Effect of uniaxial pressure on conduction behavior of carbon black filled poly(methyl vinyl siloxane) composites

The piezoresistive behavior of carbon black (CB) filled poly(methyl vinyl siloxane) (PMVS) vulcanites under uniaxial compression was studied.At filler weight frac- tions φ slightly above the percolation threshold φc,resistance first increased with pressure and then turned to decrease at a critical compressive stress,exhibiting a positive pressure co- efficient of resistance (PPCR) and a negative pressure coeffi- cient of resistance (NPCR) effects ,respectively.The NPCR effect became much more pronounced at φ>>φc,while com- pressive cycles facilitated the occurrence of the weak PPCR effect during compression.The PPCR-NPCR transition was a process related to true stress.It is believed that the changes of microstructure in the percolating network,i.e. the breakdown and the reformation of infinite conducting clusters,under pressure would be responsible for the uniaxial piezoresis- tance and the plastic deformation of the filled vulcanites.

The piezoresistive behavior of carbon black (CB) EiHed poly (methyl vinylsiloxane) (PMVS) vulcanites under uniaxial compression was stodied. At filler weight fractions phislightly above the percolation threshold phi_c resis-taace first increased with pressure and thenturned to decrease at a critical compressive stress, exhibiting a positive pressure coefficient ofresistance (PPCR) and a negative pressure coefficient of resistance (NPCK) effects, respectively.The NPCR effect became much more pronounced at phi >>phi_c while compressive cycles facilitated theoccurrence of the weak PPCE effect daring compression. The PPCR-NPCR transition was a processrelated to true stress. It is believed that the changes of microstructure in the percolatingnetwork, i.e. the breakdown and the reformation of infinite conducting clusters, under pressurewould be responsible for the iittiaxial piezoresistance and the plastic deformation of the filledvulcanites.