Enhanced Multifunctionality in Carbon Fiber/Carbon Nanotube Reinforced PEEK Hybrid Composites: Superior Combination of Mechanical Properties, Electrical Conductivity, and EMI Shielding

This study presents a novel approach to manufacturing carbon fiber and carbon nanotube-reinforced PEEK hybrid composites (CF/CNT/PEEK) using compression molding. The hybrid composite characteristics were compared with those of a control composite (CF/PEEK). Various tests were conducted on both composite types to investigate the impact of incorporating a carbon nanotube sock layer (an ultra-thin layer of a low-density CNT network), including three-point bend, electrical conductivity, and EMI shielding. The research also underscored the importance of EMI shielding simulation. An important aspect of the study involved performing multiscale simulations on control and hybrid composites, employing a digital twin methodology, and validating the results with experimental findings. For the hybrid composite, double multiscale simulations were performed by integrating two local-scale models, a CF/PEEK unit cell (micro-scale) and a CNT/PEEK representative volume element (RVE) (nano-scale), into a global-scale model. A detailed post-processing analysis of the simulation results was conducted to analyze stress distribution on local and global scale models. It was noted that there was an over 8% increase in the flexural strength of the hybrid composite, along with a reduction of over 27% in the standard deviation of the results. The introduction of CNTs enhanced the electrical conductivity by more than 36%. It conferred remarkable EMI shielding effectiveness exceeding 50 dB across the entire X-band frequency range, attributed to enhanced reflection and absorption. EMI shielding simulations suggest that refining the manufacturing process of the hybrid composite could enhance its shielding properties. The developed multiscale simulation has been demonstrated as an efficient prediction tool, as the simulation outcomes closely align with experimental findings. The resultant hybrid composite is promising for potential multifunctional applications.