Investigation of the correlation between electrical conductivity and elongation at break in polyurethane-based adhesives

Electrical conductivity and elongation at break of polyurethane (PU) filled with two different grades of graphite, Ag-coated basalt particles and fibres were investigated in this paper. Percolation concentrations were determined to be as follows: 21 or 22 vol.% for PU/graphite composites, 29 vol.% for both PU/Ag-coated particles and PU/Ag-coated fibres composites. It was found that the steepest increase in electrical conductivity and the more pronounced decrease in elongation at break occurs at the same filler concentration range for all investigated systems. A good correlation between phenomenological model, introduced in [J. Mater. Sci. Lett. 18 (1999) 1457], and experimental data for all investigated systems was also observed.