The method of matching resonance frequencies in coupled transmitter PVDF/TRFE diaphragms

The influence of thermal aging on the resonance frequency and electric impedance of polyvinylidenefluoride (PVDF) type polymer films was studied with the aim to apply thermal treatment to modify and tune the parameters of polymer electromechanical transducers. Results of our study show that thermal treatment of PVDF/TRFE 75/25 copolymer in the temperature range 50 to 125/spl deg/C (10 min) can be applied for matching the resonance frequencies of coupled transducers. The resonance frequency of the copolymer was found to increase linearly with the rise of the annealing temperature by /spl sim/12%, whereas the related decrease in the electromechanical coupling coefficient does not exceed /spl sim/11%.