Electrical and mechanical properties of electrically conductive polyether sulfone composites

Electrically conductive polyether sulfone (PES) composites containing carbon fibers, nickel fibers, stainless steel fibers or aluminum flakes at various volume fractions were fabricated and tested. For electromagnetic interference (EMI) shielding effectiveness > 50 dB, the minimum filler volume fraction was 40% for carbon fibers of length 200 or 400 μm, 20% for nickel fibers or stainless steel fibers, and 30% for aluminum flakes. The tensile strength first increased and then decreased with increasing filler content, such that the highest tensile strength occurred at 30 vol.% for carbon fibers as the filler, 10 vol.% for nickel or stainless steel fibers, and 20 vol.% for aluminum flakes. The best overall performance was provided by aluminum flakes at 30 vol.%; the resistivity was 7 × 10^-4 Ω.cm, the EMI shielding effectiveness was > 50 dB and the tensile strength was 62 MPa.