Piezoelectric properties of irradiation-crosslinked polypropylene ferroelectrets

The cellular irradiation-cross-linked polypropylene films treated by a hot-press process are corona charged to be piezoelectric. For the samples charged at room temperature, quasistatic piezoelectric d(33) coefficients up to 400 pC/N are obtained. The d(33) coefficients are slightly dependent on pressure in the range up to 50 kPa. The d(33) values decrease to 30% when the samples are exposed to 90 degrees C for 1 day; a preaging treatment improves the thermal stability of d(33). The dominant drift path of the detrapped charges is from one void surface to the adjacent void surface through the bulk of the solid. (C) 2007 American Institute of Physics.