Processing conditions for electromagnetic interference shielding effectiveness and mechanical properties of acrylonitrile‐butadiene‐styrene based composites

Abstract A conductive plastic was compounded in a twin screw extruder by incorporating conductive carbon fiber (CF) into an acrylonitrile‐butadience‐styrene (ABS) copolymer. The effects of various processing parameters prior to injection molding were investigated; then, the electromagnetic interference shielding effectiveness (EMI SE), fiber length, processability, and mechanical properties of the composite were studied. Results showed that the EMI SE of the composite increased as the final fiber length increased. The longer final fiber was produced by feeding fibers into the ABS melt at 240°C and 60 rpm. A more conductive network was formed by adding lubricants to the composite to reduce fiber damage and increase fiber dispersion. The increase of the fiber content affected processability. When the fiber content was higher than 40 phr (parts per hundred resin) in the composite, the average fiber length shortened. This study shows that better shielding can be obtained by adding a fiber at a rate higher than 30 phr. The best shielding obtained is about 30 decibels (dB).