Manufacturability of Hybrid Aligned Carbon Nanotube (CNT)-Fiber Composites Through Vacuum Assisted Resin Infusion As Dependent On CNT Loading

Fiber reinforced plastics are increasingly employed in the aerospace industry to capitalize on their high specific strength and stiffness in response to demands for lighter high performance materials. Performance is often limited by interlaminar properties, which is often addressed through z-pinning and stitching with an accompanied drop in in-plane properties from the large diameter of reinforcements. Attempts to incorporate nanoscale fibers to reinforce the interlaminar region through matrix dispersion lead to prohibitively high processing viscosities, limiting the amount of nanofiller loading. In this work, the impact of the aligned carbon nanotube (CNT) loading on the manufacturability of fiber reinforced plastics is studied. Rather than incorporation through the matrix, the CNTs are arranged on advanced fiber weaves through in situ growth off the fibers surfaces (fuzzy fibers). The CNTs extend radially across interlaminar and intralaminar regions for mechanical reinforcement, but also drastically increase the laminate preform surface area. The influence of CNT length on the permeability of fuzzy fiber reinforced plastics (FFRP) is explored through a modified vacuum assisted resin infusion setup, and initial results revealed less than a 10x decrease in permeability of laminates with the longest CNTs, even though the surface area increased over 20x. Results indicate that infusion processing of large FFRP laminates with an unmodified aerospace-grade resin can be accomplished with standard vacuum assisted resin infusion setups. Production of laminates with controlled CNT morphology enables mechanical and multifunctional reinforcement with applications in interlaminar toughness reinforcement and non-destructive evaluation.