Evaluation of piezoelectric poly(vinylidene fluoride) polymers for use in space environments. I. Temperature limitations

Smart materials, such as thin-film piezoelectric polymers, are interesting for potential applications on Gossamer spacecraft. This investigation aims to predict the performance and long-term stability of the piezoelectric properties of poly(vinylidene fluoride) (PVDF) and its copolymers under conditions simulating the low-Earth-orbit environment. To examine the effects of temperature on the piezoelectric properties of PVDF, poly(vinylidenefluoride-co-trifluoroethylene), and poly(vinylidenefluoride-co-hexafluoropropylene), the d(33) piezoelectric coefficients were measured up to 160 degrees C, and the electric displacement/electric field (D-E) hysteresis loops were measured from -80 to +110 degrees C. The room-temperature d(33) coefficient of PVDF homopolymer films, annealed at 50, 80, and 125 degrees C, dropped rapidly within a few days of thermal exposure and then remained unchanged. In contrast, the TrFE copolymer exhibited greater thermal stability than the homopolymer, with d(33) remaining almost unchanged up to 125 degrees C. The HFP copolymer exhibited poor retention of d(33) at temperatures above 80 degrees C. In situ D-E loop measurements from -80 to +110 degrees C showed that the remanent polarization of the TrFE copolymer was more stable than that of the PVDF homopolymer. D-E hysteresis loop and d(33) results were also compared with the deflection of the PVDF homopolymer and TrFE copolymer bimorphs tested over a wide temperature range. (c) 2005 Wiley Periodicals, Inc.