Materials/Polymers/Fluoropolymers

Clear Tedlar

misse2-pvf-clear-tedlar

In short

On the International Space Station's forward-facing side, oxygen atoms ate away 269 µm of Clear Tedlar in 3.95 years, about 68 µm a year. A standard 25 µm film of it would last about 4 months there. It erodes 1.1 times faster than Kapton H, the reference film.

Benchmarks

The benchmarks that matter for this material's applications, each compared with the reference engineers use.

BenchmarkResultCompared with reference
Atomic oxygen erosionHow fast low-orbit oxygen eats the surface. Lower is better. 3.19×10⁻²⁴ cm³/atomLow Earth orbit, 3.95 years in flight 1.06× Kapton HErodes 1.1× faster

Not measured yet (7): darkening under UV and particles (Δα); outgassing, total mass loss (TML); outgassing, condensable (CVCM); solar absorptance (α); thermal emittance (ε); thermal cycling survival; flammability (crewed vehicles).

Applications

Where materials like Clear Tedlar are considered, the benchmarks that decide each use, and what the measured data says so far.

ApplicationDeciding benchmarksWhat the data says
External surfaces in low Earth orbit1 of 2 deciding benchmarks measured
  • Atomic oxygen erosion
  • Darkening under UV and particles (Δα)
Atomic oxygen resistance is poor (1.06×): unprotected, it wears through quickly on forward-facing low-orbit surfaces and would need a protective coating. Still needed: darkening under UV and particles (Δα).
Thermal blankets (MLI) outer layer1 of 4 deciding benchmarks measured
  • Atomic oxygen erosion
  • Darkening under UV and particles (Δα)
  • Outgassing, total mass loss (TML)
  • Outgassing, condensable (CVCM)
Atomic oxygen resistance is poor (1.06×): unprotected, it wears through quickly on forward-facing low-orbit surfaces and would need a protective coating. Still needed: darkening under UV and particles (Δα); outgassing, total mass loss (TML); outgassing, condensable (CVCM).
Radiators and thermal coatings0 of 3 deciding benchmarks measured
  • Solar absorptance (α)
  • Thermal emittance (ε)
  • Darkening under UV and particles (Δα)
None of the deciding benchmarks are measured yet. Side check: atomic oxygen resistance is poor (1.06×).

"What the data says" is Space Mushroom's reading of the measured values, not a flight qualification. Deciding benchmarks come from the Benchmark Framework.

What it went through

WhereISS, MISSE 2, PEC 2 tray 1 (outside the Quest airlock)
When2001-08-16 to 2005-07-30 (3.95 years)
Atomic oxygen dose8.43×10²¹ atoms/cm²
Sunlight5,000–6,700 equivalent sun hours
TemperatureCycled between −30 °C and 40 °C
Also exposed toSolar UV and charged particle radiation, in vacuum

How it compares

Materials flown on the same tray, ranked from least to most eroded. Clear Tedlar is number 28 of 40.

RankMaterialCompared with Kapton HLost in 3.95 years
5 FEPFluorinated ethylene propylene 0.067× 17 µm
25 Kapton HPolyimide (PMDA) 1.00× 253 µm
26 MylarPolyethylene terephthalate 1.00× 254 µm
27 PMR-15High temperature polyimide resin >1.01× >255 µm
28 Clear TedlarPolyvinyl fluoride 1.06× 269 µm
29 PEIPolyetherimide >1.10× >279 µm
30 PA 6Polyamide 6 (nylon 6) 1.17× 296 µm

How the numbers are calculated

  • Erosion yield is NASA's measurement: volume of material removed per oxygen atom.
  • Thickness lost = erosion yield × oxygen dose = 3.19×10⁻²⁴ cm³/atom × 8.43×10²¹ atoms/cm² = 0.0269 cm = 269 µm.
  • Compared with Kapton H = erosion yield ÷ 3.00×10⁻²⁴ (Kapton H's value on the same flight).
  • Film life = 25 µm ÷ 68 µm per year, for the same exposure.