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This article reports a novel hybrid multiscale carbon-fiber/epoxy composite reinforced with self-healing core-shell nanofibers at interfaces. The ultrathin self-healing fibers were fabricated by means of coelectrospinning, in which liquid dicyclopentadiene (DCPD) as the healing agent was enwrapped into polyacrylonitrile (PAN) to form core-shell DCPD/PAN nanofibers. These core-shell nanofibers were incorporated at interfaces of neighboring carbon-fiber fabrics prior to resin infusion and formed into ultrathin self-healing interlayers after resin infusion and curing. The core-shell DCPD/PAN fibers are expected to function to self-repair the interfacial damages in composite laminates, e.g., delamination. Wet layup, followed by vacuum-assisted resin transfer molding (VARTM) technique, was used to process the proof-of-concept hybrid multiscale self-healing composite. Three-point bending test was utilized to evaluate the self-healing effect of the core-shell nanofibers on the flexural stiffness of the composite laminate after predamage failure. Experimental results indicate that the flexural stiffness of such novel self-healing composite after predamage failure can be completely recovered by the self-healing nanofiber interlayers. Scanning electron microscope (SEM) was utilized for fractographical analysis of the failed samples. SEM micrographs clearly evidenced the release of healing agent at laminate interfaces and the toughening and self-healing mechanisms of the core-shell nanofibers. This study expects a family of novel high-strength, lightweight structural polymer composites with self-healing function for potential use in aerospace and aeronautical structures, sports utilities, etc. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the fabrication and mechanical properties of hybrid multi-scale epoxy composites reinforced with conventional carbon fiber (CF) fabrics surface-attached with electrospun carbon nanofiber (ECN) mats. The ECNs were prepared via thermal treatments of polyacrylonitrile copolymer nanofibers, which were produced by the electrospinning technique and collected as overlaid mats on the T300 CF fabrics. The ECN-CF fabrics/mats were used as innovative reinforcement fillers for the fabrication of hybrid multi-scale composites (with SC-15 epoxy resin) through the composite-manufacturing technique of vacuum assisted resin transfer molding. Three-point bending test and short-beam shear test were carried out to evaluate the strengthening/toughening effects of ECNs on mechanical properties of the novel composites. The results indicated that out-of-plane mechanical properties of the ECN-CF/epoxy composites were considerably higher than the control sample of traditional CF/epoxy composites. [Copyright &y& Elsevier]