength of SCF/PF composite papers were enhanced. It was shown that there was obvious adhesive binding at the fiber overlap nodes by the SEM analysis. It was confirmed that the improvement of physical properties of composite paper can be ascribed to the interfacial enhancement. [ABSTRACT FROM AUTHOR]

Highlights: [•] We deposited multi-wall carbon nanotubes on carbon fiber paper with a simple CVD. [•] We investigated the inherent mechanism of Ni particle's self-dispersion. [•] The MWCNTs/CFP composite possesses wonderful electrical conductivity. [ABSTRACT FROM AUTHOR]

Summary: Despite the high energy density, the lithium metal electrode has been plagued for decades with a dendrite growth problem that can result in a battery thermal runaway. Here, we introduce anisotropic spatially heterogeneous three dimensional (3D) current collectors that prevent lithium deposition on the insulating electrolyte-facing surface and accommodate lithium deposition inside the spacious voids. The anisotropic spatial heterogeneity was introduced by a line-of-sight deposition of a thin SiO2 layer onto a carbon-fiber paper. The deposited SiO2 was later converted into SiC by a magnesiothermic reaction. The SiO2 and SiC decorated 3D current collectors were confirmed dendrite-free by ex situ SEM observation after a deep lithium deposition of 28.8Ccm−2 at a high current density of 4mAcm−2. A high lithium cycling efficiency of 94% was achieved over deep deposition (14.4Ccm−2) and stripping cycles in a carbonate based organic electrolyte, demonstrating the superiority of the novel current collector for dendrite control and lithium cycling. This strategy opens new avenues to address the dendrite problem by rationally designed current collectors and for the creation of a high energy density electrode. [ABSTRACT FROM AUTHOR]

This paper describes the analysis of a fibre-on-fibre abrasion test, in which two adjacent lengths of fibre contact one another in a twisted geometry. Consideration is given to the various factors contributing to the mechanical actions occurring during the test. Results are presented of a preliminary study, using this fibre-on-fibre abrasion technique, of the progressive changes accompanying the oxidative stabilisation of polyacrylonitrile (PAN) fibres in a set of partially-oxidised commercial samples. The effects of abrasion on the fibres are also examined using scanning electron microscopy (8EM). The analysis predicts that applied tension and level of twist should play major roles in determining the severity of the test, and this is borne out by experiment. Considering the influence of the oxidative treatment on PAN fibres, it is concluded that the abrasion life generally decreases as stabilisation proceeds. The SEM results indicate a transition from plastic to brittle behaviour, which can be accounted for in terms of simple structural models of FAN and oxidised PAN fibres. [ABSTRACT FROM AUTHOR]