Effect of boron nitride nanoplatelet loading on the thermomechanical performance, thermal stability and X-band electromagnetic interference shielding of carbon-fiber/epoxy laminates

Woven carbon-fiber/epoxy laminates containing 0, 0.5, and 2 wt.% boron nitride nanoplatelets (BNNPs), relative to the epoxy resin mass, were fabricated using the same processing route. Their thermomechanical behavior, thermal stability, and X-band electromagnetic interference (EMI) shielding were evaluated using dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and shielding effectiveness (SE) measurements over 8–12 GHz. At 0.5 wt.% BNNP, the glassy storage modulus ( E ′) increased from 9.3 to 11.2 GPa, and the rubbery plateau modulus increased from 0.33 to 2.1 GPa. The loss factor (tan δ) peak temperature shifted from 95.84 to 105.23 °C, while the temperature at 5 % mass loss (Td5) increased from 305.95 to 314.04 °C. The residual mass at 900 °C increased from 68.53 % for the neat laminate to 72.38–72.93 % for the BNNP-containing laminates. The band-averaged total SE values were approximately 50, 46, and 43 dB for the laminates containing 0, 0.5, and 2 wt.% BNNP, respectively. Although the SE curves crossed at several frequencies, the band-averaged values decreased with increasing BNNP content. Among the formulations tested, the 0.5 wt.% BNNP laminate showed the most favorable thermomechanical response, with a reduction in band-averaged EMI shielding relative to the neat laminate.