Thermally Stable Electromagnetic Interference Shielding Material From Polysulfone Nanocomposites: Comparison on Carbon Nanotube and Nanofiber Reinforcement

The present investigation aims to develop thermally stable electromagnetic interference shielding materials from polysulfone (PSU) nanocomposites filled with multiwall carbon nanotubes (MWCNT) or carbon nanofibers (CNF). The effect of filler type and their structural features such as aspect ratio (length/diameter) and wall integrity on the different properties of nanocomposites has been investigated. Nanocomposite filled with MWCNT/CNF exhibits higher thermal stability compared with the neat PSU matrix. The onset degradation temperature of PSU at 532 degrees C enhances to 537 and 538 degrees C at 3 wt% MWCNT and 3 wt% CNF loading, respectively. CNFs filled nanocomposite shows higher electromagnetic interference shielding effectiveness (EMISE) compared with MWCNT filled one at the same filler loading. Compared with MWCNT, CNF imparts lower electrical percolation threshold. Nanocomposite filled with MWCNTs possesses percolation threshold at 1.5 wt%, whereas nanocomposite filled with CNFs possesses the same at 0.9 wt%. The EMISE of 20-45 dB are obtained from only 1 mm thick CNF filled nanocomposites from the filler loading 3 to 10 wt%. This value of EMISE above 40 dB suggests that the prepared nanocomposite can be used as an effective lightweight EMI shielding material for high frequency (8.2-12.4 GHz) applications, where high thermal stability is required. POLYM. COMPOS. 36:566-575, 2015. (c) 2014 Society of Plastics Engineers