Strongly enhanced mechanical and electromagnetic shielding properties of short carbon fiber reinforced epoxy composites by a comprehensive “absorption-transfer” interface

The development of short carbon fiber-reinforced polymers (SCFRPs) with high comprehensive performance is a crucial key for modern applications. However, weak interfacial adhesion between short carbon fibers (SCFs) and the epoxy matrix (EP) significantly limits stress transfer and load-bearing efficiency, resulting in suboptimal mechanical performance. In this work, a synergistic interface structure (absorption-transfer interface) has been generated by combining a cut carbon nanotube (CCNTs) and self-polymerized dopamine (PDA) to efficiently absorb and transfer external loads as well as enhance electromagnetic waves loss. The incorporation of CCNTs-PDA into the silane-modified SCFs-EP (SCFs-Si-EP) results in remarkable enhancements in flexural strengths, which increase by 208 %, compared with those of SCFs-Si-EP. The dominant failure mechanism changes from fiber pull-out to delamination failure after introduction of the CCNTs-PDA interface. Moreover, the SCFs-Si-EP composites exhibit an EMI shielding effectiveness of 47.3 dB with incorporation of CCNTs and 2 wt% PDA (SCFs-CP-EP-2). This enhancement is attributed to the conductive networks and scattering centers provided by the CCNTs-PDA interface layer, which facilitates interfacial polarization and optimizes impedance matching, thereby leading to efficient electromagnetic wave attenuation. As a result, the SCFs-CP-EP-2 shows excellent mechanical properties and admirable electromagnetic shielding performance.