Erosion Study of Poly(ethylene tetrafluoroethylene) (Tefzel) by Hyperthermal Atomic Oxygen

Everett, Michael L.; Hoflund, Gar B.

doi:10.1021/ma049515r

Cited by 20 publications

(21 citation statements)

References 24 publications

(39 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The two commonly used techniques for simulating the atomic oxygen found in LEO are: a) hyperthermal or fast atomic oxygen [69][70][71], and b) oxygen plasma [11,55]. In this study the oxygen plasma method, provided by the facility at NASA Glenn, was utilized using an electron cyclotron resonance (ECR) plasma source to produce neutral atomic oxygen.…”

Section: Atomic Oxygen and Vacuum Uv Radiation Effectsmentioning

confidence: 99%

Characterization, performance and optimization of PVDF as a piezoelectric film for advanced space mirror concepts.

Jones¹,

Assink²,

Dargaville³

et al. 2005

View full text Add to dashboard Cite

Piezoelectric polymers based on polyvinylidene fluoride (PVDF) are of interest for large aperture spacebased telescopes as adaptive or smart materials. Dimensional adjustments of adaptive polymer films depend on controlled charge deposition. Predicting their long-term performance requires a detailed understanding of the piezoelectric material features, expected to suffer due to space environmental degradation. Hence, the degradation and performance of PVDF and its copolymers under various stress environments expected in low Earth orbit has been reviewed and investigated. Various experiments were conducted to expose these polymers to elevated temperature, vacuum UV, γ-radiation and atomic oxygen. The resulting degradative processes were evaluated. The overall materials performance is governed by a combination of chemical and physical degradation processes. Molecular changes are primarily induced via radiative damage, and physical damage from temperature and atomic oxygen exposure is evident as depoling, loss of orientation and surface erosion. The effects of combined vacuum UV radiation and atomic oxygen resulted in expected surface erosion and pitting rates that determine the lifetime of thin films. Interestingly, the piezo responsiveness in the underlying bulk material remained largely unchanged. This study has delivered a comprehensive framework for material properties and degradation sensitivities with variations in individual polymer performances clearly apparent. The results provide guidance for material selection, qualification, optimization strategies, feedback for manufacturing and processing, or alternative materials. Further material qualification should be conducted via experiments under actual space conditions. 3 4 AcknowledgementsThe authors express their appreciation to Bruce Tuttle for use of equipment to measure the d 33 coefficients, Jonathan Campbell for use of the evaporation chamber, Mark Stavig for DMA measurements, Gary Zender for acquiring the SEM images, Ralph

show abstract

Section: Atomic Oxygen and Vacuum Uv Radiation Effectsmentioning

confidence: 99%

Characterization, performance and optimization of PVDF as a piezoelectric film for advanced space mirror concepts.

Jones¹,

Assink²,

Dargaville³

et al. 2005

View full text Add to dashboard Cite

show abstract

“…The inhomogeneous distribution of functional grafted sites in the PEMs takes responsibility for the poor‐quality conductance at the low GDs (≤20%), while the surface fractures take place at the higher GDs 42,43 . To our knowledge, there have been very limited attentions on the chemical compositions and their distribution at the surface layers of graft‐type PEMs, 11–13,15,16,19–21,41,44–46 although such a topic is one of the primary steps toward an understanding of its degradation behavior 19–21,33,41–43,46 . In addition, all previous studies on the chemical compositions and distributions on the surface of graft‐type PEMs have been limited to GDs ≤ 50% (IECs ≤ 2.2 mmol/g) 11,12,15,16,19–21,44 .…”

Section: Introductionmentioning

confidence: 99%

Morphological characterization of grafted polymer electrolyte membranes at a surface layer for fuel cell application

Hao

Tap

Hieu

et al. 2021

J of Applied Polymer Sci

View full text Add to dashboard Cite

The morphology and elemental compositions at the surface of poly(styrene sulfonic acid) (PSSA) grafted poly(ethylene‐co‐tetrafluoroethylene) polymer electrolyte membranes (ETFE‐PEMs) in a grafting degree (GD) range of 0%–127% are investigated by using FE‐SEM and XPS analyses. The concentrations of elemental components at the surface are not a linear function of GDs, resulting from different grafting speeds at the surface and bulk. In addition, low accumulation of PSSA grafts on the surface of ETFE‐PEMs in the low GDs of 0%–19%, as well as their homogeneous distribution through the membranes at least at a GD of 19% are observed. At higher GDs of 19%–127%, the PSSA accumulation on the surface is relatively limited, indicating the presence of more PSSA grafts inside the bulk than on the surface. The surface signatures of ETFE‐PEMs over the entire GD range can be determined based on the grafting process. These interesting observations suggest the significant advantages of interfacial properties of ETFE‐PEMs for fuel cell applications.

show abstract

“…The amount of O 2 that chemisorbs provides a measure of the concentration of reactive sites in the near‐surface region. Previous studies have shown that AO‐exposed Kapton,11 Tedlar,43 and Tefzel44 chemisorb very large amounts of molecular oxygen, and this indicates that these surfaces contain a high concentration of reactive sites. These reactive sites are probably present because cross bonding cannot occur on account of geometrical constraints.…”

Section: Resultsmentioning

confidence: 94%

Chemical alteration of poly(tetrafluoroethylene) Teflon induced by exposure to vacuum ultraviolet radiation and comparison with exposure to hyperthermal atomic oxygen

Everett

Hoflund

2004

J. Polym. Sci. A Polym. Chem.

Self Cite

View full text Add to dashboard Cite

The chemical alteration of poly(tetrafluoroethylene) Teflon by vacuum ultraviolet radiation (VUV) (115-400 nm) has been examined with X-ray photoelectron spectroscopy (XPS). The initial F/C atom ratio of 1.98 decreases to 1.65 after a 2-h exposure. The F/C atom ratio is further reduced to a steady-state value of 1.60 after a 74-h exposure. The high-resolution XPS C1s data indicate that new chemical states of carbon form as F is removed and that the relative amounts of these states depend on the F content of the near-surface region. The states are most likely due to C bonded only to one F atom, C bonded only to other C atoms, and C that has lost a pair of electrons through the emission of F Ϫ . The exposure of the VUV-damaged surface to researchgrade O 2 results in the chemisorption of a very small amount of O, and this indicates that large quantities of reactive sites are not formed during the chemical erosion by VUV. Further exposure to VUV removes this chemisorbed oxygen. A comparison of the XPS data indicates that the mechanisms of chemical alteration by VUV radiation and hyperthermal (ϳ5 eV) atomic oxygen are different, as expected, because the excitation sources are quite different.

show abstract

Erosion Study of Poly(ethylene tetrafluoroethylene) (Tefzel) by Hyperthermal Atomic Oxygen

Cited by 20 publications

References 24 publications

Characterization, performance and optimization of PVDF as a piezoelectric film for advanced space mirror concepts.

Characterization, performance and optimization of PVDF as a piezoelectric film for advanced space mirror concepts.

Morphological characterization of grafted polymer electrolyte membranes at a surface layer for fuel cell application

Chemical alteration of poly(tetrafluoroethylene) Teflon induced by exposure to vacuum ultraviolet radiation and comparison with exposure to hyperthermal atomic oxygen

Contact Info

Product

Resources

About