Evaluation of the Mechanical and Electromagnetic Shielding Properties of Carbon Fiber Reinforced Thermoplastics Sheet Made of Unidirectional Tape

Carbon fiber reinforced thermoplastics (CFRTP) made of carbon fiber-polyamide 6 unidirectional (UD) tape with different layer-configuration and tape-length were fabricated using hot compression-molding, and then their mechanical and electromagnetic shielding properties were evaluated. The mechanical property was evaluated using a three-point bending test method. Whereas, electromagnetic interference shielding effectiveness (EMI-SE) was estimated using Simon formalism based on through-thickness electrical conductivity value. In addition, laminate analysis using a laser microscope was conducted to observe inter and intra-laminar of CFRTP. The results showed that maximum load and flexural modulus of CFRTP has a strong relationship with UD tape arrangement. Unidirectional layer configuration is the highest strength and modulus compared with others due to carbon fiber direction. Furthermore, UD tape length significantly influenced in increasing the modulus for randomly chopped CFRTP. While the total EMI-SE was 29-89 dB in the x-band frequency for all different layer-configuration and tape-length in which quasi-isotropic layer-configuration was the highest electromagnetic shielding performance. Dominant-absorption shielding mechanism was confirmed by higher absorption value rather than reflection, in the range of 21-74 dB from total EMI-SE value. The results revealed an opposite characteristic between mechanical and electromagnetic shielding properties related to UD tape configuration for laminated composite. Also, the intra-laminar analysis showed that electrical volume conductivity strongly influenced by fiber-to-fiber contact in the thickness direction of the composite. It confirmed that quasi-isotropic and bidirectional configuration have higher conductivity resulting in higher electromagnetic shielding performance compared with others.