Effects of conductive phase content on critical pressure of carbon black filled silicone rubber composite

In order to study quantitatively the piezoresistive characteristics of carbon black filled silicone rubber composite, which is the sensitive element of flexible force sensor, the composite samples with the mass ratio of carbon black to silicone rubber ranging from 0.10 to 0.14 were prepared and measured. Experimental results indicate that there exits a critical pressure which varies with the carbon black content. Based on the shell structure theory, the experimental phenomena are explained from the view that external pressure induces the formation and destruction of effective conductive paths, leading to the changes in the resistance of composite.