| Abstract: | This report describes isothermal aging of piezoelectricity in poly(vinylidene fluoride) (PVDF) based on long-term heat treatments between 40 and 160°C. The results demonstrate that no piezoelectric decay occurs below about 60°C, that between 60 and 160°C the aging behavior follows logarithmic kinetics, and that aging is linearly dependent on temperature. Both uniaxial and biaxial PVDF show similar trends, but piezoelectric decay is more rapid for uniaxial film. Decay of permanent poling-induced polarization is identified as the likeliest cause of piezoelectric aging, and piezoelectric decay is found to be associated with long-range annealing effects which also produce macroscopic shrinkage of the PVDF film. |
