Piezoresistance of conductor filled insulator composites

Several series of electrically conducting composites composed of a conducti ng filler randomly dispersed into an insulating polymer matrix were prepare d. The fillers were the tin-lead alloy powder, copper powder, aluminium pow der and ca;bon black, and the matrices were polyethylene, polystyrene and e poxy resin. The piezoresistance effects of these composites have been inves tigated under uniaxial presses. It was observed that the piezoresistance de pends on the applied stress, filler particle diameter, filler volume fracti on, matrix compressive modulus and potential barrier height. Piezoresistanc e increases with increase of applied stress, filler particle diameter and p otential barrier height, but decreases with increases of filler volume frac tion and matrix compressive modulus. A model based on the change in interpa rticle separation under applied stress, is developed. By analysing this mod el, the piezoresistance of composites is studied and the effects of influen cing factors are theoretically predicted quantitatively, showing good agree ment with the experimental data. (C) 2001 Society of Chemical Industry.