Changes to Tensile Strength and Electromagnetic Shielding Effectiveness in Neutron Irradiated Carbon Nanocomposites

Electromagnetic interference shielding effectiveness (EMI-SE) and tensile strength of nanocomposites containing multi-walled carbon nanotubes (MWNTs) are investigated following neutron irradiation. This nanocomposite material consists of two plies of MWNTs in an epoxy resin, and 4 plies of an E-glass substrate. EMI-SE measurements over the X-band frequency spectrum and monotonic tension tests to determine Young’s Modulus were performed before and after irradiation on the nanocomposite material. The nanocomposite and the MWNT plies were irradiated to a total fluence of 1.4 × 1014 1 MeV (Si-eq) n/cm2. The nanocomposites showed an average increase of 8 dB in shielding effectiveness after irradiation. However, the increase was not permanent with a return to pre-irradiation values after approximately 10 days at ambient temperature and pressure. The tensile strength and Young’s Modulus showed an 8% and 10% increase, respectively, following irradiation. This small increase is a result of the neutron induced embrittlement of the nanocomposite. Raman spectra of the MWNT plies showed a 150% increase in the D/G peak ratios after irradiation. This indicates damage in the plies due to neutron interactions in the MWNTs that does not lead to a commensurate reduction in EMI-SE or tensile strength in the nanocomposite material