TY  - JOUR
A1  - Fang, Peng
A1  - Hollaender, Lars
A1  - Wirges, Werner
A1  - Gerhard, Reimund
T1  - Piezoelectric d(33) coefficients in foamed and layered polymer piezoelectrets from dynamic mechano-electrical experiments, electro-mechanical resonance spectroscopy and acoustic-transducer measurements
JF  - Measurement science and technology
N2  - Piezoelectrets are novel transducer materials which can be widely applied in sensors and actuators. Here, three techniques for determining piezoelectric d(33) coefficients of piezoelectrets are reviewed and compared. Two types of piezoelectrets, polyethylene-naphthalate (PEN) polymer-foam piezoelectrets and fluorinated ethylene-propylene (FEP) copolymer-layer piezoelectrets, have been prepared and measured by means of dynamic, resonance, and acoustical methods. The dynamic measurements show that the d(33) coefficient of PEN-foam samples clearly decreases with increasing stress, but 80% of the initial d(33) can be retained after 1800 cycles of a continuous dynamic measurement in a mechanical fatigue test. The resonance measurements demonstrate that both PEN-foam and FEP-layer samples exhibit clear electro-mechanical resonances. PEN-foam samples show elastic moduli in the range from 1 to 12 MPa and d(33) values up to 500 pC N-1, while FEP-layer samples show homogeneous elastic moduli of about 0.3 MPa and d(33) values of about 280 pC N-1. The acoustical measurements reveal that both PEN-foam and FEP-layer samples exhibit stable frequency responses in the range from 5.7 to 20 kHz. In addition, d(33) coefficients obtained with different experimental methods are in good agreement with each other, which confirms the reliability of all three techniques.
KW  - piezoelectret
KW  - ferroelectret
KW  - dielectric resonance spectroscopy
KW  - piezoelectric measurements
KW  - acoustic-transducer materials
KW  - polyethylene naphthalate (PEN)
KW  - fluorinated ethylene-propylene copolymer (FEP)
Y1  - 2012
U6  - https://doi.org/10.1088/0957-0233/23/3/035604
SN  - 0957-0233
VL  - 23
IS  - 3
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -