Continuous kneading of composite conductive plastics with stainless steel fiber filling and its evaluation.

With ABS resin as matrix material and stainless steel fibers as conductive filler, the continuous kneading of composite conductive plastics was performed by changing operation conditions, such as the filling ratio of fillers, the feeding rate of raw materials, the revolution speed of paddles and the kneading temperature. The electric conductivity and shielding effectiveness of the material kneaded and the dispersion state of fillers were investigated.It was found that the composite conductive plastics being useful as an EMI shield material for electronic instruments were obtained with the filling ratio above 10 wt%, and the electric conductivity and shielding effectiveness could be improved by kneading under a proper operation condition, i.e. an optimum feeding rate, lower revolution speed and higher kneading temperature.Also, it was clarified that under such an operation condition the dispersion state of fillers in the matrix resin were dispersed effectively, forming a network of conductive paths and reducing breakage of fillers during kneading.