The preparation of PPy/PPTA conductive composite films by electrochemical method is presented.The first step is to cast a thin layer of poly (p-phenylene-terephthalamide) (PPTA) on a slice of Pt working electrode. The second step is to electrochemically polymerize pyrrole on the PPTA/Pt working electrode. Both of the electrical conductivity and the mechanical properties of the PPy/PPTA composite film are better than those of the pure PPy film, and the film has excellent flexibility at low temperature, even in liquid nitrogen.The SEM picture of the cross-section of PPy,/PPTA composite film showed that the two components were well mixed.Cyclic voltammograms of PPy,/PPTA film in aqueous solution showed that the conductive films could be reduced and reoxidized. 相似文献
Graphene oxide (GO) was functionalized using three different diamines, namely ethylenediamine (EDA), 4,4′-diaminodiphenyl sulfone (DDS) and p-phenylenediamine (PPD) to reinforce an epoxy adhesive, with the aim of improving the bonding strength of carbon fiber/epoxy composite. The chemical structure of the functionalized GO (FGO) nanosheets was characterized by elemental analysis, FT-IR and XRD. Hand lay-up, as a simple method, was applied for 3-ply composite fabrication. In the sample preparation, the fiber-to-resin ratio of 40:60 (w:w) and fiber orientations of 0°, 90°, and 0° were used. The GO and FGO nanoparticles were first dispersed in the epoxy resin, and then the GO and FGO reinforced epoxy (GO- or FGO-epoxy) were directly introduced into the carbon fiber layers to improve the mechanical properties. The GO and FGO contents varied in the range of 0.1–0.5 wt%. Results showed that the mechanical properties, in terms of tensile and flexural properties, were mainly dependent on the type of GO functionalization followed by the percentage of modified GO. As a result, both the tensile and flexural strengths are effectively enhanced by the FGOs addition. The tensile and flexural moduli are also increased by the FGO filling in the epoxy resin due to the excellent elastic modulus of FGO. The optimal FGO content for effectively improving the overall composite mechanical performance was found to be 0.3 wt%. Scanning electron microscopy (SEM) revealed that the failure mechanism of carbon fibers pulled out from the epoxy matrix contributed to the enhancement of the mechanical performance of the epoxy. These results show that diamine FGOs can strengthen the interfacial bonding between the carbon fibers and the epoxy adhesive. 相似文献
Stretchable conductive fibers offer unparalleled advantages in the development of wearable strain sensors for smart textiles due to their excellent flexibility and weaveability.However,the practical applications of these fibers in wearable devices are hindered by either contradictory properties of conductive fibers(high stretchability versus high sensing stability),or lack of manufacturing scalability.Herein,we present a facile approach for highly stretchable self-crimping fiber strain sensors based on a polyether-ester(TPEE)elastomer matrix using a side-by-side bicomponent melt-spinning process involving two parallel but attached components with different shrinkage properties.The TPEE component serves as a highly elastic mechanical support layer within the bicomponent fibers,while the conductive component(E-TPEE)of carbon black(CB),multiwalled carbon nanotubes(MWCNTs)and TPEE works as a strain-sensitive layer.In addition to the intrinsic elasticity of the matrix,the TPEE/E-TPEE bicomponent fibers present an excellent form of elasticity due to self-crimping.The self-crimping elongation of the fibers can provide a large deformation,and after the crimp disappears,the intrinsic elastic deformation is responsible for monitoring the strain sensing.The reliable strain sensing range of the TPEE/E-TPEE composite fibers was 160%-270%and could be regulated by adjusting the crimp structure.More importantly,the TPEE/E-TPEE fibers had a diameter of 30-40 μm and tenacity of 40-50 MPa,showing the necessary practicality.This work introduces new possibilities for fiber strain sensors produced in standard industrial spinning machines. 相似文献
Nitrogen-doped graphene aerogels with three-dimensional network structures are fabricated using hydrothermal method which includes the reduction of graphene oxide by organic amine and self-assembly of reduced graphene oxide. The effect of amine-containing compounds including aniline, 2-aminoethanol, ethylenediamine, melamine and chitosan on the assembly of nitrogen-doped graphene aerogel is investigated. The microstructure and chemical composition of nitrogen-doped graphene aerogels are characterized. The results reveal that nitrogen-doped graphene aerogel prepared using aniline as nitrogen source possesses a large specific surface area, high nitrogen content, good mechanical strength and excellent electrical conductivity. Based on these features, the as-prepared nitrogen-doped graphene aerogel shows high performance in electrochemical detection of dopamine in the presence of uric acid and ascorbic acid. Given the facile and scalable processability of aerogels, the proposed nitrogen-doped graphene aerogels are expected to have potential applications in sensors and other related devices. 相似文献
To solve environmental problems caused by the spill of oil and other organic liquids, we have developed graphene/hollow carbon fiber composite aerogels (G-CF) with a low density, high hydrophobicity, buoyancy, and adsorption capacity up to 42.7 g g–1. 相似文献
Currently the preferred method for large-scale production of solution-processable graphene is via a nonconductive graphene oxide (GO) pathway, which uncontrollably cuts sheets into small pieces and/or introduces nanometer-sized holes in the basal plane. These structural changes significantly decrease some of graphene's remarkable electrical and mechanical properties. Here, we report an unprecedented fast and scalable approach to avoid these problems and directly produce large, highly conductive graphene sheets. This approach intentionally excludes KMnO(4) from Hummers' methods and exploits aromatic oxidation by nitronium ions combined with the unique properties of microwave heating. This combination promotes rapid and simultaneous oxidation of multiple non-neighboring carbon atoms across an entire graphene sheet, thereby producing only a minimum concentration of oxygen moieties sufficient to enable the separation of graphene sheets. Thus, separated graphene sheets, which are referred to as microwave-enabled low-oxygen graphene, are thermally stable and highly conductive without requiring further reduction. Even in the absence of polymeric or surfactant stabilizers, concentrated dispersions of graphene with clean and well-separated graphene sheets can be obtained in both aqueous and organic solvents. This rapid and scalable approach produces high-quality graphene sheets of low oxygen content, enabling a broad spectrum of applications via low-cost solution processing. 相似文献
The properties of polyvinyl alcohol (PVA) nanocomposite hydrogels influenced by nanoparticles are reviewed. Various kinds of nanoparticles with excellent mechanical and electrical properties have been introduced into PVA hydrogel to produce stretchable and conductive PVA nanocomposite hydrogel. Understanding the mechanism between the matrix of PVA hydrogel and nanoparticles is therefore critical for the development of PVA nanocomposite hydrogels. This review focuses on the nanoparticles include carbon nanotubes, graphene oxide and metal nanoparticles, and describes the effects of nanoparticles on the mechanical and conductive properties of PVA nanocomposite hydrogels. A new promising area of soft stretchable PVA nanocomposite hydrogel is highlighted for possible applications. Finally, a brief outlook for future research is presented. 相似文献
Three‐dimensional (3D) graphene‐based polymer/graphene aerogels with excellent mechanical properties are crucial for broad applications. The creation of such polymer/graphene aerogels remains challenging because of the poor dispersion and compatibility of polymer within the graphene matrix. By using the freezing‐directed assembly of graphene under the assistance of surfactant, 3D macroporous polystyrene/graphene aerogels (MPS‐GAs) with lightweight, superelastivity (80 % strain), high strength (80 kPa), and good electrical properties have been achieved in this study. The as‐prepared MPS‐GAs shows excellent electromechanical performance with stable cyclic resilient properties and sensitive resistance responses, thus making the MPS‐GAs promising candidates for applications in actuators, elastic conductors, strain/pressure sensors, and wearable devices. 相似文献
Multifunctional fibers have attracted widespread attention due to applications in flexible smart wearable devices. However, simultaneously obtaining a strong and functional woven fiber is still a great challenge owing to the conflict between the properties mentioned above. Herein, mechanically strong and highly conductive cellulose/carbon nanotube (CNT) composite fibers were spun using an aqueous alkaline/urea solution. The microstructure as well as physical properties of the resulting fibers were characterized via scanning electron microscopy, infrared spectroscopy, mechanical and electrical measurement. We demonstrated that carboxylic CNTs can be well dispersed in alkali/urea aqueous systems which also dissolved cellulose well. The subsequent wet spinning process aligned the CNTs and cellulose molecules inside the regenerated composite fiber well, enhancing the interaction between these two components and endowing the composite fiber having a 20% CNT loading with an excellent mechanical strength of 185 MPa. Benefiting from the formation of conductive paths, the composite fiber with the diameter of about 50 μm possessed an electrical conductivity value in the range of 64–1274 S/m for 5–20 wt% CNT loading. This excellent mechanical strength and high electrical conductivity enable the composite fiber to exhibit a great potential in joule heating; the heating temperature of cellulose/CNT-20 fiber reached more than 55 °C within 15 s at 9 V. In addition, the multifunctional filaments are further manufactured as a water sensor to measure humidity. This work provides a potential material that can be applied in the fields of wearable electronics and smart flexible fabrics.
In situ monitoring of resin flow, impregnation of carbon fiber fabrics, and curing during composite manufacturing are very important for determining the quality of composite parts. In conventional methods, sensors, such as optical fibers and strain gages, are bonded to or embedded in the composites for measuring the changes in mechanical and chemical properties. Although they can detect resin curing behavior and impregnation of carbon fibers, they may adversely affect the manufacturing process or structural integrity of the composites. In this study, carbon fiber itself was used as a sensor that minimizes the degradation of mechanical properties and increases the efficiency of monitoring the manufacturing process. The change in the electrical resistance of carbon fiber fabrics was monitored during the various manufacturing processes when the resin flowed through the carbon fiber fabric and curing progressed. The effectiveness of this monitoring method was confirmed, and it is expected to be applicable in monitoring the quality of the finished composite parts. 相似文献
The formation and physical properties of epoxy nanocomposites with carbon (nanotubes, graphene, and graphite), metal-containing, and aluminosilicate (montmorillonite and halloysite) fillers are considered. The mutual effect of both a matrix and nanoparticles on the composite structure is discussed. The role of the interfacial layer in the mechanical properties of nanocomposites is revealed. It is found that the concentration dependence of electrical and thermal conductivities of the composites is related to the percolation phenomenon. 相似文献