To achieve the admirable electrically conductivity without sacrificing the outstanding integrated performance of meta-aramid fibers is still a challenge. A novel method is developed for fabricating of electrically conductive poly (m-phenylene isophthalamide) (PMIA) fibers in this paper. Firstly, the metal silver nanoparticles are deposited on the surface of PMIA fibers by simply dipping the fibers into a mixed aqueous suspension of dimethylsulfoxide (DMSO) and nano silver sol. Then, the silver nanoparticles, depositing on the surface of the PMIA fibers, are functioned as the catalyst for the subsequent procedure of electroless nickel deposition together with the anchor for the coating layer. Followed by electroless nickel plating, homogeneous and dense nickel-coated PMIA fibers are obtained. And the properties and structures of nickel-coated PMIA fibers are investigated systematically, the electrical resistance of the nickel-coated PMIA fibers is measured using the multimeter. Without any post-treatment, the electrical resistance of the modified PMIA fibers can be as low as 5.5 Ω cm À1 . Meanwhile, outstanding mechanical performances of pure PMIA fibers are well maintained. This study also demonstrates the necessity of adding a small amount of DMAB as an auxiliary reducing agent. This approach may be equally applicable to fabricate conductive coatings on other polymer materials.

In this article, active groups were introduced to the surface of aramid fiber by building a Cu2+ bridge between the aramid fiber and polyethyleneimine (PEI) to improve adhesion in composites between the aramid fiber and the matrix such as epoxy resin. The changes in the structure and properties of the aramid fiber were verified with Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and the single-fiber pull-out test. The FTIR and XPS results show a significant change in the structure and morphology of the aramid fiber after modification. The results of the single-fiber pull-out test show that the interfacial shear strength (IFSS) of epoxy composites reinforced with PEI-grafted aramid fiber increases by 48.8% compared with the IFSS of epoxy composites reinforced with untreated fiber. Thus, the proposed method can improve the interfacial bonding of composites by creating a copper ion bridge between the aramid fiber and PEI.

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To achieve satisfactory electrical conductivity is still a challenge, without sacrificing the superior integrated performance of meta-aramid (PMIA) fibers. Here a novel, bioinspired two-step approach was reported to fabricate surface-nickeled PMIA fibers with admirable electrical conductivity. The formation of polydopamine-functionalized silver nanoparticle assemblies (DOPA@AgNAS) deposited on the surface of the PMIA fibers simply included the magnetic stirring of 3,4-dihydroxy-l-phenylalanine (DOPA) and silver ammonia in an aqueous solution at room temperature and dipping the PMIA fibers into the aqueous solution simultaneously. After, the DOPA@AgNAS functioned as the catalyst for the subsequent progress of the electroless nickel plating. The as-prepared nickel-coated PMIA fibers (DOPA@AgNAS-Ni-PMIA) possess outstanding electrically conductive properties and exhibit exceptional mechanical stability. More importantly, because of its high flexibility, DOPA@AgNAS-Ni-PMIA can be utilized in numerous fields.

The poor interfacial adhesion between the aramid fiber (AF) and the matrix limits the application of the final composites. In this study, a novel coating method was adopted to modify AF Through metallization/grafting reaction, the copolymer synthesized by the low-temperature poly-condensation of p-phenylenediamine (PPDA), 4,4′-diaminodiphenyl ether (ODA) and terephthaloyl dichloride (TPC), was added into the dimethyl sulfoxide/sodium hydride (DMSO/NaH) solution, and a nano AF solution was obtained. Then epoxy groups were introduced to the amide bond by grafting Epichlorohydrin (ECH). By further grafting on Poly (propylene glycol) bis (2-aminopropyl ether) (PEA), more functional groups were introduced, which could increase the polarity of the fiber and the interfacial adhesion of the composites. The results show that not only the interfacial shear strength (IFSS) and the flexural strength of the aramid-reinforced composites has a significant increase compared with the untreated fibers, but the modification still maintains the mechanical properties of the fiber, indicating that building nanoscale coating solution is a very effective method to achieve non-destructive modification to ehance its interfacial adhesion with epoxy resin.