Electrical and mechanical property transitions in carbon-filled poly(vinylpyrrolidone)

The effect of carbon black content on the mechanical and electrical properties of carbon-black-filled poly(vinylpyrrolidone) composites was determined. Experimental data show a drop in modulus when the volume of carbon black exceeds 25%, coincident with pore formation documented by scanning electron microscopy. This behavior is consistent with surpassing the critical pigment volume concentration. Electrical conductivity, however, does not show a discontinuous change in behavior at 25 vol% carbon black and continues to increase through a carbon black loading of 35 vol%. A qualitative model of microstructural evolution is presented to explain the observed differences in electrical and mechanical behavior.