Hierarchical carbon nanotubes grown on 3D woven glass fiber preforms for multifunctional structural composites beams

Delamination and poor interfacial properties between matrix and reinforcement have been considered as major problems of laminated composites. They also limit their use in aerospace industry when durable, multifunctional and lightweight materials are of recent demand. In this study, mechanically robust and electrically conductive composite beams are manufactured by combining two innovative approaches such as 3D weaving and production of fuzzy fiber architecture of carbon nanotubes (CNTs) onto 3D preforms. 3D weaving enables the manufacturing of delamination-free preforms, while growing vertically aligned CNTs on fibers contributes to the electrical conductivity. Among several studies performed for enhancing the interlaminar properties of laminated composites, this novel approach eliminated the most probable failure as delamination in structural composites and allows to manufacture conductive complex 3D shapes without causing loss of tensile properties. Aligned CNTs (a-CNTs) were first grown by a modified chemical vapor deposition (m-CVD) method onto an I-profile shaped 3D glass fiber woven preforms. Those preforms were then impregnated with epoxy resin by vacuum infusion process (VIP) to form multifunctional 3D I-beam composites. The morphological analysis showed 7.57 μm long CNTs having radially aligned growth on glass fibers. The electrical conductivity of CNTs grown glass fibers measured by 4 point-probe set-up was 4.52×10^-2 S/cm, which was a remarkable enhancement of as over non-conductive glass fibers with an order of 10⁶ S/cm. Failure mechanisms subjected to flexural loading was also noted to explore the contribution of CNTs.