Electromagnetic shielding and mechanical properties of thermally stable poly(ether ketone)/multi-walled carbon nanotube composites prepared using a twin-screw extruder equipped with novel fractional mixing elements

Abstract

In the current study, a twin screw extruder equipped with novel fractional mixing elements [FME] (for enhanced mixing) was used to prepare a thermally stable, mechanically strong and light weight electromagnetic interference (EMI) shielding material based on poly(ether ketone) [PEK]/multiwalled carbon nanotube [MWCNT] composites. SEM and TEM images showed a uniform dispersion of MWCNTs in the PEK/MWCNT composites even at a high loading of 6.4 vol%. This improved and efficient dispersion of nanotubes in the PEK matrix is reflected in the formation of an electrically conductive network at a very low percolation threshold value of 0.74 vol%. Achievement of an electromagnetic interference (EMI) shielding effectiveness (SE) value of −24 dB (>99% attenuation) at a loading of 6.4 vol% along with high thermal stability [i.e. degradation temperature at 10% mass loss (T_0.1) of 582 °C] and good mechanical properties (tensile strength-119 MPa and tensile modulus-6084 MPa) demonstrates its potential application as high performance EMI shields for demanding applications such as aerospace and defense where in addition to EMI shielding, mechanical strength and thermal stability are also important parameters.