Role of Cnt Film Configuration in the Flexural Performance of Hybrid Composite with Cf

Abstract

The role of carbon nanotube film (CNTF) in improving the flexural performance of carbon fiber-reinforced polymer (CFRP) composites was investigated to address the demand for lightweight structural materials with enhanced mechanical properties. CNT films were employed to overcome the limitations of short-length CNTs in powder form, including poor dispersion, random alignment, and low producibility. The films were interleaved between carbon fiber prepreg layers in different thicknesses (1-ply, 2-ply, and 3-ply) and configurations, including surface-facing (SF) designs with parallel and orthogonal orientation. Flexural behavior and viscoelastic characteristics were evaluated using three-point bending and dynamic mechanical analysis (DMA). All CNT-interleaved hybrid composites exhibited improved flexural properties relative to baseline CFRP. The 2-ply hybrid composite exhibited a 44% increase in flexural strength over the CFRP, attributed to enhanced shear resistance and stress redistribution at the neutral axis. A tenfold increase in storage modulus indicated that the CNT network structure mechanically restricted bundle slippage, thereby contributing to enhanced stiffness. In contrast, the 3-ply composite exhibited reduced flexural strength due to incomplete resin infiltration, which limited interfacial sliding and microstructural reorganization. Notably, the SF-parallel configuration, with CNT films positioned not only at the center but also at both outermost layers, achieved the highest flexural strength (~1.8×) without significant changes in shear-related moduli, suggesting effective reinforcement of compressive and tensile regions. These findings highlight the structural role of CNT films in modulating flexural response.

Keywords: CNT film, hybrid composite, flexural strength, Storage modulus, loss modulus