Selection and Optimization of Piezoelectric Polyvinylidene Fluoride Polymers for Adaptive Optics in Space Environments

Abstract

Various piezoelectric polymers based on polyvinylidene fluoride (PVDF) are of interest for large aperture space-based telescopes. Dimensional adjustments of adaptive polymer films depend on charge deposition and require a detailed understanding of the piezoelectric material responses which are expected to deteriorate owing to strong vacuum UV, γ -, X-ray, energetic particles and atomic oxygen exposure. We have investigated the degradation of PVDF and its copolymers under various stress environments detrimental to reliable operation in space. Initial radiation aging studies have shown complex material changes with lowered Curie temperatures, complex material changes with lowered melting points, morphological transformations and significant crosslinking, but little influence on piezoelectric d33 constants. Complex aging processes have also been observed in accelerated temperature environments inducing annealing phenomena and cyclic stresses. The results suggest that poling and chain orientation are negatively affected by radiation and temperature exposure. A framework for dealing with these complex material qualification issues and overall system survivability predictions in low earth orbit conditions has been established. It allows for improved material selection, feedback for manufacturing and processing, material optimization/stabilization strategies and provides guidance on any alternative materials.

Evaluation of piezoelectric PVDF polymers for use in space environments. III. Comparison of the effects of vacuum UV and gamma radiation

“…To reach such a high gel content the radiation must penetrate and cause crosslinking throughout the bulk of the film. The equivalent dose of γ‐radiation required for 80–90% gel formation is over 800 kGy, which confirms previous estimates that the dose from VUV‐radiation in LEO is in the order of MGys 7. The solvent swelling factors of the P(VDF‐TrFE) crosslinked network were also similar for the VUV samples (uptake = 14–23) compared with the γ‐irradiated samples at similar gel content (821 kGy, uptake = 7).…”

“…We described previously the issues of materials selection7, 8 and the systematic study of the effects of temperature9 and AO/vacuum UV‐radiation10 on piezoelectric vinylidene fluoride‐based polymers being evaluated for use in novel thin‐film adaptive optics 11. Two promising piezoelectric polymers, PVDF and P(VDF‐TrFE), were chosen from a range of potential candidate materials and it was shown that the reorientation of the dipoles due to thermal contraction and dipole randomization had a large contribution to depoling and hence the loss of piezoelectric properties.…”

Thermal analysis for study of the gamma radiation effects in poly(vinylidene fluoride)

“…When in the non-polar α-phase, it is considered as a high-performance polymer with high resistance to mechanical straining. It is also biocompatible, used in cardiac sutures and studied in orthopedic prosthesis (Laroche et al, 1995;Celina et al, 2005). PVDF is one of the most radiation-resistant polymers in the market, maintaining most of its mechanical properties after irradiation in the MGy range.…”

“…PVDF is one of the most radiation-resistant polymers in the market, maintaining most of its mechanical properties after irradiation in the MGy range. This feature is linked to its extensive use in the aerospace industry and the need for radiation sterilization for medical use (Celina et al, 2005;Seal et al, 2001). Gamma sterilization is becoming popular in the medical device and packaging industry because of convenience and low cost.…”

Nanoindentation, nanoscratch, and nanotensile testing of poly(vinylidene fluoride)‐polyhedral oligomeric silsesquioxane nanocomposites

“…Because PVDF is not as hard as some other piezoelectric materials, such as lead zirconate titanate (PZT), PbTiO 3 , and so on, it can easily be prepared to the soft and thin transducers which are dictated by the shape of the structures they coat. This property is very useful in fields of energy harvesting4, 5 and adaptive inflatable structures in aerospace engineering 6, 7. But unfortunately, neat PVDF cannot completely meet the mechanical, thermal, and oxidation resistance property requirements of some harsh environments 7–9.…”