Copper nanowire/polystyrene nanocomposites: Lower percolation threshold and higher EMI shielding

A highly conductive with exceptional electromagnetic interference (EMI) shielding capabilities copper nanowire (CuNW)/Polystyrene (PS) composite powder was formulated by solution processing. We used a dilution process where the conductive powder was then dry mixed with pure PS powder to prepare composites with lower CuNW concentration. The composite parts were prepared by compression molding. The electrical percolation threshold of the composite prepared by the dilution process followed by the compression molding was only 0.24 vol.% CuNW. Electron micrographs indicated that the conductive powder formed a segregated network within the polymer matrix. The EMI shielding effectiveness (SE) results showed that in the X-band frequency range, a 210 μm film made of PS composite containing 1.3 vol.% CuNW has an EMI SE of 27 dB and PS with 2.1 vol.% CuNW has an EMI SE of 35 dB. For 1.3 vol.% and 2.1 vol.% CuNW composites, contribution of absorption to the overall shielding was ∼54% of the overall EMI SE.