Investigation on the piezoresistive behavior of high-density polyethylene/carbon black films in the elastic and plastic regimes

The piezoresistive behavior of two kinds of films, cast film and pressed film, based on high-density polyethylene/carbon-black composites is investigated for specimens loaded in axial tension. The tests are performed under a low number of cycles and different levels of applied strain. The normalized electrical resistance of the cast film is almost constant with strain in the elastic region and then it starts to increase with strain in the plastic region. However, for the pressed film, the normalized electrical resistance increases monotonically with strain. This unique behavior of resistance change of cast films can be applied to identify the elastic and plastic deformation in the composite. Moreover, two completely different strain sensing behaviors are presented in the cast film which undergo the cyclic tensile within the elastic regime and plastic regime. Finally, the normalized electrical resistance is simulated by using a mathematical model, taking into account the number of conductive paths and tunneling effect.