Electrical resistivity of hot-pressed silver-polystyrene powder mixture

Abstract

Electrical volume resistivity and bulk density during hot-pressing were measured simultaneously on silver-polystyrene equal-sized binary powder mixture under three different conditions: (1) at constant rate of temperature increase under constant pressure; (2) at constant temperature and pressure, and (3) at constant temperature and constant rate of pressure increase. Volume resistivity decreased with increasing pressure at all temperatures studied (50 to 164° C). Above the softening temperature of polystyrene (101° C) volume resistivity under the constant pressure increased with time even after the bulk density of the compact became constant. Judging from the scanning electron micrographs, contiguity of silver particles seems to be gradually hindered due to the penetration of thin films of polystyrene between silver particles after the onset of softening of polystyrene. A new method of preparing plastic-based composites with desired electrical resistivity is therefore possible through appropriate hot-pressing of metal-polymer powder mixture.