The strain-sensing behaviors of carbon black/polypropylene and carbon nanotubes/polypropylene conductive composites prepared by the vacuum-assisted hot compression

The strain-sensing behaviors of carbon black (CB)/polypropylene (PP) and carbon nanotubes (CNTs)/PP conductive composites prepared by the vacuum-assisted hot compression were studied and compared. When ten extension-retraction cycles were applied, it was found for CB/PP, the value of the maximum responsivity (ΔR/R0, ΔR—the instantaneous variation of the resistance during the test, R0—the original resistance) decreased gradually with increasing the cycle number, but it began to rise from the seventh cycle. The value of the min ΔR/R0 increased during the whole test. While for CNTs/PP, both the values of the max and min ΔR/R0 decreased rapidly. It is suggested that the different behaviors mainly depend on the distinction in the dimension of the conductive fillers and the preparation technique.