Comparison of flexural properties of two different CFRPs before and after low-velocity impact: T1000 vs T300 interleaved with micro-/nano- Aramid fibers

T1000 carbon fibers are far superior to T300 fibers in tension, but the performance of bulk T1000 composites can be matched by bulk T300 composites interleaved with sparsely distributed micro-/nano- Aramid pulp (AP) fibers. In this study, we focus not only on the short-beam shear strength but also on the flexural strength of T1000 and T300-AP composites before and after impact, as these properties are critical indicators of structural performance under bending-dominated loading conditions. Maintaining the AP-epoxy interlayer thickness at 8 μm or less, with AP areal densities of 2, 4 and 6 gram/m 2 , leads to improvements of up to 38% in short-beam shear strength and 55% in flexural strength for the T300-AP composites, surpassing the performance of plain T1000 composites without such AP-interfacial toughening. These findings highlight the importance of interfacial design and quasi-Z-directional fiber bridging in CFRPs, demonstrating that resin-rich layers between carbon fiber plies as thin as 15 μm can be transformed into mechanically interlocked ply interfaces through AP-interfacial toughening, thereby bringing the structural performance of T300-AP composites to parity with that of T1000 composites.