Constructing fiber bridging network of polyvinylidene fluoride at interlayer of carbon fiber reinforced polymer via electrospinning for improving flexural performance

To address the interfacial failure caused by insufficient interlaminar bonding in Carbon Fiber Reinforced Polymer (CFRP) composites, an effective electrospinning technique is proposed to prepare the Polyethylene-co-Maleic Anhydride (PEMA) modified Polyvinylidene Fluoride (PVDF) fibers on CF fabrics to improve the flexural performance. Testing results show that the prepared PVDF fibers had various diameters varying from several hundred nanometers to several micrometer and were disordered to form semi-bonded PVDF-CF integrated structure. CFRP composite with PVDF areal density of 0.16 g/m² yielded the greatest flexural strength of 888.24 MPa and post-impact residual flexural strength of 122.05 MPa, exhibiting 25.1% and 68.6% increments respectively. Fiber trunks of PVDF were relatively stable and fiber ends were free-moved, which made them easier to construct fiber bridging network in situ compared with the fiber agglomeration of directly introducing fiber. The PVDF fibers bridging network at the interlayer could improve brittle epoxy resin, embed interfacial transition region and even penetrate adjacent CF, forming a three-dimensional interlocking that suppressed micro-crack generation and propagation. This contributed to failure modes changing from delamination dominated failure of unreinforced CFRP composites to shear-dominated failure of PVDF-reinforced composites. Overall, electrospinning method could provide an important alternative for manufacturing high-performance laminated FRP composites in industrial field.