Performance research on CFRP composites improved by PVDF-carbon fiber integrated structure by imitating vine root-wall morphology

To address interlaminar bonding strength deficiencies and interfacial failure in carbon fiber reinforced polymer (CFRP) composites, this study aimed to improve the flexural properties of CFRP via electrospinning polyvinylidene fluoride (PVDF) fibers modified with polyethylene-co-maleic anhydride (PEMA) onto carbon fiber fabric by imitating vine root-wall morphology. Testing results showed that the prepared PVDF fibers had diameters ranging from several hundred nanometers to a few micrometers. These fibers displayed a randomly oriented morphology and formed a semi-bonded, integrated PVDF–carbon fiber structure. At a PVDF areal density of 0.12 g/m², the composite exhibited a 25.3% increase in flexural strength and a 31% improvement in energy absorption compared to the unreinforced sample. The PVDF fibers featured stable backbones with freely movable ends, which promoted the formation of a fiber bridging architecture. This structure optimized the resin-rich regions (RRR) and the interfacial transition region (ITR), and could even penetrate adjacent carbon fiber layers. Thus, a three-dimensional interlocking structure was created, which effectively suppressed the initiation and propagation of microcracks. The failure mode shifted from delamination-dominated failure to quasi-shear failure.